# My Garden Room Build - 9m x 4m



## Molynoox

I thought I would do a thread for my garden room build in case anybody is interested in the details.
I spent a huge amount of time researching everything and have learned a lot along the way and I figured that if this knowledge is useful to me then perhaps it could be useful to other's.
I have gained some good insights from people on this forum so hope I can contribute something back to the community.
I am over halfway through the build now, but will take it from the start so you can see every stage.

Although the primary goal is to share the knowledge with others in the same boat, I am also looking to receive your constructive feedback so that I can learn from my mistakes. So please feel free to comment, even if it is a criticism.

I will start with the plan:

9m x 4m external dimensions
30 m2 internal area (to keep it exempt from building regs, although it isn't that simple)
under 2.5m height (to keep it within permitted development and not need planning permission, although it isn't that simple)
wooden frame (5 x 2), PIR insulation (100mm all round), cement board sheething on 3 of the external sides
vented cold roof
alu doors and windows
metal header (flitch beam) above bi-fold, timber header above french door
EPDM roof
battens and cedar cladding
vapour bariers inside and out
bathroom (water and waste)
power and internet
groundscrew foundations
heat pump air con for heating and cooling
composite deck
cedar pergola (partly for shade, partly a privacy thing, for both us and the neighbours)

its all fairly predictable stuff I'm afraid :-D

I will attach some pics of the plan and then in the next post I will start with the first stage of the build.

Martin


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## Jameshow

Looks simalar to Dr Bob classy recent build! 

Cheers James


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## Molynoox

sounds interesting, I don't think I spotted that one - how recent? just so I can go and find it


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## Fitzroy

Looking forwards to it. ‘Although it isn’t that simple’ was a key learning when I built mine.


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## Jameshow

Bobby's home office / gym build


I have gone the permitted development route, I have a big garden and can keep it 2m from the boundry, the building is 3m high, so it seemed the easy sensible route. PD has been granted. I won't post up plans just daily progress pictures, I'm a few weeks into it so there is a delay in posting but...




www.ukworkshop.co.uk





Cheers James


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## Molynoox

thanks James, that build looks great. Very similar in looks to mine, but concrete base and SIPS makes it quite a different beast to mine. Very interesting thanks for pointing it out.


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## Molynoox

*Feb 2021 - Planning*

Before going any further (back in February) we considered a few key planning aspects:

Placement and size of garden room
Impact on neighbours / privacy concerns
Planning permission / permitted development
Building regulations
Metric or imperial (sorry...)
Here are some of the things we decided

Keep it within permitted development, the key part here being the 2.5m height rule
It's easy enough to apply for planning permission for a build like this, but I didn't really want to go any taller as we were already concerned about height / privacy / impact on neighbours
In terms of floor space we are easily within the '50% of your land' rule, but again we just didn't really want to go any bigger.
Overall dimensions were set at 9m x 3.7m (2.5m tall) and 30 m2 internal area
I do plan to apply for an LDC at some point (which will probably make it easier to sell the house at a later time), but as yet I haven't got around to that. It's better to do it before but it can be done retrospectively and I am not too concerned about it
I have spoken to local planning officer and taken him through all aspects of the build and he is happy with everything. Based on my plans he has confirmed that I would be exempt from building control (the key part being the wall build up and compliance to fire regulations)
If you read the building regs, it does actually state that if you sleep in the room then it needs to be controlled (i.e. the building would not be exempt), whereas permitted development is a little more specific about 'sleeping' and it goes into detail about 'self contained accommodation' and the use of it being 'incidental to the main house' etc
Despite what the building regs say, my local planning officer does not have a problem with the odd weekend with guests sleeping in there, as long as its not a full on permanent granny anex.
and that is kind of the plan, to have a workshop on one side (4m wide) and an office / entertainment space on the other side (5m), which can also double up as a place for guests to stay on odd occasions.
We have planned for a small toilet in there, which is the main reason why I got into looking through these particular aspects of the regulations
I did a few basic renderings of the view of the garden room from our house and also from the neighbours house - I also tried adding a small 'topper' on top of the fence to help with privacy, which seems to make a big difference. That side of things is irrelevant now anyway, as we have now planned to have a pergola and trellis running all the way along the fence line. That essentially sorts out the privacy thing.

By the way, it was my wife that added the toilet, and hence extra complication, and it was also her that suggested the pergola and trellis stuff - because life is boring when its easy right?.... 

The main reason I keep going on about privacy is because the land is on a slight slope, and by the time you put in a level building it ends up about 300mm higher than the land at one end. This higher end happens to be at the end next to the neighbours fence. There is also a rule about decking being no higher than 300mm. I am just generally trying to keep everybody happy.

anyway, here are a few pictures to add some context.

oh yeah, quick word on metric versus imperial, in a nutshell, for those that don't know, building materials are supplied in a mixture of metric and imperial sizes, meaning they are essentially incompatible. It becomes a key part of your planning for this reason, mainly because you want your sheet goods to fall on your studs, but that doesn't work if you use imperial sheathing on outside and metric plasterboard on inside (for example). I won't open this box here (oops too late), but in a nutshell, my particular solution was to work in metric, which normally means you have to rip down your OSB which only comes in imperial, HOWEVER, you can get 11mm OSB in metric. Alternatively, you can get your local timber yard to rip down imperial sheets before they deliver them (they will probably do this for free). Can you do this yourself? yes. Is it fun, no  anyway, I ended up using cement board, to meet fire regs, and this is supplied in metric which fits perfectly onto my studs, so it didn't matter in the end.

Martin

View from inside neighbour house:





view from inside neighbour house with proposed modified fence:





Overall view and plan for services (water, waste, power, data)






plan for wall build up to meet fire regs (although wall is now 125 x 50 C24 with 100mm PIR):


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## Molynoox

*Feb 2021 - Groundwork and Layout*

The goal with this stage was as follows:

remove trees / bushes
reduce the height of the ground on the left hand side such that the building can be sunk into the ground slightly and hence reduce its overall height above ground level on the right hand side.
Mark out the outside perimeter of the building such that it's ready for the installation of groundscrews (there are 28 in total, 4 rows of 7, or 7 rows of 4 if you prefer... )
Stump Removal
I was quoted £300 for tree stump removal, and I had 3 to do. Of course that meant doing it myself despite having none of the knowledge, skills or tools required. To get it done I used (primarily) a Makita cordless reciprocating saw, a Titan chainsaw (which I bought for the occasion, £50 was cheaper than £900 so it felt justified), and a 4ft wrecking bar which I found to be a mission critical bit of kit. A digging bar might be even better but what I found was that something heavy and pointy was needed to dislodge compacted mud, grit and stones from around the roots, allowing you to get your power tools in and cut the roots. I know you can hire these stump grinder things too but I looked into that and they seemed to be quite expensive and also quite spectacularly lethal looking, especially for somebody like me that has a habit of finding the most dangerous way to achieve each task. I can't believe I would have any feet left if I was to hire one of those. Stump remover, and stump creator, all in one go. I will stick to my metal stick.

Excavation
You can see from the pictures that I managed to excavate down about 150mm on the left hand side - this was quite a lot of work with just shovels but it will make a nice difference in the long term having the threshold for the main bifold door closer to the ground.
In terms of tools for this task, I bought lots of different shovelly items (not knowing anything about what was really best) and two of those became invaluable:

Mattock: I couldn't have done it without a mattock. I bought this recently and now can't live without it. It's a really brilliant tool. There are so many different ways of using it too. It makes the ground feel like its made of cheese, even when its rock hard and full of horrible stones and roots.
Round point, long handled shovel: also brilliant. The long handle saves your back, and the angle on the shovelly bit (the head?) means you can sort of skim across the ground and remove a top layer. Its perfect for this sort of task. But you need the mattock too. I like Mattocks, did I mention that?

Layout
I worked from a rough outline in order to excavate, but I needed something more accurate in preparation for the groundscrews being installed. For this task I made some 'batter boards' as an experiment. They worked reasonably well, but were not really strong enough for me to consider them a perfect tool for the job - they were a bit ricketty. Having said that it's nice being able to adjust each line by a few mm and get the outline perfectly square. I have since bought some fencing pins which I think I now prefer for doing marking out work.

You may also notice my home made giant square, I did consider buying a folding square but I was trying not to buy things I didn't really need. I made the hypoteneuse 2m which gave me sides of 1.414. Making one myself had the added benefit of making me feel clever, although the effect only lasted until my next mistake. Can't remember what that was but they are fairly regular.

Finally, for the overall building outline, I calculated the theoretical hypoteneuse (haven't written that word for 30 years and then along come two at once) as 9730mm and was then somewhat amazed to find both diagonals of my marked perimeter measured exactly that on the first try. I even took a picture I was so excited. I guess the home made square is pretty accurate. Probably just got lucky.

Here are the earliest pics of the garden I could find:





Mid-groundwork phase:








The blank canvas





Excavation mostly complete





Layout work





homemade batter boards


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## Molynoox

Layout complete and ready for groundscrews 





Evidence of my flukey yet perfectly square layout - 9730mm


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## Molynoox

*Apr 2021 - Install the groundscrews*

At this point the project became very real, and also very exciting. I had been researching and designing garden buildings for a few months previous to this point, and all of a sudden it felt like we had moved out of the world of theory and into the world of construction. This was also the first real financial commitment, having spent about £2500 on the groundscrews, so there was no turning back now.

The whole family (and the neighbours) were fascinated by the process of these giant screws going into the ground. They are quite comical to look at, they really do look like giant screws, and it could only have been better if they used an actual giant screwdriver to insert them! 

These are 1200mm long groundscrews manufactured by Radix, although I bought them through a company called GBGS which included brackets for the tops and installation by a professional crew. I spoke to about 5 different companies before selecting a supplier. I can't remember the exact specifications but each screw will support something crazy like 1000kg, I think even more actually. They are spaced 1.5m apart which seems to be pretty standard practice for all groundscrew companies and in fact all 'pier' based designs seem to use this rule. I will include a picture of my base design showing how the bearers sit on top of the groundscrews and take the main loading, and how the joists connect to the bearers and distribute that loading through the floor. I did do some research into joist lengths using span tables and such like, but I am well under the maximum allowable lengths for the joists so I'm hoping the floor will feel strong enough. I used doubled up 4 x 2 for bearers and single 4 x 2 for the joists, which are on 400mm centres. I hope I got that terminology correct, I am pretty new to construction having worked in automotive engineering all my life so I might sound a little bit like an silly person when it comes to this stuff.

Installation took about 3 hours start to finish, and the process is as follows.

They first scanned the area for electrical cables using a handheld 'CAT' tool. (you can't scan for pipework unfortunately so if you want to avoid those it's just guesswork)
They then made pilot holes for each screw with a large pointy metal bar.
Then they used a hose to spray some water into the hole and loosen the ground up, they explained that this made the screws go in much easier.
Then they insert the screws using a large specialist power drill (it probably has a proper name) - the big stalk you see sticking out to the side by the way is to stop the drill counter rotating, they brace this against the other groundscrews.
They use a post level to monitor for plumb as the screw is going in and adjust as needed, and use a laser level with bleepy device to set the height. They also agreed a 'datum' with me of 50mm above ground level which they set from the highest point of the land and then set all the other screws to that exact same height. I went round with a long level after they had left and checked every screw and they are all spot on
Incidentally I have just bought a large metal pointy stick of my own to make some pilot holes - I am going to be installing some self-install 800mm groundscrews to support the pergola and deck. I also picked up a post level for £3. I dont have the fancy big drill so I have purchased the manual self install tool for £45, this is basically just a large T-bar

Comedy screws and comedy big drill





Hand tightened first















All done





Notice that I didn't quite get the land perfectly level beforehand, so the next day I got the spade out again and levelled the land around any screws that looked too close to the ground. I ended up with about a 50mm air gap underneath each screw which is about as good as you can get on a permitted development build due to the 2.5m height restriction.


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## DrDarren

Really enjoying this thread!


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## Molynoox

Thanks drdarren, pleased to hear it. Starting to feel I was adding a little too much detail, as is often the case with me...  but i suppose people can always just scroll through to the pictures.


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## Inspector

When I was reading and got to the first picture of the ground screw I thought it was a photoshopped joke as they are unlike any I have ever seen here.....but no! That is what you actually used.  Pretty much all the ones I have seen look like these. Videos Screw Piles & Helical Piles - Ready to Build on Immediately! A round split plate pulled to a single turn helix and welded on in the factory. Doesn't matter if they are the little 3 foot ones or the 20' or bigger ones. The six I used for my decks were 10' long to get below the frost line.
Nice project and the detail is welcomed.

Pete


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## RobinBHM

the rendered drawings indicate cedar cladding on sides and rear -are you doing that, as I was wondering if you could clad those sides with cement board and paint or use box profile.

the other thing I wondered is the structure doesnt seem to have any plywood sheathing -only plasterboard and versapanel -are they suitable for use as sheathing.

you structure is a fair size and would be subject to a fair wind load so lateral stability will be important -plywood sheathing provides an important function in that regard

across the front there are only fairly small returns -those along with the centre section will need to provide lateral stability preventing wind load from those sides.

lovely looking project


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## Molynoox

haha Pete, I should have added the comedy giant screwdriver. Funny you make that comment about not seeing this type before, my research threw up 5 or 6 companies and only 1 of those used the type you are familiar with, and that was mostly for large construction projects it seems. Were yours really 10 feet long? that is massive! I thought frost line was way higher than 10 feet?


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## Molynoox

RobinBHM said:


> the rendered drawings indicate cedar cladding on sides and rear -are you doing that, as I was wondering if you could clad those sides with cement board and paint or use box profile.
> 
> the other thing I wondered is the structure doesnt seem to have any plywood sheathing -only plasterboard and versapanel -are they suitable for use as sheathing.
> 
> you structure is a fair size and would be subject to a fair wind load so lateral stability will be important -plywood sheathing provides an important function in that regard
> 
> across the front there are only fairly small returns -those along with the centre section will need to provide lateral stability preventing wind load from those sides.
> 
> lovely looking project



Hi Robin, thanks for the comments, really appreciate it.

The renderings are not accurate for the cladding, I will have Cedar on front and left side, and some cheaper alternative on right side and back because it will never be seen (box section like you say, or cement board cladding - your comment does make me wonder if I could have just painted the cement board sheets which I have already put up?? hmmm.... I like the metal box section stuff the most, but I have no idea how to fit that around the window which I have at the back, I feel like the lengths of cladding will be easier to fit around the windows.

I think the versapanel (actually I used Fermacell in the end) is just as strong, possibly stronger, than OSB. I am saying that from memory from when I researched all this stuff, so could be wrong. Well, it sounds like I might be wrong from what you are saying... The structure does 'feel' incredibly strong though, it is 5 x 2 studs, on 400 centres, which is pretty thick timber with tight spacing, with noggins, and 100mm PIR, which is also spray foamed in around all edges of all PIR boards making it massively stiffer than before the PIR went in. I also used one million screws, some of them were engineering screws. I know that is not empirical, but it does feel like it's made of concrete and not wood.

regarding your final comment, yes, I totally agree with you about that one - one of my regrets from the design phase - I put in glass without really thinking so much about lateral stability, focussing only on vertical strength. If I do another one, I would ensure I leave a sensible nominal distance (something like 500mm or a metre) between all apertures - I would need to think about that one some more to get a value to work from. But I think the fact I overengineered the materials and construction side a little gives me confidence that it will compensate for that.

Hope that didn't sound defensive, I actually really appreciate the feedback, I am hoping to learn from people like you so comments are welcomed.


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## Molynoox

I forgot to add the pictures of my base design with groundscrew placements, I know some of you were not able to get to sleep last night because of that, so here they are:

This is the first design, which had three rows of bearers and 21 screws in total





This spacing was in line with span tables for floor joists, but wasn't flying with the groundscrew guys who recommended 1.5m spacing minimum for their groundscrews, in both vertical and horizontal (or X and Y axis might be a better term). So here is the modified design which they were happy with; 4 rows of bearers and 28 screws in total:






Martin


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## Inspector

Molynoox said:


> haha Pete, I should have added the comedy giant screwdriver. Funny you make that comment about not seeing this type before, my research threw up 5 or 6 companies and only 1 of those used the type you are familiar with, and that was mostly for large construction projects it seems. Were yours really 10 feet long? that is massive! I thought frost line was way higher than 10 feet?



Well when Searching from here the ones you’re familiar with don’t come up at all unless I look at the Images. Mine were actually about 11’ or 12’ long when they picked them off their truck to drive them in. They were the heavier of the two kinds they brought. The 2 3/4” were to light to drive through the rocks and boulders to get to depth. They were 3 1/2” or 3 3/4”. The alternative to the screw piles was to dig the 10’ and use rebar and forms to make concrete piles. There was no way I was going to go through that expense. The smaller helical piles would have been $275Can each and the bigger ones were $350Can or 375Can, can’t remember which. And yes the frost line can get that low, that’s why they have to be 10’ deep so they don’t heave. In about a month it will stay about zero or lower getting to -40C and we’ll still get frost some nights at the end of May.
Pete


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## RobinBHM

Molynoox said:


> Hope that didn't sound defensive, I actually really appreciate the feedback, I am hoping to learn from people like you so comments are welcomed



not at all - I just mentioned it because lateral stability is often overlooked.

if insulation is cut a bit undersize and foamed in, it really does make the studwork rigid - I built a garden office and found the same thing - once the insulation was in, it became really rigid.

If you use box profile, it’s easy to finish around windows: cill projection at bottom, side cheeks at the sides and at the top, the box profile comes down a bit over the frame to act as a drip and a trim fits up to closes off the battens.


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## Molynoox

cheers Pete.
Robin thanks for the tips on the box section, I will do a drawing and get back to you to confirm I understood it. That will be in a few weeks probably  
I wondered if the noggins were even needed if the PIR was foamed in like that - like you say it makes a mega difference to lateral rigidity.

Martin


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## Molynoox

*Apr 2021 - Beam Calculations (for above the doors)*

I spent way too long looking into different options for door headers. I was a little paranoid about deflection as I didn't want to have any problems with the doors working properly over time. I have heard of a few people that have had issues with bifold doors and the root cause seems to come back to a combination of:
1. the door header not being suitable for the door span + roof loads
2. the sensitivity of the door to vertical deflection (but reason 1 seems to be the big one)

In addition to this, changes in the weather through the seasons can (I have heard) cause flex and movement which can lead to issues. My doors are alu so that means theoretically more stability versus PVC, and hopefully less issues, but the main reason I selected alu was for the sharper looks (if I'm honest). So... operating from the assumption that vertical deflection is the true nemesis of bifolds this became the factor which I needed to focus on and my mind was set on giving my lovely new doors a stress free life via a suitably deluxe door header experience. This meant doing a bit of research into what my best options were.

Results from my research
Unfortunately, most of the good guidance I found was for multi storey buildings and hence they were often coming up with solutions that would be not be suitable for a garden room. For my particular application, these recommendations would be either:
1. overengineered in terms of strength and cost
2. cause me issues on overall building height
3. or both

Mildly relevant distraction #1:
Regarding the height thing, when working within permitted development you need to keep everything under 2.5m (when building within 2m of the boundary) and for that reason you really need to think about what you are doing every step of the way. For example, assuming 2000mm for your door height, that leaves only half a metre for the base, the headers and the roof (not to mention the air gap under the building, and possibly even your floor boards depending on how you build it).

Anyway, I'm getting distracted, the point is the only other guidance I found for header selection / header design was pretty anecdotal and didn't seem to have any theory behind it. That isn't necessarily a problem, but on this occasion it wasn't giving me enough confidence to make a decision, considering the potential impact of getting it wrong (fiddly / sticky doors of annoyance).

The cunning plan
So... logically, I decided that I would leverage my complete lack of structural engineering knowledge to manually calculate the beam deflections for all of the options available. So here are the options I considered:

1. Doubled up 6 x 2, C24 timber
2. Flitch beam (C24 timber and steel 'flitch plate' sandwiched together)
3. I beam (sometimes known as a H beam or a 'universal beam')
4. RHS (rectangular hollow section)

Note: I did not include concrete lintel or glulam beam, for reasons which I honestly cannot remember, and there may be other options which I dont even know about, that I am hoping people will point out to me.

My plan was to use the below formula to calculate the maximum deflection on the beam. I would still of course have the problem of not knowing how much deflection was acceptable for my particular bifold door, hmmmm... HOWEVER I would be able to COMPARE them all







Mildly relevant distraction #2:
I did contact some of the door manufactures to find out what sort of deflection they think their products could handle, or even what headers they recommended for different spans - but alas, nobody wanted to commit to anything specific, other than to say "computer says no" or "zero deflection required" which is of course theoretically impossible, even if I made it from diamond.
Note: making it from diamond would represent a significant cost save for the build, considering how much I'm planning to spend on materials and 'essential' tools so far)

Mildly relevant distraction #3:
Note that there are lots of different formulas for this sort of thing, but the one above should represent worst case for my door header because it assumes the beam is simply supported at either end (in reality it has lots of engineering screws holding it in place along some of its length and also has the roof load partially distributed either side of the 'fulcrum' too, which I imagine restricts the movement - not that I know what I am talking about). Oh yeah, please note that I am absolutely NOT qualified in this topic, and everything I say should be considered as science fiction, even the science part is pushing it a bit.
I will point out though that I am lucky enough to know somebody that does know what he is talking about, and he checked this over for me and helped me with some of the calcs, so it isn't completely worthless. As a minimum I think it gives a good indication of how the options stack up against one another. Worst case its a bit of fun, and a good opportunity for everybody to laugh at my mistakes.

Variables






The legend in the pictures explains what the variables are, so I wont double explain those, but it is worth noting that the values for youngs modulus for each material can be found online in the so called 'blue book', as can the values for moment of inertia (which is specific to each shape / cross section) - you can calculate this if you want to, but its easier to look it up. I vaguely remember us covering how to do this in my mech eng degree, but that was 20 years ago and I was rubbish at it then and suspect even crapper now so much prefer standing on the shoulders of giants. Oh yeah, 'w' or roof load is the other funny one. I think for that one I calculated the weight of my entire roof (timber, insulation, EPDM, chipboard) and then added some for static snow load, and finally I think some for dynamic load for people / person (me) walking on there. I also divided the numbers by two because (approx.) half the load is on the front wall and the other half is on the back wall (my side walls do not support any load) Honestly can't remember exactly how I got that number, but as I say all my assumptions are clearly shown in the workings so as not to mislead anybody into how I got the overall deflection results. Looking at these numbers now, we have 14 N/cm which is 1.4kg per cm, which is 140kg per metre - so that 'feels' in the right ball park for the amount of load along that beam.
Finally, regarding variables, you will notice the slightly hilarious use of 'cm' as a unit. I am advised that the golden rule with SE calcs is to pick one unit and stick with it, and because a lot of the numbers provided for free in the blue book are in 'cm' it makes sense to use cm throughout. 

How I will contextualise the results
Seeing as I don't know how much deflection is tolerable by the doors, due to the fact it is a secret (not disclosed by the door manufacturers), I need a way to contextualise any numbers that pop out of the calculations. I am clutching at straws a little here, but I did find some rough guidelines that I think could help put the deflection values into context: I understand that some people work the following rule:
• <2m span = doubled up 2 x 6 timber is ok
• >2m span = metal beam required (or you could use thicker timber, but you can't simply add in 9x2 headers when you only have 2.5m overall building height to play with - so we end up in metal beam territory once a 6 x 2 isn't strong enough)

So, I will use a doubled up 6 x 2 timber as a sort of baseline solution that is 'probably' acceptable for a 2 metre span. Considering my span is 2.4m, I know that any alternative designs only need to be say 20% stronger, for the same constrained / max 150mm header thickness. (I think I mentioned this already, but I cannot just simply add thicker timbers and be done with it, due to the 2.5m building height restriction. That in itself is the ONLY reason for doing all this faffing around - I am fixed with 150mm max for my header)

The results
I will include some extracts below from my summaries for each of the 4 options so that you can see my assumptions (mistakes) in all their glory. As you can see, the timber option (for my 2.4m wide bifold) gives 3.4mm deflection (in the middle), and the metal options are far stiffer ranging from 0.71mm to 0.34mm deflection.





















Below are the full workings in excel.





The decision
So to cut a long story short (oops too late for that) I have decided to use doubled up 6 x 2 timber for above the french doors which have only a 1.6m span, and a flitch beam for above the bifold door which has a 2.4m span.

Factors influencing the decision:
COST
From a cost perspective timber is cheapest (about £50), and all the metal options work out in a similar same ball park, although flitch was cheaper than the other two metal options by about 30 or 40%
STRENGTH
Again, all the metal options are basically the same - as a minimum they are 4 times stiffer than timber, and if we work from the assumption that the timber option is good enough for a 2m span, then we can conclude from the numbers that the metal options are all way stronger than needed for my 2.4m. So, for my span, strength is not really a factor when choosing between the metal options.
WORKABILITY
the primary reason for choosing flitch beam over i beam or RHS was the fact that the flitch beam gave me a timber surface on both sides, which is nicer to work with (attaching cladding on outside or plasterboard on inside). I dare say flitch beam is slightly more hassle to erect than RHS or I beam because you have to drill holes in the timber and bolt it all together, which takes time, but its probably 2 hours of work to construct and install a flitch beam versus 1 hour to install RHS or I beam so probably not significant in the grand scheme of things.

Mildly relevant distraction #4: I just checked with future self, and I / he has confirmed that the flitch beam did take about 2 hours, not including the 30 minutes spent staring at it proudly afterwards, or the 15 minutes spent explaining it to my (completely uninterested) wife

Summary
Overall I believe flitch beam to be the best option for this application, but I reserve the right to change my mind later, probably when its too late. See below for some top secret pictures which I took from the future.











Cost wise we are looking at about £100 for the flitch plate, which then gets sandwiched between two timbers to create a flitch beam. Note that the delivery costs for these things are huge (prohibitively so), so I picked mine up in my A-team van as the place was only about 40 minutes away. You will also need some bolts too. And wood. Under £200 'all in' I guess, which feels like good value if it keeps the doors working properly. 

I am sorry for the length of that post, I find it hard to filter and I also find it hard and distinguish between useful and useless information. But, one man's trash is another man's treasure. Maybe that means my garden room could actually be worth something in the future.... :-D

Martin


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## MARK.B.

Looking good so far, those ground screws made me chuckle thinking about if they were phillips or pozi drive. Please do not stop posting detailed write ups of what you are doing,I find them interesting and with pictures they help to explain the process much more clearly


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## Fitzroy

Brilliant, that’s exactly how my wind works and why it takes so long to get anything done. Overthinking from first principles as you have zero experiential learning to draw from.


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## Molynoox

Mark, I will do - thanks for the positive feedback.
Fitzroy, brilliantly summarised, that is EXACTLY what's happening!


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## Molynoox

*May 2021 - Trench for Services*

The goal with this stage was as follows:

1. Design a trench
2. Dig a trench
3. Install services in trench
4. Backfill trench
5. Dispose of excess dirt in the neighbours garden (in the style of The Great Escape)

So this was yet another topic which I know absolutely nothing about and hence needed to spend some time researching it.

Bathroom scope creep
Originally this was just going to be a trench for power and internet, but then my wife had the idea of having a bathroom in the garden room (doh). I admit that I resisted this option furiously to start with because I didn't fancy the added complication on top of all the other things swirling around my head with this project (pretty much every aspect was new to me at this stage). But after some thought I realised she was right, if I don't do this now, I will never learn, and anyway "how hard can it be".... (lol)
The other aspect to consider is that adding a bathroom adds a lot of value (so I'm told), not that we are selling the house right now, but for the 'small' additional effort and cost, it can make this project a much more convincing investment. But ultimately, it wasn't property value that was driving this decision, it was a combination of the following:

If we do have guests stay over on the odd occasion, having a toilet inside the building is a bit of a game changer in terms of usability
The right hand side of the building is being designed as a space for my wife's maths tutoring, and also as a social space to hang out in, so it's handy for those
Our house has only one bathroom at the moment so having another is a big plus

Trench design
So I have 4 things that need to go into the trench:
1. Water
2. Waste
3. Power
4. Internet (x2, one as backup or use for an alarm)

Below is the plan view showing the routing needed for each service. Internet runs from the front of the house (not shown), power and water (red and blue) from about the middle, and waste (yellow) is from a drain (inspection chamber) which is situated in the garden adjacent to the rear of the house.






I had to calculate the amount of shielded power cable needed so it could be ordered, here is the sketch for that.






Guidelines
Looking online, there is plenty of guidance (mostly in the building regulations) about the necessary depths of each, but not so much about how they all live happily together in a single trench. It seems that common sense is the tool of choice for figuring out the best placement of each item inside a combined services trench, in terms of how they sit in relation to one another. Here are the guidelines I was working from after a bit of research:

Depth guidelines (based mostly on building regs)

Electricty depth (from the regs) = 500mm (to prevent unplanned spade / cable interaction electrification events)
Water depth (from the regs) = 750mm (to stop it freezing)
Internet: set at a similar depth to the power to keep it safe from humans with spades

Proximity guidelines (based mostly on anecdotal evidence and / or common sense)

Data: keep data away from power to prevent any electrical interference
Water: Keep waste and water apart (just in case one contaminates the other, which would really suck admittedly, but it does seem unbelievably unlikely as essentially both pipes would need to be leaking for that to happen). But that is the advice I managed to extract from the internet...
Avoid placing power or data below water and waste if possible - if I do get a leak this seems like the best disaster to have from the two options, but in grand scheme of things I doubt if this matters in the slightest
 
Note: CAT6 cable is being used for data / internet, which is apparently electrically / EMC shielded, so its theoretically possible that power and internet could go in the same conduit. However, this seems to vary depending on who you talk to, some people are saying you need to separate them, and some people are saying you dont need to, even for unshielded CAT5. So I played it safe and put data in a separate conduit of its own, as far away from power as I could, and also used CAT6.
Note: by 'conduit' I mean plastic water pipe
Note: by 'people' I mean mostly people on forums, but also some tradesmen that I know and spoke to about the topic. There may be better info out there but I couldn't find it

Other guidelines I planned to follow

Use shingle below and above waste pipe (this comes from the regulations, and is very clear, although from speaking to plumbers they dont always follow the regs it seems, again I think a bit of common sense goes a long way, but at same time some people may be cutting corners to save time and cost)
Use conduits for everything (other than waste pipe which just sits directly in the shingle without a conduit). This conduit is probably not strictly necessary, and although it does add a little extra protection, the main reason for them was to allow for easier fixing of any disaster scenarios that may occur. Any of the pipework or cables could in theory be replaced entirely without the need for any digging. In theory 

So here are two of the sketches I made when planning things out:











The final design didn't end up quite like that, partly because I added more separation between the power and data lines, and partly because the plumbers decided to go a bit freestyle jazz once they started work, and just did it their own way anyway.
Another modification was to have a layer of shingle both below and above the waste pipe. I ordered 4 tons of shingle, despite the plumber recommending only 1 ton - I got that wrong, but in my defence so did the plumbers as we used about 2.5 tons, so something in between would have been best. As a result of this I ended up with an unplanned gravel feature underneath my garden room.

Extract from the regs below shows how they stipulate a certain type of soil above the pipe, I decided that it would be easier to simply use more shingle rather than manually filter / select the soil, this guarantees no issues with stones / particle size.






Drawings for the plumbers
Because I had quite a few complex discussions with the plumbers about how this would all be done, I wanted to document it to avoid any communication issues in the future. At the time it felt like complete overengineering, but this later turned out to be absolutely critical for getting us all on the same page both before work starts and also during (when I could see that said drawings were not being followed).
One example of this is when I noticed them only installing a single combined conduit for power and CAT6, and this is not what I wanted. After a discussion when they tried to convince me that a combined conduit was ok, I showed the drawings of what we agreed and they had no option but to add a second separate conduit for CAT6.

The overall design which I agreed with plumbers was to use a mixture of an open trench, which I would dig for any routes in the garden, and to use a 'moled' trench for the runs alongside the house. Not sure on the terminology here, but they use a machine called a mole to install the conduits underground, which they then feed the services into. The moling machine uses a small pilot trench for the entry and exit points, which they dig manually with spades, but it 'tunnels' its way underground using high pressure hydraulics without the need for an open trench. You cant install a waste pipe that way, its too big, therefore I couldn't avoid a large open trench in the garden

The pictures below show the plan: solid lines are open trench, dotted lines are underground conduits installed by the mole. Green is internet, red power, blue water, yellow waste. Black boxes are the mole entry points



























Digging the Trench
I dug the open trench myself to save cost, and also because I wanted to learn and be able to do as much of the build as I could. I did consider doing the plumbing / drainage part also, but decided it best to see how the pro's do it, maybe next time I would try doing a bit more of the plumbing.

Again, the tools you select are very important here, and it is the same situation as with the initial groundworks in terms of which tools are the best. The mattock and the round point shovel were the winners for this job. I thought the normal square shaped shovel (with the cupped sides) would be really effective here once the mattock had loosened the ground, but that wasn't the case at all, it was the round point shovel that was able to extract the loose dirt from the trench once it was dislodged because the square one just couldn't penetrate the soil once it was loosened into big chunks.

Manual digging versus mini digger
From memory I think the trench took me about 3 days to dig, it is 800mm deep, 400mm wide and about 12 metres long. Not sure how long it would take with a mini digger, maybe just a day, so that may or may not make sense for you instead of manual spade work, depending on hire costs and how much you value your own time etc.

I will put some pictures of the trench digging in the next post


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## Molynoox

Marking out the sides with string





Marking out the placement of the waste pipe for the toilet





Down to depth for the first section of the trench





second section of trench now complete - the kink was deliberate as i wanted to keep the trench the maximum distance away from the groundscrews.





Mole evidence (you can see two of the three pilot holes in this picture, the shingle is also in place above the waste pipe)





The other mole entry / pilot hole (this one is for internet)





The mole machine





Internet (CAT6 x2) and power (SWA)





Same view from the future





Water pipe within blue water pipe conduit which is also inside grey waste pipe conduit





Foam insulation gets added later to the water pipe to stop it freezing
I am interested in knowing how people handle this type of situation with water pipes emerging from the ground in and around waste, what I did seemed pretty strange but I couldn't think of a better way of achieving what I needed.


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## Molynoox

Some additional trench pictures showing some other details:

Skip needed for removal of dirt - this ended up about 80% full just from dirt





The SWA cable was just pushed through the plastic conduit from one end and then popped out at the other end. The CAT6 was pulled through after first pushing through that yellow thing you can see. The yellow thing probably has a name (maybe a pull rod or something like that) and I borrowed it from a BT engineer that just so happened to be working on my house at the exact same time as I was doing the conduit stuff.





Ever wondered what 4 tons of pea shingle looks like?





Me making curved piping because I didn't want to go and buy some





The inspection chamber














The plastic conduit for the water pipe needed trimming down - easier said than done










I was a bit disappointed in how the plumbers had left this part for me, and how much work was required to finish it off. The conduit was way too stiff for me to be able to bend it into shape so that the water pipe came up under the building next to the waste pipe. So I needed to trim down the conduit so that I could bend the water pipe into position and then install it into a suitable 'pre-curved' piece of conduit. Trimming down the outer conduit with the multi tool was quite risky / tricky with the water pipe is already inside it but I got it done without accidentally cutting into the inner pipe.
An additional conduit was eventually added at the end and is made out of grey waste pipe. I custom made its shape using the mitre saw, super glue and gorilla tape. It has multiple compound angles in it so I couldn't just install a 90 degree corner piece. This didn't feel like something you would see a professional doing but I didn't have any better options I could think of.


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## Molynoox

*May 2021 - Bi-Fold Threshold Decision*

So around the same timeframe as doing the trench I also needed to decide what threshold I needed for my doors, which at this stage had just been kicked off.
I had a really hard time deciding on this one, because I wanted a low threshold bi-fold for a seemless transition between inside and outside, but at the same time I needed it to be weather tight (obviously) and hence perhaps needed to go with a rebate threshold.

I knew nothing about this stuff previously so I spent a fair bit of time looking into the pros and cons. I did a forum post about it actually and received some good advice.

This picture should give you an idea of what I'm talking about, a threshold is the bit at the bottom of the door above the cill where it meets the outside world - it is the thing that stops or allows things getting in and seals the building from the outside world.





The two types of threshold
For those that don't know (like I didnt until recently) there are two types of door threshold:

Rebated threshold - fully weather proof, but has a small lip at the rear side of the door to stop rain getting in
Low profile threshold - not as weather proof as rebated but doesn't have the lip at the rear meaning you have more chance of creating a seemless transition from outside to inside
See the drawings below which I managed to get from the manufacturers (note that the cill is not actually shown in the drawing).

*Low profile threshold*





*Fully weathered / rebated threshold*





The door suppliers typically play it safe and insist that you need a rebated threshold if the door is 'outside'. However, it is not quite a clean cut as that, because in reality, if your door is outside but is under a large canopy, it could mean that rain doesn't ever reach the door, or you may have a small canopy and some rain could reach the door, but not as much as if the door was unprotected.
Also, when you look at the design of the low profile threshold, it is actually pretty difficult to imagine water getting in, my reasons as follows:


There are two sets of brushes, these should stop drafts but also some of the rain I would imagine
There is a drip channel, meaning that if water does reach the cill / lower rail, it will simply drain out again
There is a rubber seal on the outside to prevent water even getting to the cill / lower rail area (Note: I didn't realise it had this rubber seal until after the threshold decision had been made, because it isn't on the drawing)
Lucky accident
Anyway, what happened is I couldn't decide so played it safe and ordered the rebated threshold. As it turned out the door company screwed up the order and delivered me a low profile threshold for both sets of doors (bifolds and french doors). This turned out to be a bit of a winner because I negotiated a £1000 discount, and at the same time I sort of got what I really wanted all along which was a low profile threshold - I think this will be much nicer if I can have a single level from inside to outside without the lip. Now that future Martin has seen the doors in the flesh I feel confident that this will be weatherproof, especially as I have a small canopy, but time will tell.

Ultimately, a low threshold is a compromised design because it relies on the little brushes and the little rubber seal trim to protect you from the rain, rather than a proper rebated lip which could be more robust over the years to come. But I will find out if this turns out to be a good 'decision' or not after a few years.

Cill size decision
Is it cill or sill? I see both spellings on line. Anyway...
One other decision to make at this stage is the length of the cill - there were two options with my door manufacturer, 90mm 'stubby' cill and 150 'normal' cill.
I ended up chosing the normal 150mm cill which turned out to be the right decision. Once you add the battens and cladding to the outside of the building, a stubby cill would actually be buried behind it! The 150mm was in fact only just long enough, but this is partly to do with the placement of my door / cill (which I had placed in the _*middle *_of the 5 x 2 stud walls). If you needed longer effective length on your cill to clear your cladding, you could position the cill and door further forward inside the wall - this placement seems to be a fairly arbitrary decision and you just get asked when the door installers arrive on site what you want.

I have horizontal cladding therefore a single layer of battens, but if you go for vertical cladding then you will need two layers of batten. This adds 25mm and could mean the 150mm cill was too short, unless you positioned the door a little further forward. Some of this stuff needs thinking about at this stage, hence why I am mentioning it.



Martin


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## MARK.B.

You were right in using the pea gravel,it serves to protect the pipework/cables by providing a cushioning effect against ground heave/movement should there be any, and in years to come when you have won the lottery and moved into a mansionthe new owner when digging a hole for a pond , will first hit the gravel which should alert them to the hidden stuff before doing any damage. Will you be fitting a drainage channel as shown in the drawing for a low profile cill ?.


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## Molynoox

Hi Mark, no I'm not planning on adding the drainage channel as shown on the low-pro drawing, I don't _*think *_I need it. I did spend some time thinking about adding an ACO drain along the front and looked at the options, but I decided that it isn't necessary. I will have composite decking in front of the building and this has gaps between the boards which is where the water will drain off. I do want to keep water away from the building of course, and I have ensured that I have a small gap in between the decking and the building to prevent water running towards the building. The decking is also angled at 1 in 80 gradient away from the building. The bearers for the decking is normal tanalised C24 but I'm planning on painting the tops of it in bitumen paint.


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## MARK.B.

To be honest i don't think you need it either, it would take a small flood to get high enough to enter through the door way.


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## Molynoox

*May 2021 - Wood Delivery*

Towards the end of May I received my main materials delivery
This was pretty much everything needed for the base/floor, walls, roof including wall and floor insulation (but not roof insulation, that would arrive later)











Mistakes

*Mistake 1*
I made a big mistake at this stage because I stupidly ordered it all together rather than staging the deliveries for when I actually needed the materials. I was lucky because I called the timber yard and they agreed to take back some of the stuff on the lorry and deliver it later when I needed it. For example battens, roof boards, plasterboard. Not only did I not really have room for everything in the garden but the plasterboard would probably have been damaged if stored outside, even if covered as I am sure it would have got wet at some point.

*Mistake 2*
One quite minor mistake I made was not really preparing for the delivery, I had cleared a space and erected a gazebo but hadn't put any bearers down on the ground to support it all, so that was done in a last minute panic when the lorry arrived, which wasn't much fun. I was lucky I had some wood I could use, otherwise I am not sure what I would have done.

*Mistake 3*
I didn't think about the build order and hence how I wanted to store everything. It is no trivial matter to get to a few lengths of wood which are stored at the bottom of a pile, handling wood multiple times, just to get access to things underneath it is a major time drain and something I would plan for much better next time. I may also simplify my wood length configurations - I actually created a little excel sheet when I was doing my wood ordering calculations, it took all the lengths which I needed and told me what lengths I should buy based on maximum utilisation and the price of each length (yes some lengths are cheaper than others per metre for some reason). For example, if you need 50 joists at 1.1m long you might think buying 2.4m lengths is pretty good going in terms of waste, until you realise you can do better with 4.5m lengths and save quite a bit of cash. Also, sometimes its worth buying a length that appears to give more waste, because if the offcut is exactly the same size as your noggin length, then that ends up being zero waste. So the spreadsheet worked all that sort of stuff out and hence I ended up with virtually zero waste but at the same time a stupidly complicated timber configuration (I think I had 10 or 15 different types of CLS timber). In future I would simplify a little. Also, big long lengths like 6m are quite annoying to handle, especially if your mitre saw stand is quite basic like mine and doesn't support long lengths very well, so all that stuff would be a future consideration and I expect I will simplify.

Screenshot of my basic timber optimiser






*Mistake 4*
The wood did get wet, because some of the timber lengths were 6m long and were longer than the gazebo. This meant the water ended up running into the main pile and getting a lot of the stuff at the bottom wet. Also, I didnt put the back on the gazebo and the water was able to get in sideways - not a lot but it built up over time. Because I have so much sat wood in a pile for quite a few weeks, the stuff at the bottom got a bit 'secretly moist' and ended up with a bit of mould on by the time I came to use it. So I ended up drying that all out in a makeshift rack and sanding it down once dry to get rid of any mould. I also bought a moisture meter to make sure it was all below 19% before I used it (I think that was the number I found on line for the moisture threshold). As it turned out it was mostly between 10 and 12% so it was fine and only took about 2 days to dry out.

Mouldy wood





Drying racks





Martin


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## Duncan A

Absolutely fascinating, astounding attention to detail and clear reasoning for your choices. Thank you for posting it.

Would a plumber's pipe cutter have done the job here, with less risk?".......Trimming down the outer conduit with the multi tool was quite risky / tricky with the water pipe is already inside it but I got it done without accidentally cutting into the inner pipe......"

I hope you've planned for a fridge in the garden room. You'll deserve a cold beer or two when this is finished!

Duncan


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## pils

How is your future self holding up?


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## Molynoox

Duncan A said:


> Absolutely fascinating, astounding attention to detail and clear reasoning for your choices. Thank you for posting it.
> 
> Would a plumber's pipe cutter have done the job here, with less risk?".......Trimming down the outer conduit with the multi tool was quite risky / tricky with the water pipe is already inside it but I got it done without accidentally cutting into the inner pipe......"
> 
> I hope you've planned for a fridge in the garden room. You'll deserve a cold beer or two when this is finished!
> 
> Duncan



thank you Duncan! glad you are enjoying it  plumbers pipe cutter is a great idea, unfortunately the water pipe had a large valve on the end and the outer conduit was not wide enough to slide over it, so i had to cut along the length of the conduit to get it off. I am starting to think i need a beer fridge in there, it's been hard work to be honest....


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## Molynoox

pils said:


> How is your future self holding up?



future self is feeling a bit worn down and has resorted to writing this build log in order to avoid doing the work he is supposed to be doing. At the moment my activity splits most days seem to be about 20% building, 80% researching, head scratching and decision making....


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## pils

Molynoox said:


> future self is feeling a bit worn down and has resorted to writing this build log in order to avoid doing the work he is supposed to be doing. At the moment my activity splits most days seem to be about 20% building, 80% researching, head scratching and decision making....


keep up the well though*t* out work...whilst ignoring your future self's hindsight.


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## Molynoox

*Jun 2021 - Base (Timber Frame)*

I was pretty pumped at this stage because it marked (in my mind) the real start of the build; everything else up until this point felt like preparation so it was good to finally do some work that felt like I was creating something instead of just pushing dirt around.

It was a very quick job to roll out the weed membrane and cut a few holes for the groundscrews to poke through. I just made 'X' shapes with a stanley knife and it worked perfectly. You can buy ground staples to fasten down the weed membrane but that didn't feel like it was needed here so I didn't bother.






Timber Base
I had CAD to work from, so I knew exactly what I was doing (lol). Even so that didn't stop me spending most of the day walking around and staring at the ground and figuring out where to start. Despite all that thinking time, I still screwed it up, almost straight out of the blocks (which was funny until I discovered just how difficult it is to remove 90mm nails from CLS). See if you can spot the mistake in the below base design.






Mistake 1 - no access for nailing
I concentrated on getting the perimeter in place first (correct dimensions and making it square), this felt like a good start (but it wasn't). The plan was to then build up the centre of the frame with additional bearers and joists once the perimeter was built because then I would know its the right size and shape. Unfortunately I didn't really think about how I was going to get nails into the joists, through the _*sides *_of the bearers. The perimeter is made up of doubled up 4 x 2, which gives a total bearer dimension of a 4 x 4, which is about 90 x 90mm. My framing nails are 90mm which means they will not pass through the 90mm bearers into the joists. So what I think I should have done was build the perimeter with *single *4 x 2, and then makes 3 sub frames (I call these cassettes but that might be made up terminology) and then slot these 3 sub frames into the perimeter frame. That would effectively give me a doubled up 4 x 2 around the perimeter once it was all together. You may need to look at the CAD screenshot to know what I'm talking about there.

Updated Base Design
What I have done with the CAD below is update the left hand side with the new design (orange and yellow) and the right hand side I have left as the original design (blue).






New Design
In the new design the orange perimeter would be constructed first, to get the perfect size (but not shape at this stage) and then the yellow subframes would be constructed and slotted into place. Once the yellow subframes are constructed, I would then make it square by measuring the diagonals and 'tapping' it into shape. Once both diagonals were identical I would throw a long timber down (diagonally) and fasten in place with screws to keep it perfectly square.






Old Design
In the old design, what I actually did was construct the blue perimeter first, with doubled up 4 x 2 for bearers, only then to realise that wasn't going to work because I couldn't fasten the joists in place. I don't think I actually fastened it ALL together before I realised but I certainly threw a few nails into some of the frame as I remember having to pull them apart.
*Note*: you could I suppose proceed with the blue design and use joist hangers _only _to fasten the joists in but

I didn't know if that would be strong enough
I wasn't sure how easy it would be to fasten joists in place using only hangers, without first fixing from the side with the nail gun.





Here is me implementing mistake #1:





Mistake 2 - groundscrew placement irregularity
The groundscrews do not always end up millimetre accurate in terms of their placement (they hit stones and harder ground and move around a little bit as they are going in). For this reason it would make a lot of sense to first (before building the base) measure the final placement of every groundscrew so you know what you are working with. I am estimating here, but I would say that the placement of each screw is accurate to within 10mm or so on average - a lot of them were within 5 or 10mm but the odd one was a little out by maybe 10 or 20mm. Doesn't sound like a huge amount but it does affect things, especially when two screws are out in opposite directions thus creating a compound error.
The final placements of the groundscrews have a dependency to the *size* and *location *of your base.

*Size of the base*
Ideally, you want the size of the frame to be exactly as you designed it (in my case 9m x 3.7m) but this might not be possible depending on how the groundscrews fall. In my case I didn't really think this through and hence built the frame before thinking about any of this. Fortunately it was fine, other than having to grind down the sides of one of the groundscrews becuase it was sticking out from the base a little even though all the other screws were perfectly in line with one another. 
*Location of the base*
You can shift the base around on the groundscrews to find the best compromise in terms of the location - you want as much of the bearer as possible to sit on the groundscrew and you want as little of the groundscrew overhanging away from the bearers as possible. So it's a case of messing around a bit to find the best placement.
*Note*: this is significantly easier (so I imagine) if you first build the perimeter and shift that into position rather than trying to move the entire base once its all built. I think I ended up using a club hammer to 'tap' it into position until I was satisfied (or until I got bored)
*Note*: it is critical that you have a cross brace on at this stage so you can manipulate the placement of the frame on top of the groundscrews and keep the frame perfectly square.
Note: one thing that future self has been telling me about is that any braces, for keeping things square or plumb, should be kept in place for as long as possible and should never be removed prematurely unless they absolutely have to be, even if you think other bits of the structure are keeping things square or plumb, they may not be. Future self is talking about that quite a lot, so I guess its important.

Mistake 3 - I need a base to build the base
This was a bit of chicken and egg, I needed a large flat surface to build the base. Ironically, once the base is built I have a perfectly flat surface of the exact same dimensions I need to build a base. Anyway, this wasn't such a problem in the end, I simply placed long timbers across a few of the groundscrews in order to give me the support I needed.
Note: if you have two people this would be a bit easier because you wouldn't need the support timbers; each person could simply hold the joist in position with one hand and then nail it into the bearer with the other hand (assuming a nail gun). Doing this on my own I needed a way to have the joist supported at both ends before I could nail it. Later on I discovered that I could use the already built subframes in order to build more subframes as each subframe was almost exactly the same size. So this worked fine, or at least it did once I had realised I could do it that way.

Joist hangers
Not sure if you need nails from the sides into the joists AND joist hangers, but that's what I did. I imagine joist hangers on their own would be enough but I didn't know so did both. Anybody know the answer to this?
In terms of assembly sequence, some people attach hangers to the joists then attach that 'joist / hanger' assembly to the bearer. Other people nail the joist to the bearer first and then attach the joist hangers. I personally attached the hangers to the joists first because I thought it would be faster in the long run. I made 10 or 15 joist / hanger assemblies, and then made a sub frame by attaching them to the bearers.

Joist hanger assembly station.;





Note that I made a little seat and a sort of wooden 'anvil' too because I found that a solid surface to hammer on made a huge difference to the speed at which the nails went in.

Stop Blocks for repeated cuts
I had quite a lot of joists to cut at the same length so I created a simple jig to allow me to do that on my mitre saw.








*Caution*: I would be careful if using a system like this; the timber base plate which I screwed onto the saw is what holds everything in place and keeps your cuts repeatable. I only used one screw on each side of the blade and although this felt quite solid, I think repeatedly banging long lengths of timber up against the stop block acted as a battering ram and moved the whole base plate by a mm or two. This meant that the joists were getting bigger and bigger each time I cut one until the final ones were maybe one or two mm bigger 
*Note*: My basic evolution mitre saw stand is cheap yet basic, and the in built stop block facility on it is almost useless because the range on the extending arms is quite small. Defo not criticising evolution for this because the stand is only about £60 and I think its good value but in hindsight I should have bought the Dewalt one at about £150 which has a far bigger range, and is just a bit nicer from what I can see

400mm spacing (not 400mm centres)
PIR is expensive and hence I wanted to maximise utilisation / minimise the waste. I am using 22mm floor boards, which fit together with a toungue and grove, and are glued together with a strong PU glue. For this reason I feel that the board edges don't need to fall on joists which gives me the freedom to place my joists wherever I want them. I made a 400mm spacer jig to help me get the spacing between joists accurate.






I will include a few more pictures in the next post as I have reached my 10 limit for this one 

Martin


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## Molynoox

In the below picture you can see the subframes. For some reason I am levering up one of the subframes, no idea why I was doing that, possibly to put more nails in, I don't know.






The below picture is a good representation of how I was constructing the subframes by the end. Note that this still isn't how I would do it in the future, because in the below you can see that I *wasn't* adding joists to the end of the run, instead I was utilising the longer perimeter timber to terminate the run (if that makes sense). This turned out to be problematic because in some areas I couldnt get access to punch nails in from the sides. Yes that's right, the exact same mistake from earlier. So if you look at the orange and yellow CAD from earlier, my improved design, you will see that each subframe has its own end joist, which could then be fastened to the perimeter from the inside. I would be surprised if anybody is following what I am saying here.... 





Frame complete and cross braces in place:





Attaching the frame to the groundscrews:




Note: to the left of the bracket (and also sticking out of the bracket) you can see the coach screws which I used to bolt everything together. I put in about 50 of these to tie it all the bearers and subframes together. I also used a forstner bit to create a rebate for the head of the bolt, so that I had a clean aperture for the PIR. It might be quicker to cut a tiny slot in the PIR in the future... 

Coach screws going in (I asked my wife to do this, just for fun - I think she enjoyed it)





Trimming one of the groundscrews:










you can ignore the floor boards and PIR, those are from the future and will be covered in the next post.
that's all for now

thanks
Martin


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## RobinBHM

Your calculations on beam deflection above the doors may or not consider:

The structure gets built and roof goes on before doors go in….therefore the dead load deflection will occur before doors go in

door frame is presumably a bit shorter than structural opening….so when you pack the frame, the dead load deflection does not impact on the door frame.

obviously live load, eg snow will impact.


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## Molynoox

Hi Robin,
that's an interesting point you make, I hadn't really thought about the fact that some of the deflection (dead load stuff) occurs before the doors are in place, and the rest of the deflection (dynamic - such as snow, people etc) occurs after the doors are in.
I didn't separate out the dead load deflection and dynamic load deflection in the spreadsheet, but it would be easy enough to do. My calcs show a combined (dead + dymanic load) deflection, representing worst case.
This still allows me to compare all the options and help me select best solution for my application. Or at least it convinces me that I'm selecting the best solution - a big part of me still thinks that a doubled up 6 x 2 with a 10mm gap above the door would be absolutely fine for 2.4m, despite me going a different route.
Martin


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## Tealeaf

Fabulous write up here Martin with some tremendous detail. I love the thought process and prep you have put in here. I'm looking forward to the next instalments!


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## Molynoox

thanks Tealeaf, appreciate the feedback - I'm glad its useful / interesting for you


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## Molynoox

*Jun 2021 - Base (insulation)*

Time to start installing the PIR into the base.

Utilisation
As I mentioned earlier, the apertures in the wooden frame are deliberately sized at 400mm so that (in theory) I get 6 x 400mm cuts per PIR sheet with no wastage (PIR sheet is 2400mm x 1200mm). My joist length was just over a metre, so I wasn't able to maximise the 1200 width of the PIR, but the 100mm off cuts I ended up with did get used in other places. PIR about £45 per sheet at this time.

Battens
The first challenge was making sure that the PIR stayed in place - it's not going to be effective if it drops down to the floor, it needs to stay put for it's life therefore I wanted something reasonably strong. There are a few different ways of doing this but after some thought I decided that the best option was to run long strips of batten underneath the frame. This stuff is pretty cheap and comes in 4 metre lengths so I thought it could be installed pretty fast too.
*Challenge 1*
I didn't predict this but it was surprisingly tricky getting the 4m long battens in place underneath the frame. Next time it would be better to put them there before building the frame, but not a huge deal, just took a bit of faffing to thread them through the groundscrew maze underneath the frame
*Challenge 2*
My 4 x 2 bearers are 95mm and the PIR is 100mm. If I nail the battens tight underneath the frame the PIR will sit 5mm proud of the surface. I spent a lot of time wondering if this would be ok, and if the floorboards could be screwed down on top and simply compress everything down flat. But I decided that was too risky, because if it does create problems it's quite a major fix to reverse out of it. In the end I used a simple spacer jig which I made in order to keep the batten 6mm away from the frame when I nail it in place.

Spacer Jig
I was pleased to discover that it was easy enough to hold the jig in place at the same time as pulling the batten upwards towards the underside of the frame, and then nail in from the top with a nail gun to fix it. I initially used 50mm nails for this, as battens are only 25mm, but in the end this was a rubbish idea because the 'toenail' method I was using meant that the screws were nowhere near long enough. I switched to 90mm and after a little experimentation with placement and angle, I was able to reliably get the nails in perfect. It was also very fast to do and I managed to do the whole lot in about 30 minutes (from memory).
Note: a 'jig' might seem excessive but I initially just used a scrap of 6mm ply and I kept nailing it to the frame by accident (sometimes the 90mm nails shoot off at weird angles when they hit knots). This turned out to be quite irritating, because it was quite tricky rescuing the ply spacer once sandwiched in between frame and batten. So the rebate on the jig allowed me to line it up with edge of the 4 x2 and keep the spacer part away from the nailing zone.











Cutting PIR
Anyway, once the battens were in place, I could focus my attention onto my next science project / exercise in overthinking which I like to call "how many different ways can I cut PIR?"
The candidates were as follows:

Jigsaw with specialist 'wavy' PIR blade
Method #1 but with additional home cooked blade guide jig
Non-specialist universal hand saw (rusty specimen found in the shed)
Specialist Bahco wavy blade hand saw
Specialist Magnusson drywalll hand saw (recommended by the internet)
Japanese pull saw
 
Items I considered but didn't test:

 Table saw with normal blade
 Table saw with specialist blade (the one that looks like a frisby with holes in it)
 Festool jazzy cutter (ISC240)
 Bread knife
 Hot knife
Note: I don't own a table saw and therefore option 1 and 2 would have required some investment to test it, hence why I didn't test it
Note: I had bought 10 or 15 bottles of spray foam because I intended to foam it all in place and try and get near perfect insulated panels . This means that if the pieces of cut PIR were too small it wasn't such a big deal for me, as the foam easily fills it. But if too big, you have no option other than to hack away at it and trim it down, which takes time, creates loads of dust and just generally sucks.

Method 1 - jigsaw and wavy blade
So this was very impressive and it cut through the PIR like it was made of erm... very non-dense things. There was almost no resistance as I pushed the jigsaw through the cut. I used this method for quite a while thinking I had stumbled upon the best thing ever, but then I started to get inaccuracies in the cuts. This was due to the long wavy blade wandering away from the cut - the top line along your mark was bang on as you just guide the saw on your mark, but underneath on bottom side of PIR it's very hit and miss. It usually starts very square to the cut, but as you get to the middle and end of the cut, any blade wandering gets worse and worse, and you can end up with an 80 degree blade angle by the end instead of 90 degrees. This means some parts of the workpiece can be 10, 20, maybe even 30mm out, and sometimes its 20mm too big, and sometimes its 20mm too short. So this was annoying me quite a bit, but I thought I could rescue it.

This is the jigsaw blade:





Method 2 - jigsaw and jig
I tried lots of ways of keeping the blade at 90 degrees, by building ever more complex jigs, and in the end the best of them (two timbers underneath the PIR to sandwich the blade) still wasnt good enough. The main issue was that I could get the blade to run at 90 degrees, but I couldn't get the PIR to stay perfectly in place, which it needs to if you are using a runner underneath. Also, it was a bit of a faff to line it all up top and bottom. I tried using clamps and timbers on top and stuff like that to hold the PIR down but in the end I just gave up and went back to method 1, before then getting frustrated and trying out method 3....

Below you can see my final attempt at a wavy blade jig. There is a timber on the floor that I was using as a clamp, and also some support blocks either side of the PIR which support the clamping timber. The two timbers in the middle create the groove for the blade.






Method 3 - hand saw
OK so this worked pretty good! Very fast and very accurate. Can't fault it other than one big problem; it creates loads of dust which gets everywhere (but it particularly likes eyes and mouths - those are it's favourites).

Method 4 - wavy hand saw
This saw is basically a big, manual version of the wavy blade I had in the jigsaw. I think this would work OK on maybe 50mm but trying to cut 100mm was way too much effort. Too much friction as the saw passed through the PIR. The good part of this method is the minimal dust (that is also a nice advantage of method 1 and 2). But overall this didn't work for me because it just didn't cut very efficiently

Method 5 - drywall saw
This was a recommendation from a forum post about cutting PIR, and the results were dissapointing, basically exactly the same performance as the rusty hand saw from the shed, except it was more flexible so actually wandered in the cut more than the rusty saw.

Method 6 - pull saw
I thought the thin blade and fine teeth could be advantageous, and hence worth a shot, but this method wasn't as good as the normal manual push saw.

Conclusion
So after all that, in terms of accuracy and speed, the best way to cut PIR turns out to be a rusty hand saw. 

Note: for fiddly bits (like cutting notches, grooves etc I used a padsaw in addition to the method used for the straight cuts
Note: I used respirator and goggles at all times, apart from when i wasn't using them, and in those cases I got PIR dust in my mouth and eyes and promised myself to never remove mask and goggles. Until next time.

Pictures

The battens nailed in place





Some spray foam action





Done





Water and waste pipe detail





Martin


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## xLrc

This looks fantastic and very well thought out. I've been watching a lot of garden room videos recently so seeing all stages of the build is really interesting to me. 
I don't know if you've considered it, although at even more expense, it might help with the PIR insulation to get a really tight fit. https://gaposhop.com/
I saw Robin Clevett using it on a video and it really does look useful.


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## Molynoox

xLrc said:


> This looks fantastic and very well thought out. I've been watching a lot of garden room videos recently so seeing all stages of the build is really interesting to me.
> I don't know if you've considered it, although at even more expense, it might help with the PIR insulation to get a really tight fit. https://gaposhop.com/
> I saw Robin Clevett using it on a video and it really does look useful.


thanks! appreciate the positive feedback.
I've watched a fair few garden room videos myself  I will keep making my write ups and by the end we will have a little book reminding me of all my mistakes.
thanks for the heads up on the gapotape, appreciate that - I also spied Robin using it (I am a huge Robin fan, he really is the king of carpentry isn't he) and actually I did plan to use it, but only in the roof to hold it in place. For the walls, I spray foamed those in and they are every bit as airtight as they could be. I didn't use it in the roof in the end (for various reasons that I am sure I will expand on by the time I get to that chapter  )

Martin


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## Molynoox

*Jun 2021 - Base (floor boards)*

The floor boards I bought were 22mm Cabershield, 2400 x 600mm, tongue and groove. Egger Protect is a very similar thing from a different company. I also bought a few tubes of the recommended Caberfix D4 PU adhesive (but I suspect any PU glue would work). It's a nice product, both sides are waterproof but the top is grippy to prevent any banana skin moments and the bottom is slippy to make it easy to slide into position. The T+G joins are just exposed chipboard and are not waterproof.

Notes on build sequence
I decided to build the floor next, rather than later once the walls are in place.
The reasons being as follows:

I bought a weatherproof flooring that in theory can be exposed to the elements for up to 60 days
I wanted to have a large flat surface for building the walls (I figured that if I didn't put down a floor, trying to tiptoe around on top of the frame and trying not to stand on the exposed PIR would be next to impossible)
Laying the floor
I knew the base was perfectly square (having measured the diagonals) so I was hoping that the boards would fit together perfectly. It turned out to be pretty straight forward to lay the floor, apart from the one fiddly bit near the water pipe and waste pipe, but even that was pretty simple. The glue gets applied to the tongue and groove, and also the timber frame before placing the board down on top of it. One thing I learned with the glue is it was really hard work squeezing it out of the tube and I was getting hand cramps doing it for hours on end. Then I realised I could cut a bigger hole in the end of the tube... Duh! That made things a whole load easier.
As I mentioned earlier, I didn't worry about placing the joins of the boards on the joists or the bearers. The board is 22mm and is plenty strong once glued together. Well, at least I think it is but time will tell.
You will notice that I left about 100mm of the frame 'un-boarded' at the front. This is because I planned to sink the door frames down below floor level. This effectively gains me 22mm of building height, sort of (I only have 2500mm to play with under Permitted Development). Little details like that can all add up and make a difference because I planned to have a vented cold roof (with 100mm PIR), and for that I would need 50mm more height than if I just did a 'hybrid' roof for example (no air gap above PIR). So you need to get creative and think about ways to gain that extra height, or more accurately you are trying to control the height build up.









_Wasn't expecting that to work....._












_Glue detail_





Waterproofing
I did make quite a few attempts to keep the structure dry during the wet weather using a series of tarps, I had some success but I would say I had about an 80% failure rate; most days I would take the tarp off to find it waterlogged underneath.
It's not easy with a totally flat floor because the water just sits on top of the tarp like a pond and if there is even a pin prick sized hole in the tarp then its party time for the water and the entire surface will be soaked underneath. I think the problem is that the tarps, which were about £30 from screwfix, were not strong enough to withstand normal use - when I was moving them into position they would sometimes snag on bits of the structure like the corner of boards for example, and then the tarp is effectively ruined - even if you can't see the hole, it's there! If I did it again I would think about buying a much thicker tarp - the problem with that is that it would be quite a big object when folded up and where are you going to store it?...
So it's either a strong tarp, a big gazebo, a scaffolding structure, or just leave it exposed to elements and cross your fingers.

_First attempt at waterproofing_




_Second attempt at waterproofing_




Problems with the floor
The floor did get affected by the weather unfortunately. It was a little swollen at the joins where the rain had penetrated into the chipboard and caused some expansion. I had to use a power plane to flatten this all, and in the end I got it flat, but this took me 2 or 3 hours to do and was pretty messy and noisy. We did have some incredibly heavy rain during June and July this year and as a result the floor was getting pretty soaked so I guess that contributed. The other thing is that the company that make it (Norbord) recommend scraping off the excess dried glue ONLY once the structure is watertight, but I did it straight away because I wanted the flat surface to build on. I don't think it is practical to leave the glue in place because it creates quite big ridges in an otherwise flat floor, which as I say I needed to build the walls. The only things that I can think to try next time is:

try a different brand flooring (Egger) and see if it is any more weatherproof
*try *pushing the boards tighter together so the join line is thinner and less vulnerable
leave the glue in place until structure is watertight
buy much better (stronger) tarps
hope for less rain
Mistakes
Storing the boards by stacking them at the right hand edge of the base / frame was problematic because I had to move them halfway through laying the floor - no trivial task! I should have stored them at the front edge. I couldn't simply board the right hand side last either, because I was using the offcut from each run to start the next run, if that makes sense.
This seems to be a general theme for me, not fully thinking through where I am storing materials and why. Storing something 2 or 3 extra metres away from where it is needed doesn't feel like a big deal at the time, but when you are carrying 50 items those extra metres walked all add up....


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## xLrc

Molynoox said:


> thanks! appreciate the positive feedback.
> I've watched a fair few garden room videos myself  I will keep making my write ups and by the end we will have a little book reminding me of all my mistakes.
> thanks for the heads up on the gapotape, appreciate that - I also spied Robin using it (I am a huge Robin fan, he really is the king of carpentry isn't he) and actually I did plan to use it, but only in the roof to hold it in place. For the walls, I spray foamed those in and they are every bit as airtight as they could be. I didn't use it in the roof in the end (for various reasons that I am sure I will expand on by the time I get to that chapter  )
> 
> Martin


Really looking forward to seeing more updates. Fantastic work!
Agreed, Robin is a true craftsman honestly makes everything look effortless. Spray foam seems to also be a decent option and probably more cost effective option, I think I might have used the tape on the ceiling just to avoid getting showered in PIR dust from tapping it in  I'm sure this thread will prove extremely useful for anyone undertaking anything similar


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## Molynoox

yes I think the foam is cheaper which is a shame because if they could sell the Gapotape for just a little less I would prefer that - I think your advice to use it on the ceiling is quite wise by the way, that PIR dust is a nightmare when its above you.... maybe next time


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## Cooper

Molynoox said:


> You will notice that I left about 100mm of the frame 'un-boarded' at the front. This is because I planned to sink the door frames down below floor level. This effectively gains me 22mm of building height, sort of (I only have 2500mm to play with under Permitted Development). Little details like that can all add up and make a difference because I planned to have a vented cold roof (with 100mm PIR), and for that I would need 50mm more height than if I just did a 'hybrid' roof for example (no air gap above PIR). So you need to get creative and think about ways to gain that extra height, or more accurately you are trying to control the height build up.


This is probably a really stupid question but where is the 2.5meters measured from? Our garden slopes down and then has a raised portion. Where I built my workshop is right beside the raised bit (About 60cm, I suspect previous owners covered the remains of an air raid shelter) but from the ground it stands on I've exceeded 2.5 by quite a lot. At the time I was under the impression I was permitted a maximum height of the pitch of 3 meters, which I did. A case of ignorance is bliss. Fortunately the neighbours never said anything.


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## Molynoox

It is measured from the highest point of the land adjacent to the building, this means that some parts of the building could be much higher than 2.5m from ground level if your slope is quite severe. Mine is 2.45m above the ground at one end and about 2.75m at the other end, which is acceptable according to the guidelines.
The permitted development guidelines are reasonably clear for this (but there are some grey areas), here is an extract from the chapter on class'E':






I can help you find the full document if you want it.

Your maximum permitted height depends on how close it is to the boundary and the design of it (flat or dual-pitched roof) - as you can see from the extract above. Hope that helps.

Martin


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## Molynoox

*Jun 2021 - Walls*

Quite early on in my planning I came to the conclusion that walls were an essential feature, I've not seen any garden rooms without them so who am I to buck the trend  
Success factors for the walls as follows:

studs spaced to accommodate sheet goods without unnecessary cutting / waste (400 centres for me)
plumb, flat, level
Centres
400, 450 or 600 - those are the main options. I chose 400mm because its the strongest, and because it is compatible with metric boards either 1200 or 2400. You could use an imperial spacing also if you were using imperial boards, this would be expressed in inches for example 16 inch or 24 inch. I have already talked about metric versus imperial so I won't open the box again. OK, just a little bit... Just to make life fun for us all, plasterboard typically comes in metric sizes and OSB typically comes in imperial sizes. Those constraints represent a perfect combination for screwing up all our careful planning. I've already mentioned my plan in this regard earlier, but I will recap it briefly below:

metric sized sheet goods
400mm centres spacing for studs and roof joists
metric plasterboard on inside
metric OSB on outside
if you are happy with 11mm OSB then you can get it in metric, yay. In the end I bought cement boards for the back wall and two side walls (in metric, 2400 x 1200), and I used the 11mm OSB boards for the front wall.

Plumb
Regarding the 'plumb' success factor this is super critical, particularly for studs that accommodate the sheet 'joins'. The reason being that each sheet you fasten to the studs (ply, plasterboard, cement board) will share a stud which is probably about 47mm thick. This gives you about 23mm for each sheet to fix to. If your stud is not plumb then you are going to create huge issues for yourself because sheet goods are famously 90 degrees square, and if your studs are not plumb then they are not square to the floor and hence won't be compatible with the sheet edges (which are very square). You end up with a taper instead of an even strip:

_10mm spacing error results in a tapered target to fix to_





I didn't fully appreciate sensitivity of this factor when I was building the walls, but realised it later once I was attaching sheet goods to them. Fortunately I am quite obsessive about details, often unnecessarily so, and hence spent some time getting the walls perfect, so I ended up doing a pretty good job of it as luck would have it.

Note: in reality you are not building the studs 'plumb', because you will most likely build the walls flat on the floor and then lift the wall up into position. You are in fact building the studs accurately and equally spaced top and bottom (where they attach at top plate and bottom plate), and then you can make the entire wall plumb once its upright. If your spacing of the studs is accurate top and bottom this will make each individual stud plumb and square once the whole wall is square.
Note: if you are just 10mm out on the stud spacing then you end up with only 13mm to fix to and that would also force you to screw into the sheet edge which is a weak point, particularly for plasterboard. Disengage lecture mode.

Marking
You can either mark the centres or the edges of the studs. You would also probably want to mark multiple studs at the same time to speed things up (might also help with accuracy)

*Centres*
It is easier to mark the centres, because you can simply hook the tape on the end of the bottom plate, and then mark every 400mm using a tape measure. The only issue with this is you have to then judge where the centre of the stud is when lining it up with your mark. It's not exactly difficult but it can introduce small errors.
*Edges*
It is arguably clearer and more accurate if you mark an edge, because lining up the edge of a stud with a pencil mark is less ambiguous and requires almost no judgement. But to do this you need to use a tiny bit more brainpower because you are not marking 'round' numbers. You will still be marking every 400mm, but with an offset of half a stud width which is about 23.5mm. 400mm minus half a stud width = 376mm, so you would be marking at 376mm, 776mm, 1177mm.... Instead of 400, 800, 1200mm.

Here is a diagram to explain because the above is totally unclear, even to me:

_Marking centres_




_Marking edges_





If you mark edges then you may want to also add an 'X' mark or something - this stops you accidentally fixing the stud to the wrong side of the line. Obviously I've never done that ;-)

My method
I was marking the centres of the studs, but then as a second operation I was also going around with a little jig I made to mark both edges of the stud. This took a little bit more time, but it meant that I had error proofed things a bit. I dont have a picture of this so here is an artists rendition:

_Yes its just an offcut with the centre marked in sharpie but I'm calling it a jig_





Alternative methods if marking 'edges

*23.5mm spacer*
I suppose you could cut a bit of 4 x 2 in half to give you a 23.5mm spacer and hook the tape over that before hooking it over the edge of the bottom plate, I've never seen anybody do that however so it's probably a terrible idea :-D You would probably have to clamp it in place which means extra faffing, there is probably a reason that nobody does this. Artists rendition below (note the use of an 'X' so you know which side of the line to fix the stud):





*Story Stick*
You could make a marking stick - or 'story stick' (for example a length of batten) with all the stud placements marked on it - those measurements could easily be transferred to your bottom plate . The only issue I could predict with this would be ensuring it doesn't move once lined up with the edge of the bottom plate - with a tape measure you can keep pulling it tight as you are marking out to check its still aligned perfectly, but with a stick, you never really know if its still lined up at the other end  I guess you could put a lip on the end of the story stick, that would help with error proofing and would also speed things up. Sketch





Nail gun or erm, hammer
I used a nail gun, a green Hikoki (I just hear hokey cokey in my head). I spent a little time trying to decide about this, its £500 for a nail gun and I couldn't figure out if it saved enough time to justify it. Because I was on the fence, it was something quite small that swung the decision for me.... I realised that it isn't just a time saver, its also a functional improvement, its essentially a one handed hammer + nail. This means you can hold a workpiece with one hand and nail with the other - you cant do that with a hammer (making the assumption you have just the two arms). I have no regrets investing, it took me about 30 minutes to build each wall section, which is much quicker than if I had done it manually, but I really like the one handed operation, I can line up the stud with the top / bottom plate and press a button and its fixed, in exactly the place I wanted it.
I feel that gas nail guns are a bit outdated now but they still have their followers. With gas it can be problematic in cold weather, and more importantly for me, you have to keep buying gas - this just seems archaic to me. They are a bit lighter however. Anyway, as far as I know there are only two real options for first fix if you want to avoid gas - Hikoki and Milwaukee, these both work on just a regular cordless battery, and in my experience with the hokey cokey it works flawlessly. Not a single issue in 2850 nails (I have 150 left in the box). Air is the other option I suppose, but then you need a bulky, noisy compressor - way too much faff for me.

Building the walls
Very straight forward, lay all the timber down on the floor, mark out where the studs go, line them up, nail them all in place, stand the wall up. I used either 2 or 3 nails in each stud, depending on how I was feeling, sometimes I was in a 2 nail mood and other times I was in a 3 nail mood. Absolutely no science behind this one at all, I figured that the nails aren't really doing all that much anyway for the walls. (studs are in compression vertically).
Once the wall is upright, use a spirit level to get it plumb in both directions (left/right and front/back) and then fasten diagonal braces in place to keep it fixed in both axes.





Alternative construction method
At this stage, you have to make a decision about how strong you are and how heavy a wall you think you can lift, bearing in mind the embarrassment / annoyance if you go too big and cant lift it :-D Basically, you get more material efficiency and more time efficiency by building either wider walls on the ground, or more complete / complex walls on the ground.

*Wide +*
If you build them wider then you need less wall sections and less joins and that means one less timber stud per join (and a few less nails / effort too). If you are joining subframes together you also need to think about the spacing as that will throw out your 400mm centres if you dont plan ahead and think about what you are doing - not exactly complex but its an extra thing (or 47mm) to think about, and an extra thing to go wrong.

_Wide versus non wide walls_





*Complex +*
If you build them more complex its quicker because doing things flat is easier than doing things upright. This is the reason why we eat our dinners off tables, and not walls :-D What I mean by complex is adding more stages / materials. For example:

OSB sheathing
battens for the cladding
house wrap / vapour barriers.

These can all be attached on the ground when wall is flat. House wrap is a great example... if you think about how easy that is to attach to a wall which is flat on the ground, just roll it out and staple it, 2 or 3 minutes work. Then think about how you might try and do that in vertical position with a 100m roll that weighs 15g - not as straight forward as you might think and could take a few hours to do the full building on your own. So the more you can do when the wall is flat, the better, but you need to be able to lift it. I was working alone so I defined (guessed) my maximum as a 5m wide wall (just the frame, no sheathing or anything else). But if you have access to some additional muscle power (more people) then you should consider adding as many elements as possible before raising it up into position. This 5m width turned out to be about my maximum, I only just managed to shoulder press it up to vertical. My walls are 5 x 2 thick and spaced at 400mm centres so its quite a bit of wood and I'm glad I didn't try and push it any further, like 5.01m for example.
Note: this is a decision you need to know at material ordering stage (do you buy 5m + 4m lengths to get your 9m building width (2 wall sections) or do you buy 3 x 3m lengths (3 wall sections).

Noggin spacing
Noggins stop the studs or joists twisting over time. To fix the noggins to the studs you have two options:

Place them 'in line' and use toenail fixing method
Stagger or 'offset' the noggins and allow nailing from the sides
I am not a fan of toe-nailing, I use it when I have to but it feels like a bodge, and if you get the angle and placement wrong it can make a bit of a mess. So I decided to use the staggered method so I could shoot nails in from the side at 90 degrees.
In terms of placement of the noggins (and I have not seen anybody else doing this - oh ohh, we know what that normally means don't we) but... I decided that if you are staggering the noggin placement then you may as well do it with a useful placement. What made sense to me was to have at least one 1200mm aperture (I can't have two because my walls are only 2.1m tall). So you will see from the pictures my really weird looking noggin spacing - maybe it will catch on.... :-D




Anyway, future self has informed me that this spacing has turned out to be a bit of a masterstroke because it's one less PIR cut to make per stud spacing (uncut PIR is 1200mm wide) which means less dust in your eyes and mouth, and also less waste, which = more beer money.

Note: I know that the noggin would logically go in the centre of the stud, and mine are offset, but actually not by that much, only about 200mm, so I do think this is robust enough, certainly once you factor in the PIR + spray foam mega stiffness combo, oh right that's in the future....

opps, I've hit my 10 picture maximum again, I will put the pictures in the next post.

Martin


----------



## Molynoox

*June 2021 - Walls (part duh)*

Can you spot the mistake?
*


*
I think this wall was the heaviest one and there was much grunting. Oh yeah, the mistake was the fact that I built this as if I was looking at the wall, you know, window at the top etc. But of course when you rotate it upwards into position everything is upside down  but don't worry, that isn't the daftest thing I did.

Waterproofing attempt 3
Yep, having a wall gave birth to another waterpoofing attempt. Result = dry on the right, wet on the left. Not bad.





_Wet ground = home made path_












_Running a string line to ensure the wall is straight_




_Header for french door and windows in_





_The PIR tower of shame..._




_- that insulation has been sitting there for months because I ordered it at the very start with all the other materials, one of my first mistakes but one of many._

Well I think that is it for the walls. Notice that all the noggins are not in at this stage, and the cripples / supports under the windows are also missing. I will cover the bi-fold header in a separate post because that is a bit more interesting... well it is to me anyway 

Martin


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## Inspector

When I got out of high school my first job was as a framers helper. When laying out the top and bottom plates for the studs etc we put a few nails in them (not all the way so we could pull them quickly) and marked them together. The framing squares that have been in use here forever have the shorter tongue an inch and a half wide, the thickness of the studs. Lets you mark the stud spacing without as much thinking or the need for a jig.  We also installed all the headers and sheathing while the wall was on the flat. When a wall was a little to heavy for the three of us to lift the call would go out to other framers nearby or other trades to help with the lift. Multiple walls would be ready for the raising. Now they are using jacks or boom forklifts.

I'm enjoying your progress.

Pete


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## Molynoox

Haha that's cool about the framing squares!  Like the first time you realise a hand saw has a 90 and 45 degree guide built into the handle....


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## Inspector

Yup and the 1 1/2" leg is 16" long and the 2" wide leg is 24" long. Hey that the standard stud spacing!  There are a lot of Duh moments you discover when you are a do it yourselfer. Usually when you are just about done.

Pete


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## Molynoox

Haha that's even funnier, I have one of those as well, never realised. I just use it like a big square.


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## Molynoox

*Jul 2021 - Bi-fold Beam*

You will see from one of my earlier posts that I elected to use a flitch beam above the larger of my doors, which happens to be a bi-fold. It is a 2.4m wide opening and the beam is intended to give the door a stress free life and in return will reward me with a nice smooth trouble free operation throughout it's life. In theory.

Components
Here is the flitch beam in puzzle mode:




A flitch beam consists of 3 main structural components (sometimes 5, but mine had 3): a flitch plate and two timbers (which sandwich the flitch plate). Together they become a flitch beam. The whole assembly is bolted together. The flitch plate is made to order so you have to get your measurements right. It has a weather resistant coating on it, but its not exposed so it doesn't really matter. It took me a while to find a place that could make one for me, and the delivery costs were about the same as the cost of the flitch plate itself, so I drove over there and picked it up. I think it was 2.9m long to give an overhang on each side, although I would probably make the overhang bigger next time. I took care to select the straightest timbers I could find from my big pile too.

Drilling and bolting
I had to drill holes in the timbers that exactly mated up with the ones in the flitch plate (so that I could get bolts all the way through) - I did that in the most obvious way by placing the flitch plate on top of the timbers and then drilling down through them (with auger bits). I had to also create rebates for the bolt heads on one side and the nuts on the other using a forstner bit so that they don't protrude. Is rebate the right word for circular recess like that? Is recess the right word for a cyclindrical cavity like that? Is cavity.... never mind.
Tip: drill the forstner holes first, then follow up with the through hole, otherwise the forstner bit centre will be spinning in air and it wont centre itself. Actually, I think I screwed up when I did it, and had to make a jig (yes another of my famous super complex jigs) which enabled me to drill the forstner hole *after *I already had a through hole. Its basically a hole in a piece of wood that guides the bit. But its still a jig.

Once all the holes were made in the timbers, I then mixed up all the parts so that I didn't know the correct orientation of each part - that gave me a fun puzzle to work on in the rain. Next time I would definitely label the parts with a left, right, front and back, because as it stands there were 4 ways for each timber to be oriented, and I tried all 4 before finding the right one. The holes were a tolerance fit so everything had to be perfectly aligned for the bolts to go through. I did a test fit of the bolts and then disassembled it, but only after labeling all the parts. Because the flitch plate was pretty heavy, the plan was to assemble it in position, and not on the ground.

Lifting the beam into position
As per usual, I am too stubborn to ask for help, and ended up lifting the parts into position on my own. Turns out the flitch plate is pretty heavy, certainly enough to summon 'grunting man' and it was nearly heavy enough for 'swearing man'. Once I had the holes in all three pieces lined up I pushed the bolts through and tightened them up with my impact driver and socket. Probably used some washers too. I definitely used a big hammer. Once the beam was assembled and in the right place I fired about 20 construction screws into it from underneath to tie it to the building structure. Then I did the obligatory 'jump and hang' manoeuvre to check it for strength, the equivalent of kicking the tyres. Not in any way empirical or meaningful but it made me feel good so I don't care.

Wall thickness and spacers
the two timbers plus flitch plate added up to a thickness which was less than the thickness of my wall (which is 5 x 2). This means I had to use a spacer to get the beam flush with the rest of the internal wall. I think I was about 20mm short so ended up using two bits of OSB cut to size or something like that. I cant actually remember. I had to do the same above the french doors too, except that was a different thickness because I used two timbers there, *without *a flitch beam.

Pictures
_Partially assembled_




_Fully assembled (a roof has mysteriously appeared also, which is weird)_




_View from the front (roof has gone again)_




_Screws used to fix beam to building_




_Oh look, labelled parts! (and the roof is back)_





Time to put the roof on.....
Martin


----------



## Inspector

" Is rebate the right word for circular recess like that? Is recess the right word for a cyclindrical cavity like that? Is cavity.... never mind." I call them counterbores. If just a touch deep or providing a perpendicular to hole for an angled surface I call them spot faces. At least that what the aircraft world calls them.

The "spot the mistake in post 53". Is the window at floor level or is that a cat door? I ask because when one builds a wall the sole plate is at the edge of the floor to stand it up.

I guess with working alone putting construction adhesive on both sides of the flitch plate wasn't in the cards eh?

Pete


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## Molynoox

What can I say Pete, the lengths I go to just to make a little quiz for you, I deliberately built it upside down of course. After all... nobody would make a mistake like that.

Liking the hole lingo, I have entered counterbore into my memory banks as the chosen one.

Is construction adhesive a real thing?

Martin


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## Inspector

Construction adhesive comes in caulking gun tubes, either a little under a foot long and an inch and a half in diameter or bigger ones almost two feet long and about two and a half inches in diameter. It is a form of polyurethane but doesn't foam like Gorilla Glue. It gets used a lot on floor joists, studs or rafters just before dropping a sheet of plywood/OSB on it followed by nails or screws. Makes the structure a lot stronger but if you don't have your act together it is messy snot.

Pete


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## Molynoox

*Jul 2021 - Roof (structure)*

This stage is pretty quick and straight forward, it's just a case of cutting the rafters / roof joists to length, and then balancing them on top of the frame before fixing in place with truss clips (front and back).

Overhang
My design has a 400mm overhang at the front and 100mm at sides and back, which makes the rafter length 3,700mm + 100mm + 400mm. This makes it 4,200mm which is the exact length of timber I ordered. I measured each timber and trimmed off a nominal amount from each to ensure they were all exactly the same. So I probably ended up with 4,190mm or something, and a 390mm overhang at the front. I think this looks about the right size but you could easily go to 600mm or even 800mm and it still look balanced I reckon. That could depend on your overall building depth though, to get the proportions right, but it's all personal preference.






Ladder
One detail which wasn't 100% straight forward was the overhang at the sides. To get this to work I needed a 'ladder' (as I believe it is called). One mistake I made here was to use way too many structural / sideways supports (these are the bits that looks like noggins in the pics), I probably could have used half the amount of 'noggins'. I used 400mm spacing, to mirror my stud spacing, but with only 100mm overhang, and with it not really supporting that much weight, this 400mm spacing feels like total overkill.

_you can just about see the 'ladder' in this picture_




Joins
I dont know what you would call the component in question here, it is the piece of wood that runs along the front (and back) of the overhang to connect all the roof joists together. Because my building is 9m long, I need to use multiple timbers along the front and back (because you can't buy 9m long timbers, or you maybe can, but I don't want to handle that length!).
There are two ways to handle this, either make sub frames (like I explained with the walls) or try and do it in a single structure. With the single structure option the joining 'front' timbers end up sharing a joist - this makes fixing it a little more of a precision operation.
If you use sub frames then each joining front timber has its own joist, the disadvantage being that you use an extra timber, which isn't really needed from a structural standpoint. For 6 x 2 timbers @ 4.2 metres and with current timber prices it seemed like throwing money down the drain to use the sub frame option. I nailed through at an angle using the nail gun and the fixing felt strong enough
Here are pictures to explain because the above isn't clear:

_Option A - sub frames_




_Option B - single structure_




Truss clips
I have seen a lot of people using joist hangers to fasten the roof joists in place at the front and the back. I am not sure why this is, because truss clips seem to be designed for this purpose, and are also a little easier to fix in place. Anyway, that's what I did. Hopefully somebody can explain to me why this is not right....

_detail showing truss clips and also the joist sharing from option B_




Mistakes
The only thing I can think of which I would change for next time would be to run a string line down the front of the overhang to ensure that all the timbers were lined up perfectly in a perfectly straight line. The method I used was fine in theory but in reality it could introduce small errors. What I did was to assume the front wall of the building was perfectly flat / straight and then simply use a consistent overhang distance of 400mm for all the joists.
I think it would be better to run a string line from the joist at the far right, all the way to the joist at the far left, and then set the remaining 30 or so roof timbers to the string line. This way you know they are perfectly aligned at the front, instead of assuming they are, and potentially mirroring any imperfections in the wall straightness into the overhang.

More pics






















Martin


----------



## Molynoox

*Jul 2021 - Roof (boards and EPDM)*

Super fast and simple stage. Simply push the boards together and then glue and screw them.

Details
I used floor board screws and I used the 'normal' method of cutting the board for the end of the run, and then using the offcut to start the next run. Same technique as used for the flooring.
I took care to push the boards tight together (I used a piece of wood and large hammer), and also ensured that I got the boards running perfectly in line with the back edge of the roof. I think I did a dry run by laying down all the boards for the first run (along the back edge) to check it all laid perfectly in line before I went anywhere near the glue and screws.
As with the floor, I didn't bother trying to align the board joints with the joists, the boards are really thick and have a tongue and groove and its plenty strong when glued together.

EPDM
I ordered some EPDM and trims from Firestone. I did a bit of looking around and this company seemed to offer the nicest trims, and also the EPDM seems to be a slighter darker 'black' colour rather than the sort of dusty grey you get sometimes. I preferred the look of this.
Anyway, the big challenge was getting it onto the roof so that I could roll it out and finally make the structure (mostly) waterproof. The EPDM weighed 80kg which is quite significant when you need to lift it 2.5m. I guess the 'normal' way to do this was to use two people and two sets of ladders and walk it up in tandem. I didn't have two ladders or two people available, therefore I opted to do it on my own. I won't go into too much detail, but suffice to say this was right on my limit. I hoisted it up onto my shoulder and walked it up the ladder. I needed a proper sit down afterwards.
I rolled it out and manoeuvred it into position so it covered the whole roof. There is 150mm overlap on all sides which is what Firestone recommends when ordering the EPDM. I clamped it in place with 8 large Irwin spring clamps, which will be in place for quite some time because I won't glue it in place for quite a few weeks.

Mistakes
I didn't really think about the glue dripping down through the joints and onto anything below. Not a problem for the floor, because it scraped off really easily once it was dry. But my wife's egg chair thing was sat under the overhang and hence that got covered in the PU glue and so did a few other things. No too smart...

Pictures
_Stage 1 of me ruining my expensive mountain bike armour by crawling around in PU glue. Also did a bit of roofing._








_looking like a building now (ish) - you just need to squint a bit, and use your imagination_





First time standing 'inside' felt great













_Egg chair after clean up - it's like it never happened....._










Martin


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## Molynoox

*Jul 2021 - Front wall sheathing*

Pretty simple stuff here, just screw the OSB in place. The only interesting part was cutting out the apertures, and how best to do it, or not do it...

State of play before I started work...




...looking quite nice in the sun. Also notice the PIR tower of shame is now hiding inside the structure. It was nice to finally see the building in full view.

Method 1 - fix and cut
Screw OSB in place, cut out aperture 'in situ'.

Method 2 - mark and cut
Temporarily screw OSB in place, mark the apertures in pencil, remove OSB and cut out hole, fasten OSB back in place.

Method 3 - measure and throw
Measure the aperture, transfer measurement to OSB, cut out, fasten in place, realise measured hole is not right size, throw OSB in bin.

So I found that cutting things 'in situ' with method 1 was a little problematic and therefore method 2 was my favourite from those tried. I used a circular saw to cut the hole, but you could use a jigsaw, or even just normal manual saw I suppose. I made sure to clamp the board firmly in place before marking it.

For method 1, I tried a few different ways to cut the hole with the OSB fixed in place. Router, circular saw, jigsaw. None of these felt very safe or accurate. The router option seemed to be going quite well as the roller bearing sat flush with the timber frame thus ensuring that the final dimension was exactly perfect. However, at one point (the point at which I stopped) I had a big nope moment as the router quite voilently backfired and shut itself off. I'm not entirely sure what I did to cause that to happen, but I took it as a warning to 'not do that'.

Mistakes
Another repeating theme, which starts from this point onwards, but continues ALL the way through the build, is forgetting to mark the positions of the studs before its too late. It's no trivial matter to measure and mark those positions once the boards are in place and covering the studs up. Frustratingly, it is incredibly simple and quick to do if you think ahead and mark them before fixing the board in place.

Pictures




_engage movie lighting mode_




_Evidence of router incident_






















Martin


----------



## Molynoox

*Jul 2021 - Wall insulation*

Finally I got to use the PIR.
The key thing at this stage was having an efficient workflow, the 4 key factors for me were as follows:

Measuring
Marking
Cutting
Moving material around
Measuring and marking
Even though I had a fairly consistent aperture (1200mm x 353mm in theory) I still measured every one before cutting the PIR. There were some small variations of a few mm here and there, and many of the apertures were non standard shapes. Also, measuring it became super quick so I didn't mind doing it. The method that worked for me was to install one PIR 'block', then at the (almost) same time measure the next one (which was always right next to it) and rather than take a note of the measurement I would just lock the tape measure at the right size and then walk over to the PIR sheet and use the tape as a pre-configured scribe, and use it to score the cut line on the PIR with the tab on the end of the tape. Once you get into the zone this whole measuring and marking operation takes just a few seconds.

_Alternative method_
Sometimes, you might have a slight 'angle' to deal with, in theory you shouldn't do, but for whatever reason sometimes the hole for the PIR was maybe 5mm different from top to bottom. This is enough to cause issues getting the PIR block into position. I did want it friction fitted so it stayed in place, but if its just a few mm too big then it creates a bit of a PIR dust / faff nightmare to shave off that few mm and get it to fit.
Anyway, the way I dealt with the angle was to measure top and bottom and just remember the difference between the two (if any). Then, when I score the cut line on the PIR using the tape I would just slowly pull the tape over that extra few mm as I scribe down the sheet. This doesn't sound like it would work, but it did - in fact it is surprisingly easy to do and get it accurate. Does that make sense? Probably not. Moving on...

Cutting
The key was to setup two tables to facilitate cuts on the end of the boards and also through the middle of the board. If I had an offcut on the end of a sheet that was smaller than my standard 353mm I would put it to one side as it can almost always be used later. A tip here is to first (before setting the offcut aside) measure it and mark the width with sharpie so its clearly visible from head height. This way, when you have a pile of 5 or 10 offcuts lying around, its very fast to find the one most suitable, rather than measure them all every 5 minutes over and over again. Not that that ever happened.... ;-)
I used the old rusty hand saw technique for cutting the PIR as this was established early on (while doing the floor) as the most efficient method for me. Note however, that I didn't trust past self and hence performed the PIR cutting experiments again, only to get the same outcome that the manual saw was the best method.

Moving material
The other key factor was to have the PIR pile, right next to the cutting table. The ultimate setup would probably be table in the middle of the building, with PIR pile to the right or left. This minimises the #metres walked because the common operation is moving between cutting table and the building stud work / apertures. By the way I was walking 5 or 6 miles per day doing this stuff according to my Garmin, so that's probably 2 or 3 hours of walking per day. I can get a bit obsessed with efficiency sometimes so sorry for that - I am sure sometimes I make myself inefficient because I spend too long trying to optimise processes. Slightly ironic perhaps.

Aperture size
I've mentioned it one or two million times already but setting the height of the apertures at 1200mm when I did the wall studwork was a winner because I didn't have to do any cuts of the PIR in the width dimension, which means no material waste and also no time wasted making cuts that I dont need to. Hurrah

Wedges
I found that having a few little slivers of PIR floating around was handy if I needed to wedge the PIR bocks in place to keep it in position. Sometimes I would get the measuring and marking slightly off which means it doesn't friction fit and wont hold itself in place. So using the little wedges was a quick and easy way to fix that problem

Duration
Once I had figured things out I was able to install it quite quickly. I think I managed to do all the walls in 2 days (it might have been 3, cant remember, but then that includes some inefficiency at the start when I was figuring out the best workflow).

Pictures

Cutting tables








Note: its very important to have a few random object lying around that don't need to be there such as step ladders, tripods, bicycles and scooters, otherwise you have nothing to trip over. Imagine how boring that would be!


















_PIR jigsaw puzzle_




_Room of mirrors - the PIR makes it super bright inside_


----------



## Molynoox

*Jul 2021 - Cement Board and House Wrap*

As I mentioned previously, I needed to use cement board, not OSB, because my building is within 1 metre of the perimeter of my garden. This was required to make it exempt from building regs because the building needs to be made from 'substantially non combustible materials'. Planning officers local to me were OK with this.

The downside to using this material is the cost and weight. The boards weigh 45kg each so not very easy to hulk around on your own. I found that the sheet goods carrier I bought was an essential piece of kit for picking up the boards and carrying them around the back of the building.

Cutting
I cut the boards 'in situ' from the pile on the floor inside the building. I made the cuts using a cheap 16 tooth blade (this was advised from the internet) and a Makita 36v twin battery circular saw. I don't know if this monster of a saw was needed or not, but my Makita single battery jobby was struggling cutting lengths of timber when it was wet and figured that a more powerful saw would be good for cutting the cement board too. That was my justification to myself. That saw and blade combo was a winner as it was going through the boards like butter, I managed to cut all 17 boards without any issues with blade sharpness, cuts were fast and clean. It did create a lot of dust though.
Oh yeah, I also used a home made guide rail which I had made out of OSB, which worked absolutely brilliantly. You lose 12mm of cutting depth I suppose, but that is rarely a problem. It meant that I didn't really need to see what I was doing once the rail was lined up - you just whiz the saw along the guide and the cut comes out perfect.

Locating
Once the boards were cut I carried them to where they needed to be fixed at rear and sides of building, using the sheet goods carrier thing that I bought from amazon. Before doing this however, I first put support blocks in place, which were approximately perfect (oxymoron?) height for the boards to rest on. Once I had placed the boards down on top of the blocks I would fine tune the exact height using 5mm ply spacers which I had knocked up. Once the board was in the perfect position I screwed it in place through the studs.
Note that (again) I rarely remembered to mark the position of the studs before fixing the board in place at either end. So ended up measuring and marking the studs in the middle of the boards. This is becoming my go-to method for eroding all my efficiency.

Fixing
To fasten these boards I used the special Timco screws which the board manufacturer (Fermacell) recommends. These had quite small heads, and were available in a pozi drive only (I like the torx ones much more, because they work). I recommend using gloves for this task as the screws have a habit of inserting little metal burrs into your thumb and finger after you have put in 1000 of them. Same problem with plasterboard screws. So if you are not going for the glove option, then factor in an extra 30 minutes at the end of the day to remove all the little metal splinters from your fingers.

Apertures
Actually, I only had one, the bathroom window, but I had to deal with that somehow. I decided to fix the board in place and go for the cutting 'in situ' option, despite that being previously established as a bad idea when using OSB on the front wall. I used a multi tool this time, and that worked pretty well. It was a bit noisy, and a bit dusty, but I got the job done with quite neat cuts. I think I tried using a multi tool when cutting the OSB on the front walls too, but although very accurate and safe, it was too slow. Or I am too impatient.

House wrap
This would be waaaaay easier if you were able to do it when the walls were laid flat, but that wasn't an option for me. Anyway, it just took some perseverance. I stapled it in place using a cheap Titan electric nailer / stapler that I had lying around - that seemed to work ok, but the cable is very annoying. Probably just a manual hand held stapler would be better. I didn't have one of those 'at this stage'. As regards tool ownership, it doesn't seem to be a case of 'if', but more a case of 'when' you have it...

Dupont flexwrap
I honestly don't think I needed to use this product, and it was quite expensive. It forms a waterproof layer around the edges of the frame for windows and doors. I consulted with the window/door fitters when they arrived and they say its not necessary, and in fact have never seen it used before. I suspect it is more applicable for an older design of window or building, but I'm open to any feedback from anybody with thoughts on that one.

Pictures

_Pile of cement board - just 765kg_












_wrapping up my wife's Christmas present (little did she know it would be for NEXT christmas... )_




_apertures cut_








_Flexwrap stuff and seam tape_









Martin


----------



## Molynoox

*Aug 2021 - Internal Walls and TV and Office Planning*

Time to put up the wall between the office and the workshop. Oh yeah, and create a bathroom also. Quite a lot of learning in this stage

Partition Wall
The partition wall was very straight forward. First create a top and bottom plate and fix it into position. Then just measure the height of the required studs, and cut each stud and nail it in place, ensuring it is plumb. I used 400mm centres, as with the external walls, even though it isn't load bearing and probably doesn't need to be that strong. I wanted to keep it consistent to make finding studs easier, and also thought the added strength would be good with the bathroom door slamming shut all the time. I did use 4 x 2 though, instead of the 5 x 2 which I used for the walls.

Doors
This was the bit I was quite clueless about, I didn't know that door linings existed until I was building the bathroom walls and did some research into how best to do a door opening. I decided to use a 'standard' 30 inch door, or 762mm. This means that sourcing the door lining and door is fairly straight forward. So I went out and bought a door lining and then when I got back home I tried to figure out how deep I needed it to be, and also how tall I needed it to be. The width is fixed at 762, or probably a bit more I guess, I'm not sure how much more as I don't remember measuring it, although I'm sure I will have done just to avoid the disaster scenario.

HEIGHT
So, standard door height is 1981mm (78 inches or 6.5 feet) so I had to think about my floor build up in order to calculate the height that the door liner needed to be cut to. My floor was probably going to be 5mm underlay + 12mm laminate. So I added those together to get 17mm (so far so good) and then added a random fudge factor to give me some door clearance underneath. I probably looked this up, and I can't remember the number I got, but maybe 10mm? Anyway, I added the 27mm or whatever to the door height, and then cut the liner to what I assume was about 2008mm, but I honestly don't remember.
When I come to fit the door we will see if my calculations were sensible or not.

DEPTH
Basically set the depth of the liner to your wall thickness, plus a bit for plastering. When they plaster the walls, they need a small lip to plaster up to and give you a neat '90 degree' finish. I went for 3mm each side which meant the liner was 6mm deeper than the thickness of the wall. So liner was probably 98mm if my timber is 92mm, but I honestly can't remember. I ripped this down with the circular saw and the guide fence thing that projects from the side of the saw. I think I ended up taking off about 5 or 10mm.

Tip
When fitting the door liner, I strongly recommend connecting together the bottom of the two verticals with a piece of timber - this would keep it fixed at exactly the 762 or whatever it is supposed to be. The top is restrained by some rebates that set the verticals at the correct width, but the bottom isn't. If these are out by even 1 or 2mm, it will show as a taper against your door edge when its fitted. Although I suppose you could plane the door down. I suspect I will need to plane my door down a bit, as I notice one or two mm difference from top to bottom in my frame / liner, even though I fixed the bottom like I just described. So maybe don't listen to me...

Build it vertical
Note that when it comes to putting up internal walls, you cannot build them flat, because you won't be able to rotate the wall up into position without fouling the ceiling. This makes it a bit trickier to build the door opening stuff.

_from workshop side_




_from office side_




_without door liner_




_with door liner (and children)_




Mistakes
If I was doing this again, I would probably build the wall with enough space for the liner PLUS 10mm. Then when I installed the liner I would install it into the opening using spacers / wedges to get it perfectly plumb and with consistent 762 width from top to bottom (or whatever that width is!). I am sure if you look it up on youtube they will probably do it something like that and not the way I did it with the opening the exact same size to accept the liner. I should go and look that up now.

Desk planning
At this point we had the electrician round to do first fix and I had to do some impromptu planning / decision making for the lighting placement. It was only of importance for the area above the desk, because my wife is a math's tutor and does a lot of stuff with whiteboards and cameras over zoom. For this reason, the lighting is quite tricky to get right - not enough light and you can't see what's being written, but too much or more importantly badly positioned light and you get glare (specular highlights) from the light bouncing back into the camera and/or also shadows cast by your hand as you write. So with shadows and specular highlights to contend with the only option (in my mind) was to setup a mock desk, and get the laptop fired up in a virtual zoom meeting and play with the light placement and see which position worked best.

The conclusion from this research was that all lighting positions are terrible and therefore she will need to work in complete darkness. Seriously though, it was very challenging to find a good lighting solution, and what we settled on was a large 1200mm x 300mm light panel, situated slightly behind the chair position. Oh yeah, and that will also be on a dimmer circuit so it can be controlled quite accurately. The backup option if all this planning doesn't work out is to use the 'desk lamp' setup which she is currently using (this works ok but it isn't optimised).

_desk planning_




I also did some 'very important' TV planning at this stage to try and figure out what size to buy, and also what type of speaker setup to go for (in wall, on wall, bookshelf, tower, soundbar etc.). That is probably getting a little off topic for this audience however, so perhaps I won't go into the details for that unless somebody is interested in which case I am happy to cover it. Not that I know much about that stuff - just enough to make decisions.

_TV planning_









Martin


----------



## Molynoox

*Aug 2021 - Doors and windows - part 1*

Oops, I missed a stage!
The doors and windows were fitted before the partition wall stuff. Well, sort of. There was a bit of a screw up on the part of the supplier (I won't mention them):

The doors arrived with a low profile threshold, not the weathered / rebated threshold which I ordered.
The glass for the doors and windows did not have the internal blinds
The glass for the doors did not fit into the frames (but they would have fitted a rebated threshold door)
So after a few emails and phone calls we had a plan. Unfortunately it would take them 8 weeks to create the new glass. I settled on keeping the low profile threshold frame with a negotiated discount. I was actually quite happy with this as the discount was nice to have, and I always wanted to low profile threshold anyway, but didn't like the risk. Once I could actually see the product, I was able to make a better decision and I decided that the low profile threshold was plenty weatherproof for my application.

Product details
The product I ordered was a 'Cortizo' with aluminium frames, double glazed, in anthracite colour - I believe the panels / frames they use are Dutemann ones, which are very well regarded ones. The product is very similar to the Express bi-folds ones from what I can figure out, but it's a bit cheaper. Shuco and Origin are the other two big names with small sightlines etc that seem to be getting used everywhere under different brand names / companies. I am convinced they are all pretty similar but you pay for the marketing and customer care with some of the more expensive companies (which may well be worth paying for)

This was supposed to be a bit of a high point for us as getting the doors and windows fitted felt like a bit of a milestone, so it wasn't quite the event we had hoped for with all the problems that were uncovered on the day. However, the supplier was happy to sort things out so there was no animosity from either side, it was just a bit disappointing for us.

Pictures

_Notice the special non-reflective glass (not) in the doors... _





















Martin


----------



## Inspector

Nice doors. I couldn't use them though. Blows here too much and the wind would rip them off. Have to be careful opening cars doors for the same reason too. 

I've built partition walls inside on the floor and tipped them up. You make them a touch short and put shims or wedges on the top where you nail them to the joists or rafters.  

Keep the pictures and commentary coming.

Pete


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## AJB Temple

First rate thread. Can't imagine how I missed this. Among the best written WIPs I have seen.


----------



## Molynoox

Inspector said:


> Nice doors. I couldn't use them though. Blows here too much and the wind would rip them off. Have to be careful opening cars doors for the same reason too.
> 
> I've built partition walls inside on the floor and tipped them up. You make them a touch short and put shims or wedges on the top where you nail them to the joists or rafters.
> 
> Keep the pictures and commentary coming.
> 
> Pete



clever stuff!


----------



## Molynoox

AJB Temple said:


> First rate thread. Can't imagine how I missed this. Among the best written WIPs I have seen.


thank you sir.


----------



## robgul

Fantastic - looks like a significant investment.


----------



## Molynoox

robgul said:


> Fantastic - looks like a significant investment.


yes it should be a big change for us a family, gives us all a bit more space, and jazzes up the garden a bit for the summer. I haven't added up the costs yet but I imagine it will add enough value to the house to pay for itself
Martin


----------



## Sheptonphil

How did you manage to get it exempt from building regs? It’s over 30sqm and less than a metre from the boundary and has running water. Any of these could put it in building regs territory, let alone all three.


----------



## Molynoox

Sheptonphil said:


> How did you manage to get it exempt from building regs? It’s over 30sqm and less than a metre from the boundary and has running water. Any of these could put it in building regs territory, let alone all three.



Hi there, here are my answers

1. The exterior dimensions are not relevant for BR and the interior of my building is under 30m2
2. It is within a metre from the boundary but I made it from 'substantially non combustible' materials (Fermacell etc)
3. the building meets all exemption criteria under class 6 (small detached buildings) and does not contain sleeping accommodation - part P still applies but the electrical work is being subcontracted to a qualified electrician.

maybe I missed something, could you point me to the part of the building regs that states that running water means BR? thanks

Martin


----------



## Sheptonphil

Molynoox said:


> Hi there, here are my answers
> 
> 1. The exterior dimensions are not relevant for BR and the interior of my building is under 30m2
> 2. It is within a metre from the boundary but I made it from 'substantially non combustible' materials (Fermacell etc)
> 3. the building meets all exemption criteria under class 6 (small detached buildings) and does not contain sleeping accommodation - part P still applies but the electrical work is being subcontracted to a qualified electrician.
> 
> maybe I missed something, could you point me to the part of the building regs that states that running water means BR? thanks
> 
> Martin


Ok, I assumed your title dimension meant you had more than 30sqm internal. However, even though you have made adjoining parts predominantly non combustible (a condition of building regs for buildings greater than 15sqm and less than 30sqm internal if closer than 1m from boundary), the fact that any part is closer than 1m it is no longer exempt from building regs under section 6 As it is over 15sqm internal.


----------



## Molynoox

Hi Sheptonphil,

my building is falling under item 1 as defined below (this is a screenshot from building regulations), and as far as I understand it you don't have to satisfy all 3 items, it's not that type of a list, otherwise I would also have to be building a nuclear bunker to satisfy item 2  

as an additional hypothetical scenario, if your building is under 15m2 then (according to the definitions below) you could build it close to the boundary (<1m) and still be exempt, and you wouldn't need to think about using non-combustible materials either.

I believe that's what the regulations say, but based on feedback that I received on this forum I was strongly advised that local planning officers should be consulted anyway. I spoke to mine and they were very happy with my designs and gave me confirmation that I am exempt from BR.

Hopefully that has cleared things up but if not please comment so we can clarify, thanks

Martin


----------



## Molynoox

*Aug 2021 - Planning for Pergola and Decking*

I thought it was worth mentioning this 'stage', because even though nothing was achieved in terms of building work, it was a significant event as it enabled decision making for the 'outsidey' bits; the decking, path and the pergola. The pergola was never really in the initial plans but as things progressed my wife discovered that adding a pergola would be an excellent way to complicate the build further. In reality we both decided that a pergola would be a pretty cool addition. We also made the foolish decision to use cedar, despite the fact that this could be the worst possible time to purchase cedar in wood purchasing history.

Design Options
Some of the design options are captured in the below sketches and ultimately the main decision was choosing between having an angled pergola (to match the angled decking) or to have a simple 'straight' pergola. I say simple, it was enough to give me a headache.









Prototype
To help decide which option to go for, I cobbled up a rapid prototype out of sticks and clamps. Although we liked the look of the angled pergola, in the end we decided against it. Honestly can't remember why now but I think needing an extra support post to the left of the bi-folds was a factor as it would end up looking a bit more clunky, whereas the straight / cantilever style design we ended up with has a nice clean look to it. Also, the extra support post could get in the way, not just visually but physically.#








The prototype was really useful for getting a feel for things before making a decision so defo the right call to make one.

Final designs
*Pergola*: straight (not angled like decking), cantilever design
*Decking*: 800mm wide path in front of building and larger diagonal area for lounging around on, eating etc (dark grey in CAD)
*Path*: some sort of stones / tiles running between decking and house (and around the sides a bit) (light grey in CAD)

I will cover the actual build of the pergola in a later post but here is the final design:

























I have ran out of picture allowance in this post so will roll over to the next...


----------



## Molynoox

*Aug 2021 - Planning for Pergola and Decking (continued...)*

Foundations
I have decided to use self install groundscrews to support the posts. Why:

• Fast to install and don't need concrete
• Posts do not need to be buried in ground (which is a rot risk), instead they sit a little above the ground in brackets on top of the screws so the rain water can drain away.




The only issues with groundscrews is they work out a bit more expensive, partially due to the delivery costs which are about £100. Once installed the pergola posts will also serve to support the decking base (screwed through the side) in addition to the adjustable plinths I plan to use for the decking base.

Screen stuff
One the key reasons for the pergola was to enhance privacy to / from neighbours, especially as the garden room is about 250mm off the ground at one end.
Note: There is a restriction under 'permitted development' guidelines about decking (I think they may call it a veranda or balcony or something). I believe the maximum for a raised platform is 300mm, so we are legal, but ultimately we wanted a secluded feel anyway and the regulations weren't the driving force.

The plan was to have some screens along the back of the pergola, made out of trellis type material, or maybe even strips of cedar. The trellis stuff would work well because you can still see through it when viewed 'head on' and hence it doesn't block all the light, but when viewed on an angle it would (theoretically) block the view from the garden room into the neighbours house / garden. I reckon it will give quite a nice secluded vibe to the garden, but even future Martin doesn't know if that's true or not yet.

Here is a design that a friend built, also cedar, and also using the trellis. Note that the trellis is just bog standard B&Q stuff, but it colour matches really well so I will be looking into that when the time comes.





Here are my sketches showing planned placement of trellis








Plants will be encouraged to live on said trellis and hopefully integrate the structure into the garden a little better.

Here are some views showing the effect on eyeline / visibility / privacy stuff:

WITH trellis




WITHOUT trellis





I don't really like the look of the trellis so will play with some other designs at some point but the basic concept is in the right direction I think.

Martin


----------



## robgul

I know what you mean about trellis and off-the-shelf fencing etc - I've just fenced the whole of our garden with horizontal slats about 12mm apart - the timber is just roof batten stapled onto the uprights (with the neighbour's lap fence behind) Very pleased with the effect.


----------



## Molynoox

That looks really good Rob  cool idea.

Looks like you are running a mini restaurant with all those tables; how much for steak and chips?
Martin


----------



## robgul

Molynoox said:


> That looks really good Rob  cool idea.
> 
> Looks like you are running a mini restaurant with all those tables; how much for steak and chips?
> Martin


 - yep, it did look a bit like that with the tables - the patio had only just been laid and we just got all the furniture out.

The fence idea also looks pretty good when it's painted - this is at the front of the house, stained with Cuprinol Garden Shades Ash Black


----------



## flying haggis

If you went with an angled pergola, I would "hang " the end from under the roof overhang instead of having the post in front of the building in the way of the door. Does that make sense?


----------



## Molynoox

robgul said:


> - yep, it did look a bit like that with the tables - the patio had only just been laid and we just got all the furniture out.
> 
> The fence idea also looks pretty good when it's painted - this is at the front of the house, stained with Cuprinol Garden Shades Ash Black
> 
> View attachment 122355



looks brilliant, nice idea, and nicely done too


----------



## Molynoox

flying haggis said:


> If you went with an angled pergola, I would "hang " the end from under the roof overhang instead of having the post in front of the building in the way of the door. Does that make sense?



that's a smart approach, I like it.
the only potential issue is that the height of the pergola spars are then a little constrained by the specifics of the building design but they are at similar heights so probably not a problem

I remembered another deciding factor for straight design too; I believe I was struggling to get Cedar in lengths longer than about 2.5m, so that made it tricky to get the long diagonals sorted. I think needing those lengths pushed me towards more expensive Cedar suppliers and that helped me decide to go 'straight'.
Martin


----------



## clive griffiths

robgul said:


> I know what you mean about trellis and off-the-shelf fencing etc - I've just fenced the whole of our garden with horizontal slats about 12mm apart - the timber is just roof batten stapled onto the uprights (with the neighbour's lap fence behind) Very pleased with the effect.
> 
> View attachment 122352


Hi Rob.
What is the paving you have.

Clive.


----------



## robgul

clive griffiths said:


> Hi Rob.
> What is the paving you have.
> 
> Clive.



It's black sawn limestone in 600 x 900 size - that has been sealed with Stonecare colour enhancer (probably need re-doing every couple of years) The wall cladding is Thermowood fixed on batten attached to a blockwork wall


----------



## Molynoox

*Aug 2021 - Rain Drain and Decking Prep*

Rainwater
I needed a solution for rainwater coming off the roof, guttering is the standard method, the question is where to route the water to.

*Option 1*: Soakaway
*Downsides*: no idea how to build a soakaway

*Option* 2: Tap into drain
*Downsides*: no idea how to tap into a drain

Anyway, there was a drain very nearby that took rainwater from a garage roof so once I excavated a bit I noticed that there was a T junction that looked pretty easy to tap into.
I also measured the fall between the T junction and my expected gutter exit at floor level and it was over '1 in 40' so this looked like a good option and I proceeded to ignore the soakaway idea.

Method
I picked up a few parts from screwfix, some waste pipe, some 90 degree angles, a flexible coupler (because there was slight kink to deal with) and a little rubber thing that goes from waste pipe diameter into drainage pipe diameter.

Pretty straight forward to install - dig a trench, connect the parts up, lay it on soft ground pea shingle in most places, then back fill with soft ground (no rocks or stones).









It doesn't look it but the ground is sloping towards the drain













The next day I had another go at this as I realised that the end of the pipe sticking up out of the ground was visible when viewing garden room from the front at certain angles. So I moved this part further down the side wall which meant getting more parts:
1. longer pipe to extend the distance
2. replacement 90 degree bend because removing the original with a hammer turned out to be a terrible idea - those things really disintegrate!

Decking Ground Prep
At this stage I also got the levels sorted to accept the decking.
I'm planning on using those adjustable plastic plinths that all the decking companies seem to sell - they seem like a nice solution but time will tell. The building is raised above ground level on the right hand side, but not so much on the left hand side (50mm on left and 250mm on right). The timber decking base is 100mm thick which meant it would need to sit 50mm below ground level. But I didn't want the base of the left hand side sitting on the ground, I wanted to ensure it was raised up out of the way of water / moisture sittin on the plastic pedestals . Therefore I needed to dig down a bit on the left in order to have the deck supported at the right height. I also wanted a reasonably flat and solid platform to put the pedestals on. I considered putting down hardcore but decided just to compress the ground with a tamper to create a solid base.

Pedestals
I found out the smallest pedestal size and dug down enough to accomodate both the pedestal and the timber frame (plus a bit of wiggle room). The pedestals come in lots of different sizes from about 30mm up to about 300mm (in fact I think they can be stacked and go even higher, even up to metre or so I'm thinking but you will need to check that). The ones I bought were I think called Rhinodeck or something but there are loads of suppliers for these things. Anyway, they each have a range, for example 50-70mm, or 200-300mm and you have to buy the right ones for your application, and it isn't all that straight forward to work out what you need 




Notice the pile of dirt in this picture that I will 'deal with later'. Turns out 'later' is a time, far, far into the future.... 




Levels and parts ordering
So once it got a bit darker outside, I set up a laser level pointed at the height on the outside wall where the bottom of the timber deck frame would be (this is the same level as the top of the pedestals, obviously). Then I went around with a tape measure on every location of the pedestals and wherever the laser intersected the tape, I noted the measurement and wrote it down. I think I spaced mine every 500mm, they are rated at over a ton each, so the loading wasn't an issue, just span, and with a 100mm x 50mm timber for the base, spanning 0.5m across the supports is not an issue in the slightest.




Here is the 'document' I created telling me the required heights for the individual pedestals.
Once I had the heights I created a simple table of the exact parts I needed and quantities of each and then I went online and ordered them. What could possibly go wrong.




Here are the parts as they arrived, some assembly is required and it isn't as straight forward as I would have liked to assemble them. The assembly takes seconds for each one, but knowing which parts to put together is the slightly tricky part as you have not only different base heights, but also different 'stalk' heights. I had to go on the website and figure out which parts to mate with which other parts in order to build up the actual parts I ordered. I mentioned to rhinodeck that this was harder than it needed to be and they agreed and planned to sort something out better for next time, like a simple chart that comes in the box, rather than just the puzzle pieces.





Martin


----------



## Molynoox

*Aug 2021 - Decking Base*

I thought this was going to be really straight forward, having just constructed an entire building using what I though would be the exact same techniques. The curveball came in the way of the diagonal area. Defo some mistakes made here, and plenty of good learning.

I made a sketch of the basic design of the timber base, but this turned out to be a problematic design.




In future I would do the following:

Use subframes and bolt them all together as you go (this is what I did for the most part, but not when I got to the really complex diagonal section - no, I decided to make that part really hard instead)
make as much of the base as possible using square or rectangular frames, and then finally add in whatever extra necessary to make up the diagonal part or parts.
make sure that each subframe is a reasonable size and is 'self supporting' meaning that it wasn't reliant on some other subframe for its structural integrity.
Do NOT make one massive diagonal component that ends up being a bit of a nightmare to manipulate into place and mate up to the rest of the structure.
Ensure you have timber that is long enough for the longest side of your longest sub frames, rather than having to join two timbers together
Think about how to get the joists fixed if building a 'perimeter frame' first
So in a nutshell, I made a similar mistake as with my base for the main building when I built the 'perimeter frame' first to ensure it was all the perfect size and shape, and then built the interior structure (sub frames + joists) afterwards. This was an ok idea in theory but I didn't plan the subframes and how I was going to get the joists attached to them without toenailing.

Decking boards
A final mistake I made was not thinking ahead enough about the composite decking planks and exactly where they were going to fall and how I was going to attach them. I did space the joists at consistent 400mm centres, which I though would be fine, like it is with sheathing OSB, plasterboard etc, and it was fine for the straight sections, but its not quite that simple when you get to the diagonal parts. The main reason for this is because I have a 'picture frame' design on the decking which means that the edge board uses the edge of the timber frame for support and you then need additional supports putting in to support the ends of the interior planks (because the edge boards are covering up the edges of the timber frame so you cant attach to that). That probably makes no sense so I will move on.
In fact here is a picture from the future showing the 'picture frame'




Anyway, I will cover laying the composite decking later, and talk at that point about how I upgraded my base to neutralise the problems just mentioned.

Decking Selection
When I built the frame, I had already selected the composite decking product as I needed to know the exact thickness of the boards so I could get the threshold perfect (i.e. flush). My boards are 22mm so I needed the frame to sit 22mm below the door threshold.

I received samples from 7 different suppliers then put them all into a selection matrix so I could chose (considering factors such as cost, look, quality). In the end I got the shortlist down to 3 or 4 suppliers and 5 or 6 different products, all in a grey/anthracite colour to match the doors.




Here is the shortlist of 6 products once I had filtered out the wrong colour, poor quality or mega expensive ones




One column I would add in the future to my selection table would be the clips / fixing method, this turned out to be quite important, but I will cover the details of that later.

Decking Frame




Here you can see how I have cut off the edges of the pedestals which are close to the edge of the frame - this is because I wanted the pedestals supporting the bearers and not just the joists and if you have them under the bearers then they protrude out from the frame








Waterproofing
I applied some roofing paint to the tops of the structure. I know that people have had 15 years out of unprotected tanalised timber bases but I figured that waterproofing the tops of the joists where the water might sit will add another 10 years or so on top of that. I did consider joist tape but its crazy expensive compared to the roofing paint option.
_Note_: I do use the tape in the end, but again I will cover that later,,,,









Fixing the base to building
I considered having the base entirely floating because I didn't want any water running off the decking towards the building, but in the end I decided that fixing it to the building would add a lot of stability and would make it feel a lot more solid. Also, I managed to come up with some ways mitigated the risks:

I have a gradual fall on my decking base that runs away from the building (its about 1 in 30 and it look completely flat unless you get your spirit level out - this is actually normal best practice on decking bases)
I have created some weird flanges that bridge the gap between the building and the base, that allow the water to run off safely
I have house wrap covering the building, right down to the bottom
I have used roofing paint on the bottom 200mm of the house wrap
Here are the weird flange things which I made from some plastic trims, screwed together back to back so that water runs away from the building on one side and away from the timber base on the other. This also adds a 20mm gap in between the timber frame and the garden room. In the future I would avoid the faff of making these and try and find something off the shelf like a 20mm cyclindrical spacer that would allow you to screw the base tight to the building but at same time create an air gap for safe water run off.






Martin


----------



## eribaMotters

I'm not sure that you are allowed to divert your rainwater into an existing drain. Whilst the workshop structure is exempt from planning regs the rainwater issue is not. I believe up to 6m2 of roof area is exempt and in the case of a previous garage extension I completed, that had to abide by building regs, the water dispersal was not covered and I was allowed to let it run down the drive and into the road.

Colin


----------



## Molynoox

Cheers Colin, that's good info.
I did actually have a plumber round to look at this and he advised the drain method I showed above. Looks like I might need to look into this a little more, thanks for making me aware of the details


----------



## flying haggis

just look on your roof rainwater runoff into the drain as helping to keep the sewers flushed clean.......... (its where my workshop roof rainwater went..)


----------



## Molynoox

flying haggis said:


> just look on your roof rainwater runoff into the drain as helping to keep the sewers flushed clean.......... (its where my workshop roof rainwater went..)



Some of the rules around these things do seem a little strange - often when you look into it you realise the rationale behind it, and at other times it doesn't make any more sense no matter how hard you look into it. Not sure where this one sits


----------



## Molynoox

eribaMotters said:


> I'm not sure that you are allowed to divert your rainwater into an existing drain. Whilst the workshop structure is exempt from planning regs the rainwater issue is not. I believe up to 6m2 of roof area is exempt and in the case of a previous garage extension I completed, that had to abide by building regs, the water dispersal was not covered and I was allowed to let it run down the drive and into the road.
> 
> Colin



I have now taken a read through Building Regulation Part H, specifically section H3 concerning rainwater drainage, and I see no mention of the 6m2 constraint you mention. The best guidance I could find is as follows:











So this mentions that rainwater drainage requirements are satisfied if the gutters are up to scratch and can handle the rainflow and if the rainwater discharges to a soakaway or surface water drain or sewer. Which mine does.

I have no doubt you didn't imagine the 6m2 constraint but I cant find any mention of it anyway, and would appreciate your help to provide reference to the regulation.

Martin


----------



## eribaMotters

You are in look. It was some time ago, back in 2000, I extended the front of the garage and was able to use the 6m2 rule that was applicable in Essex. Time moves on and we are now on Merseyside and I've had to adapt to regional differences. Don't get me going on footings, but is is suffice to say it's a dam site easier up here on sand than Essex clay.

Colin


----------



## Lazurus

I have just added a 40m2 workshop and I had to install a 1m3 soakaway 5m away from footing and 2.5m away from boundary. I used soakaway crates I could have broken into the garage downpipe and exit but as this was possibly also a soakaway I decided to put a separate one for the workshop as it would be much harder to do this retrospectively if the existing soakaway was overwhelmed. Around here adding rainwater to foul water is a big NONO and carries quite a penalty, certainly more than a soakaway costs.


----------



## Molynoox

Lazurus said:


> I have just added a 40m2 workshop and I had to install a 1m3 soakaway 5m away from footing and 2.5m away from boundary. I used soakaway crates I could have broken into the garage downpipe and exit but as this was possibly also a soakaway I decided to put a separate one for the workshop as it would be much harder to do this retrospectively if the existing soakaway was overwhelmed. Around here adding rainwater to foul water is a big NONO and carries quite a penalty, certainly more than a soakaway costs.


that's good info, but where / how is this regulated? Is it written down anywhere?
thanks
Martin


----------



## Lazurus

Molynoox said:


> that's good info, but where / how is this regulated? Is it written down anywhere?
> thanks
> Martin



I did a few google searches of various suppliers and installers and they all gave the same guidelines - its in the NHBC riles and regs as below



*5.3.11 Surface water soakaways - NHBC Standards*
https://nhbc-standards.co.uk › 5-3-11-surface-water-soa...



_Soakaways_ should be: · built on land lower than, or sloping away from, buildings · sited at least 5m from the foundations of a building · sited to take account of ...


----------



## Molynoox

thanks, some good info inside that standard, and I will certainly take a read  
Putting aside what is best practice (I don't question *any *of whats being defined in that document) - I have a query specifically about the legality of what you are building (you mentioned a penalty being issued in your area) - I am a little confused here, I thought building regs was the standard which defines if you are building things right and hence defines if you will (or not) receive penalties for doing it wrong?
Are there other standards that you are legally required to comply with?
I hope that doesn't sound argumentative, I just want to understand it.
Martin


----------



## Molynoox

*Aug 2021 - Pergola stage 1*

I did the pergola in two stages, three if you include the planning stage which I explained in painful detail earlier. The multi stage approach was really to work around the weather and material supply issues. Doing the pergola stuff (not really priority item) to fill in time, and then moving to higher priority tasks when weather or material stuff permitted. Great in theory but the staged approach did lead to one decent sized mistake which gave me a bit of head scratching later on.

Stage 1 was placing the posts in situ (plumb in both axis) and _marking up_ the position of the horizontal cross beams, which will be joined together with half lap joints.
Stage 2 was _cutting _the half lap joints in the posts and assembling the structure

Stage 1 and stage 2 were I think 6 weeks apart. Marking and cutting should not be 6 weeks apart. No matter how clear your marking out is, future self will misinterpret it one way or another. And I did. More on that later.

Design
Here is a reminder of the design:





Groundscrews
I used some self install groundscrews as the foundation for each pergola post. These cost I think £20 each + £10 for a 'U' bracket per screw, then we have £45 for a T bar installation tool and £100 for delivery, so about £400 for 9 screws delivered. Not exactly cheap but with expensive Cedar I didn't want the posts sitting in the ground and rotting either so decided that it was a justified investment. It was also a bit of a learning experience - one of the reasons I wanted to go that route.








The Cedar
It does look nice....




....and smells even better

The screws
Following on from the advice I received on a separate thread I bought some Reisser screws, and I'm really happy with them. The big ones are 8mm thick and are a thing of beauty.




Hugeness (not as big as the groundscrews though):









Here is what I ordered with prices, I was quite happy with the costs (I got them from ironmongery direct)




Marking out
I used maybe 15 or 20 clamps to hold all the posts and cross beams in the right place, just so that I could mark up the posts ready for cutting. Lots of messing around with spirit levels, up and down ladders, adjusting things and readjusting things, until every single part was plumb and level. Then I could mark up the half lap joints on all the posts.




Mistake
The mistake happened on the posts at the near edge of the decking (not the posts adjacent to garden room). These posts receive two cross beams, like all the other posts do, but these posts do it at _two different levels_. This is where my marking up wasn't clear enough for future self. I ended up cutting the tops off these posts (just above the lower cross beam) instead of adding a second layer of half lap joints for another 'upper' cross beam - this meant the posts were too short and where only long enough to support the lower cross beam.

_This is problematic post_





The posts are £125 each and on an 8 week leadtime - either way, replacing them wasn't really looking like a great option.

Martin


----------



## Molynoox

*Oct 2021 - Pergola stage 2*

So having measured and marked everything up over a month earlier, I started now cutting the posts and assembling them into a pergola shaped object. The half lap joints on the posts were cut using the mitre saw and were really easy to do, the Cedar is really easy to cut.




_One hit with a hammer and it needs almost zero clean up with the chisel_




_All the half lap joints done - I also added a little chamfer on all edges which is pointless but I really like it..._




_After OSMO oil_




With the OSMO oil you really need to wipe off excess with a rag, I didn't first time around and it was sticky for days. I used a rag next time and it dried in a day. Also, the oily rag is dangerous so don't store near your kindling 

Mistake and bodge fix
So because I accidentally cut 2 of the posts too short and I didn't want to wait 8 weeks for new ones (or pay £250) I decided to extend the posts using another piece of cedar and construction screws. I will later mask my error with some cedar cladding around the base of the post.


















Post section finished, spars are next up

Martin


----------



## Molynoox

*Oct 2021 - Pergola stage 2 continued...*

I was advised by a few people that notches on the spars can reduce the strength of the structure and therefore not necessary - but I did them anyway. I did compromise and make them quite shallow (25% of the wood thickness). I think I just prefer the look of them when they are notched, they look more integrated rather than sitting on top.

It turned out the my mitre saw's trenching feature did not have enough thread on the bolt to cut at the depth that I wanted. I have encountered this issue before and I really don't know why they don't come supplied with a bolt long enough to trench at any depth in the range of the saw. Anyway, I modified the little swinging platform thing by CA glueing a M10 nut on top. This allowed me to cut a very shallow notch in the spars.









One thing I noticed is that this little platform does flex a little bit if you push down on it, so when trenching you get much more repeatable cuts if you take care not to force the saw down into the wood and be very gentle with it instead. By doing this the trench cuts were coming out really clean and consistent but they weren't until I figured that out,

Spars on top




















Views from inside (and the future...)








Overall I'm really happy with how this came out, it completely changes the feel of the garden. It also creates a sort of L shape, or is it a U shape, that makes a bit of a bridge between the garden room and the house, it links it all together. Once I get the little screen things on the back it will feel super secluded. Probably.





Martin


----------



## robgul

Overcome with jealousy - looks fantastic.


----------



## Fitzroy

Super!


----------



## Keefy.

Yup, as said, really nice.


----------



## flying haggis

Are you using clear wriggly plastic sheets on the roof...........

Fetching coat and ducking to avoid hammer.. Looks good really!


----------



## Molynoox

flying haggis said:


> Are you using clear wriggly plastic sheets on the roof...........
> 
> Fetching coat and ducking to avoid hammer.. Looks good really!


Yes, I ran out of bin bags so had to just clamp some EPDM rubber to roof instead


----------



## Lazurus

Check out Screen with envy they do some great products and zero maintenance


----------



## Molynoox

Lazurus said:


> Check out Screen with envy they do some great products and zero maintenance


They look brilliant, defo taking a look around there. Watch this space!
Thanks for the tip 
Martin


----------



## Lazurus

Molynoox said:


> They look brilliant, defo taking a look around there. Watch this space!
> Thanks for the tip
> Martin



Do the usual register for emails etc they do flash sales, I took advantage of a 3 for 2 offer on the screens we purchased, excellent quality.


----------



## The Chiller

Quality


----------



## robgul

Lazurus said:


> Check out Screen with envy they do some great products and zero maintenance



HOW MUCH?!?!? - have to say I think the "wood composite" doesn't quite look the part in my view.


----------



## Molynoox

Funny you say that Rob, I thought the prices might be even higher. Having looked at bog standard b and q type trellis stuff recently that was working out quite expensive anyway and I didn't really like it. I quite like the look of some of the screenswith envy stuff, although it would be nice to see it before buying.
Martin


----------



## Molynoox

Just took another look, I think some of the products are like you say very premium / expensive but I think others are pretty good on value. For example a 1200mm x 600mm (5mm thick) screen for £45 seems pretty good to me, and £60 for 16mm thick option. But then you see fence panels at over £500... so as I say some of it does look quite high end but other products are certainly more 'accessible'.
Martin


----------



## Molynoox

*Sep 2021 - Media Wall Internals*

Going back in time a bit here because I put all the Pergola stuff together, which started early but ended late, not sure that makers any sense, anyway... 

This stage was all about the complex wiring inside the back wall where the TV was going to be mounted (speaker wiring mainly), but this wall also needed to support a TV bracket so everything had to be quite precise.
I had 3 speakers in front wall, and 4 in ceiling, and all the wiring for the ceiling speakers were routed inside this wall through a cable conduit which had an exit at the bottom of the wall.
It turned into a bit of a ball ache to be honest, and if I did it again I would design the walls around the speakers and not the other way around.
Mistake #1
The main mistake here was not really understanding how the speakers mounted into the wall before I received them - the constraint was that they need about 50mm of plasterboard cavity all around the edges so that some plastic lugs can be twisted into place and grab the wall from behind. The placement of my speakers was such that I couldn't accommodate this air gap all around - one edge of the speaker always ended up tight against a stud. It was fine in the end as I was able to attach it firmly by using only 70% of the lugs but not ideal.

I am glad I took millions of photos with a tape measure in the picture so that I knew exactly where every single wire was. This turned out to be a critical step when drilling holes for the TV bracket and knowing where all the safe zones were.

_initial planning with all the cavities cut out for speakers, cable conduit and power socket_




_speakers arrived_








_later stage once all the speaker wire was in place_




_one of my million measurement photos_




_rockwool placed behind the speaker (acoustic reasons, as per Polk guidelines)_




_all 7 speaker wires jammed back inside wall temporarily - I will dig them out later after plastering_





Martin


----------



## Molynoox

*Oct 2021 - Plasterboarding and ceiling insulation*

These two things seemed to happen together, not sure why, I was working a bit randomly for some reason.

Ceiling insulation
Tricky part with this was cutting cavities for the lights and speakers. I could have made things a lot easier by just cutting big holes out that went all the way through the PIR but that would have a created a non-air-tightness situation. This is only really a problem for me because I opted for a vented cold roof design, which means I have airflow passing above my PIR. If I have holes all the way through the PIR it means air can in theory flow into the room space if it can get find a way past the interfaces between plasterboard and speakers / lights.

So I had to perform lots of intricate 'limited-depth' cuts which really slowed things down. I found the best way was to make lots of knife marks and then hit it with a chisel to carve out the cavity. Some of the shapes I had to make were quite complex.
























_white wires are speakers, grey ones are lights_




_vapour barrier, stapled to joists_








_laser was handy for finding studs_ quickly





In the end I paid somebody to do the ceiling plasterboarding as I just thought it would be a nightmare on my own, and the plasterers did it all in a day so probably way quicker than I would have done it

Martin


----------



## Molynoox

*Oct 2021 - Plastering and Flooring*

Got a quote for £2800 for plastering and another for £1000. Seems to be a pretty wild range. I went with the cheaper one, and the overall finish was fine but the customer experience wasn't as they left behind all the plasterboard waste (including two full sheets which they didn't use!) which may or may not be normal practice, but either way it bugged me quite a bit.

In terms of flooring we couldn't decide between the Wickes laminate and the Wickes Vinyl stuff, so bought both and I did the office side in Vinyl and the workshop side in laminate. I actually prefer the laminate to the Vinyl, which was actually cheaper. I did look in places like John Lewis and Howdens also but honestly couldn't see why I was paying 3 or 4 times the price of the Wickes stuff. Maybe time will tell.

I acquired the below samples and quote from Howdens - engineered stuff was much more expensive than laminate, and honestly, although it looked different, it looked no better (to me) from the top, which is the bit you see. The laminate was basically identical to Wickes stuff from what I could see, just more expensive. I am not having a pop at Howdens, just passing on my thought process. If I had infinite cash I would probably have chosen the engineered stuff, just because its 'real' wood, but at the end of the day if it doesn't actually look or feel any better on a day to day basis then its hard to justify.




Anyway, here are some pictures.

_Wickes laminate stuff_




_Vinyl option in office_





















_Laminate stuff in workshop side_












both options were fast and easy to fit, and took maybe a day each. If you knew what you were doing you could probably do them both in a day.

Martin


----------



## MARK.B.

Looking good all freshly plastered,not a criticism and i may have missed a previous post but, I can't see any electrical sockets


----------



## Molynoox

haha, the sockets are all hidden behind the wall at this stage - they will make an appearance soon, providing the measurements we took are accurate....
Martin


----------



## Molynoox

*Oct 2021 - Painting and skirting*

Not a lot to say is there, I opened a tin of paint and transported it to the walls in the normal way via paint roller with the usual splatterfication side effects. I hear a lot of talk about diluted the first coat with water for fresh plaster, but it's something I never done and I've never had a single issue. I just open the paint, stir it and off I go.
It took two coats to get it looking like it does in the pictures. I don't think I bothered to add a third as its probably going to get painted a proper colour at some point when (or if) we can be bothered.

Skirting was not something I have attempted before but other than handling lengths of MDF which are very long and annoying it was pretty fast and easy to do. I did that funny curvy profile cut at the ends with a coping saw to get them to fit together nicely, that bit took a little experimentation but was fast once you have the method worked out.

_coverage with one coat_





coverage with two coats








_skirting stuff_








_architrave round the door_

















I am rambling a lot less in these later posts 

Martin


----------



## MARK.B.

Good ole pinkgrip sticks like  to a blanket


----------



## Molynoox

*Oct 2021 - Interior details and electricity*

Fitted a door, that's another first, seems to have turned out fine though, consistent gap all around etc. I enjoyed doing it actually, bit of chisel work.













_Fitted the TV bracket and the installed the speakers into the walls and ceiling_









_Not enough gigantic holes in the ceiling for my liking so created this one, I had to cut into the ceiling joists a little, but they were slightly overdesigned in the first place and also the hole was in a lucky place as the ceiling is actually supported in the middle by the bathroom partition wall._




its actually going to be a 1200mm x 300mm light panel once installed

_Sockets appearing.....







_
some electrification happened also, as evidenced by the one billion lumens lighting. Joking aside the lights are quite nice, they are Collingwood diffuse downlighters (I think they are called 'Thea'), and I think they are about 1500 lumens each or something but the diameter of them and the diffuse panel helps reduce the impact somewhat. Also dimmable as they are on a dimmer circuit, which is handy because full power is only really useful if doing DIY dentistry or surgery I imagine.

it's starting to look and feel a bit like a room now, wahey ....

Martin


----------



## Molynoox

*Nov 2021 - Bathroom stuff*

Started to fit some of the bathroom stuff at this stage, although it didn't get fully plumbed in until a bit later.
Here is the plan which I gave to the plumbers to help them plan ahead and get the necessary parts. They did the usual and completely ignored it, then turned up and spent the next 3 hours driving to various screwfix stores to get all the bits they needed because everything is out of stock.
"Oh, you want a washing machine there, ah well I will need a blah blah for that... " 





going back in time a little, but here is the inside of the walls. I used sound insulating rockwool because I figured the washing machine might be a little noisy, and I also used 4 x 2 studs which was structurally probably overkill but it allowed for more sound deadening to be installed.




_various bits going into place_








_had to modify the cabinet to fit the water heater in by raising the shelf - not quite as easy as I thought it would be, things never are, are they...._













Martin


----------



## Molynoox

*Nov 2021 - Cladding (sides and back)*

The cladding has arrived - this stuff is only getting used for sides and back; for the front I will use something more decorative (TGV Cedar). The cladding is called Pioneer from Envirobuild and I really like it, its a composite cladding. It has a nice matt sheen to it and looks quite premium. I could probably have used something a bit cheaper but I figured this would essentially be maintenance free, and that really appealed to me (fit and forget). I also considered the anthracite metal box section stuff that a lot of people are using now, but I decided against it in the end, honestly can't remember why but I think I had concerns over the window detail despite getting some good advice on here. There may have been other reasons, like leadtime, but I cant actually remember them.

_all the cladding needed for the back and sides.... provided the building is 10% smaller than it actually is, which is why I later had to order more_




_first few boards fitted_





The one thing that annoyed me with Envirobuild is that they don't sell the screws needed to attach the cladding, but they DO specify what you need to use. So you have to interpret the spec they provide (which was weirdly defined and didn't actually throw up a single google hit) and then try and find screws that match that description. Normally this wouldn't bother me in the slightest but its really not straight forward getting screws that work as they need to be pan / washer head, and also quite short, which is quite an unusual combination. But added to that not all pan heads will fit as the space in the cavity for the screw is quite tight, and there is also massive screw supply issues at the moment so you can't get hold of the very few that actually fit. So you basically have to order loads of different ones from screwfix and then take back the ones that don't work out. I was also having to buy the screws from multiple screwfix locations because they typically only had one packet in each. So that was fun.
Note: when I say screwfix, I mean screwfix/toolstation 





I had to fabricate some support blocks for the top boards because when you cut off the tops they are not as 'deep' - this seemed really weird but I couldn't see any other way to do it and the fitting guidelines just ignore 'details' like this 




_behold the rarest of finds, a screw that fits into the gap...._





similar problem around window detail with the reduced 'depth' of the board once cut to size - I used OSB this time and attached to the wall, which was easier than previous attempt fixing blocks to the board itself....









you can also see the bathroom extractor fan outlet in this picture, also known as 'a problem for another day' or it's alternative name 'out of sight, out of mind'

I do have some corner trims that will be fitted to finish off the window reveals but that is also a problem for another day.
Martin


----------



## Setch

The issue with not thinning the first coats on fresh plaster plaster will only come back when you redecorate. I did my kitchen wall and ceiling straight over the plaster and/or plasterboard. No issues at the time, but 5 years down the line I had building work done, and the paint is not remotely stuck to the plaster. Dust sheets were put up with duct tape, and they took the paint off back to bare plaster. Worse, where I have overpainted, the paint bubbles and lifts off, again back to bare plaster. This will mean peeling the whole ceiling and 1 wall bare and repainting the whole lot, instead of touching up here and there. 

Too late for your (superb looking) garden room, but I'd hate anyone reading this to assume the concept of mist coating is nonsense, and find to their cost that it isn't.


----------



## Molynoox

Setch said:


> The issue with not thinning the first coats on fresh plaster plaster will only come back when you redecorate. I did my kitchen wall and ceiling straight over the plaster and/or plasterboard. No issues at the time, but 5 years down the line I had building work done, and the paint is not remotely stuck to the plaster. Dust sheets were put up with duct tape, and they took the paint off back to bare plaster. Worse, where I have overpainted, the paint bubbles and lifts off, again back to bare plaster. This will mean peeling the whole ceiling and 1 wall bare and repainting the whole lot, instead of touching up here and there.
> 
> Too late for your (superb looking) garden room, but I'd hate anyone reading this to assume the concept of mist coating is nonsense, and find to their cost that it isn't.



brilliant  I do like it when people explain the why and not just the how.
advice fully absorbed, cheers, and you were right to correct me.

Martin


----------



## Molynoox

*Dec 2021 - Composite Decking*

It feels like I'm getting close to the end now. I wont be sorry to see the back of the decking frame which I am quite bored of looking at and tripping over every day.

After much research and staring at samples, I eventually settled on a product from NeoTimber. My wife was also very helpful in the selection process, conversations mostly went like this:
me: "do you like this one?"
her: "yep"
me: "what about this one?!
her: "yep"
me: "this one?"
her: "yeah, fine"
me: "you don't care do you?"
her: "nope"

she was right, they did all look the same, pretty much

_here is the pile of stuff, pairs of boards were individually wrapped in clear plastic, no idea why_




I opted to do a 'picture frame' style on the decking because that seemed like the most complex way possible and that fits in with my theme 













Going well so far, quick and easy, gaps looking consistent, piece of cake! so far....

the cuts adjacent to the building were a little tricky, not the fiddly measuring part, mostly just executing the long 3m rip cuts with bits of semi-accurate jigsaw work thrown in for good measure, for the cill cutouts. I found the best method was to cut the boards outside on the decking, taking care to put in sacrificial supports and DOUBLE check the depth stop on the saw. At this point I didn't have a track saw, and was using a home made OSB rail solution and my regular non-track 36v circular saw (composite boards need a fair bit of power as your blade will no doubt be blunt after the first 10 seconds).

I admit I did buy a track saw almost straight after this experience as the DIY OSB rails were skidding around, and clamping them wasn't easy because there wasn't enough space under the board because I was only using 11mm OSB as sacrificial boards - basically it just felt like way too much effort for a single cut and the amount of faffing around was quite ridiculous. Oh yeah, add in the fact I couldn't see my pencil marks up against the dark boards (no I don't have a white pencil) not helped by the rain which kept washing the marks off, and I was starting to wonder why it was taking me an hour to cut one single board.

Future plan:
white pencil + track saw













_these are the screws you need when you run out and cant be bothered ordering them through a specialist decking company - very difficult to find some with heads small enough not to sit proud. _




Notice also the waterproofing on the decking frame, I used decking tape on the tops and roofing paint on the sides.

It got quite fiddly around the posts, with the diagonal boards and what not, but it turned out pretty good









Also plonked the egg chair into its rightful home, and was pleased that it fitted, especially seeing as I designed it that way. Nice to get it off the grass, but even nicer to get it in position as the whole thing is starting to feel close to finished now. Hurrah.

By the way, I have no idea what I'm doing with composite decking so if anybody spots any mistakes please let me know, thanks
(obviously it's not finished yet, still need to do the step and the edge stuff)
Martin


----------



## Molynoox

*Dec 2021 - Decking step quick update*

I spent the best part of a day messing around with the step, not quite sure why it took that long but it did. I decided that I would make it two boards deep as that felt about right (I know there is a mathematical rule for calculating height and depth etc, but I didn't follow it as I wanted the step quite compact because reasons).
I decided to do 45 degree angles on the sides so it blended in a bit better than simple 90 degree edges, which meant two 22.5 degree cuts on the top for the mitres of the boards at the side. You really need to look at the picture as none of that makes sense...





The structure of the frame ended up being quite substantial due to where I needed support for the individual boards. This si the exact same problem which I didn't really plan ahead enough on the main decking itself. Typically I need to make a mistake twice to learn from it so I'm hoping that next time I nail this straight out of the blocks.

I sketched an improved joist design on the floor as a reminder to future self about what I did wrong and how to do it better next time. In reality I could probably simplify even further by just using 6 x 2 timber or something.




I had to use some 1mm yellow (they didn't have to be yellow) spacers at the edges - the reason for that was because the fast clips (as they are called) are about 1mm high which raised the board at the joins and created a very small angle front to back at the mitred joints, that probably nobody else would ever notice, but bugged me enough to sort it out. You wouldn't get this 'problem' if you used starter clips at the front edge of the boards near the edge of the support frame (because those are also 1mm), but I wasn't using them (despite ordering loads of the things)





Overhang
the reason for not using the starter clips (these are specifically designed for the front edge of the initial board, and not where two boards join) was because I have an overhang at the front edge to accommodate some poncy LED lighting that will run all the way around the decking and point down at the ground. This overhang is 40mm (22mm to accommodate the board which will be used to trim the edges/sides and 15mm for the LED strip conduit + a 3mm buffer)

The downsides to doing this is that you can't use the starter clips and hence need to use the special colour matched decking screws, which are then visible, but to be honest they are quite non-visible unless you go looking for them; check out the pictures 

Clipping system
Just a final word on clipping systems, if I did this again I would not use the 3mm wide metal 'fast clips' again - they just don't work quite frankly - I would instead use the 6mm plastic ones that have 'secret' fastenings accessible through the gaps in the board joins.
With the metal ones, you have to modify them for some of the boards (those at the building edges) by hammering down one of the 'hooks' or you will never get the last board in. I did try using the starter clips for this but that didn't work either. You also need to use the colour matched visible screws through the board face in some places for a similar reason. Finally, if you ever needed to remove a board it would be impossible with these clips unless you took the whole deck up.

As a full discplaimer, I don't have any experience with the other design (which I didn't use but wish I had), other than what I have seen on yoututbe etc, but they do look like a more well thought out solution to me. But I could certainly be wrong.

Martin


----------



## Glitch

Molynoox said:


> Just took another look, I think some of the products are like you say very premium / expensive but I think others are pretty good on value. For example a 1200mm x 600mm (5mm thick) screen for £45 seems pretty good to me, and £60 for 16mm thick option. But then you see fence panels at over £500... so as I say some of it does look quite high end but other products are certainly more 'accessible'.
> Martin



I put a Screen with Envy panel in my BBQ shelter to fill an opening.


----------



## Molynoox

Glitch, how come you've only got 4 barbecues in there? That's only two per person looking at the seating arrangements.


----------



## Molynoox

*Jan 2022 - Cedar Cladding*

Finally got around to doing the Cedar cladding on the front. I was looking forward to this one as I felt like it would all come together once the cladding was in place. I was only partially right about that one, because now that the cladding is done I just see all the other things still left to do, such as the decking fascias and the path / patio.
But its a big step forward and its feeling close to done so I'm happy.

I decided to go for horizontal cladding, the vertical looks nice too but I think I'm a bit bored of seeing vertical so I went with horizontal. Now that its done I do think I prefer it.
The Cedar came from Silva Timber, and it is the 142mm 'Prestige' boards which are classified as 'No.2 clear and better' which basically means it has been hand selected and there are no defects or knots in the wood. It also means that you will need a small mortgage to pay for it so it's best to sit down before looking at the price.
Everything was fastened in place with 50mm stainless steel nails - I tried the secret nailing technique but it wasn't working out so fastened direct through the face (as recommended by all the Cedar cladding suppliers)

Window details
OK so question for those with experience; how do you do around the windows with TGV boards? See below for how I did it, not sure this is the best way? It felt kinda stupid but I couldn't think of a better way.






Roof detail
I put a bit of thought into this part.
My roof is a vented cold roof, meaning there is a 50mm air gap above the 100mm PIR. The air can move between front and back because there are vents in the soffits at both sides. My problem is that I don't like the look of the normal vented soffit boards you can buy. But I do need to vent it, so I need an alternative.

So what I decided to do was first cover the soffit with mosquito netting to keep out insects etc and then cover it with cedar battens with 10mm spacing between each batten to allow it to breathe. I figured this would be both functional and also look pretty cool. I'm happy with how it came out. It also allows the passage of air from the bottom of the cladding up to the top of the cladding, so it should stay nice and dry behind the cladding too.

In case you hadn't guessed it from the clue in the picture, the netting is stapled in place.




Here you can see the first two battens going on at the leading edge, over the top of the netting.





I was going to paint the joists black so that they weren't visible but after some experiments with the netting I decided that they wouldn't be visible through the netting and through the gaps in the battens so I didn't need to bother painting them in the end.

I was pre-nailing the battens with 400mm spacings before offering them up and nailing to the joists with 50mm stainless nails. This is because it's quite a faff trying to hold a batten and hammer in a nail all at the same time. I was using 10mm plastic spacers to get the gaps consistent.









Window Trim

I quite liked the clean look of the windows without any trims and thought about leaving them without frames, but i figured it might look better with some and it would also be more waterproof so decided to add some.
Here is how the windows look *without *trims / frames:




I made the reveals from cedar cladding boards by ripping them down into two 60mm strips.
I also made the window trims (architrave?) from cedar board but I realised that this was problematic as the boards have grooves in the back which are visible from the sides. To solve this I needed to cut some tiny strips of cedar and glue them into the grooves. Quite ridiculous but needs must. You can see the little additions in the pic below:






Here is how the windows look with the trims added.
You will notice that I didn't mitre the corners - this is because (apparantely) the wood movement through seasons will open up gaps at the corners if mitred. So I created that sort of crossbar type look instead. I also added a roundover to all edges other than where the horizonatal meets the verticals, which I left with a 90 degree sharp edge so that it mated up without a gap.
I think the trims look good - but I am undecided if I like the untrimmed look from previous picture better. 





I need to add the Osmo oil to finish the look and to protect it but it's already looking pretty nice  

Quick tip on the Osmo oil - don't buy the 'Cedar' stuff and apply it to Cedar, that will darken it - get the 'clear' and that will enrich the Cedar tones. If you apply 'Cedar' Osmo to cedar it will add an additional / artificial cedar colour over the top of your existing cedar wood.

Final picture






Martin


----------



## Molynoox

I said it was the final picture, but I lied:














oh look, it's raining:





Doors fully open:









We stashed the egg chair inside the garden room overnight during the mega storms. None of my cladding came off in the 70mph winds, and it all stayed watertight and windproof so that was a good test.

Martin


----------



## Fidget

Very nice Molynoox 

I'll bet you feel rightfully very proud of how it looks.

I'm afraid there will have to be one more 'last photo' when the garden has been tidied up and the black plastic has gone. It will look fantastic

I built a simple garden shed last year and every time I look at it I say to myself 'I did that' and have a little smile


----------



## Keefy.

Yup, that is very nice. Well done you.
Thanks for sharing.


----------



## Glitch

That looks excellent. Well done!


----------



## Glitch

Molynoox said:


> Glitch, how come you've only got 4 barbecues in there? That's only two per person looking at the seating arrangements.



Yes, only 4 BBQs in our empty nest.

I've sold two since that photo and swapped over to a better looking ugly drum smoker.

Bought 2 more to upgrade the collection 

Might sell the portable gas one that was an impulse buy in a B&Q half price BBQ sale.

Bit of an obsession. I BBQ all year round (under a parasol pre-shed) and haven't cooked meat indoors for several years.


----------



## Fitzroy

Fantastic, well done, great job!


----------



## Molynoox

Fidget said:


> Very nice Molynoox
> 
> I'll bet you feel rightfully very proud of how it looks.
> 
> I'm afraid there will have to be one more 'last photo' when the garden has been tidied up and the black plastic has gone. It will look fantastic
> 
> I built a simple garden shed last year and every time I look at it I say to myself 'I did that' and have a little smile



Haha yes I am sure I will add some more pictures as I am still working on a few additions that should finish it off.

I know what you mean about the shed and thinking 'i did that', it does feel good 

Thanks for the nice feedback 

Martin


----------



## Molynoox

Glitch said:


> Yes, only 4 BBQs in our empty nest.
> 
> I've sold two since that photo and swapped over to a better looking ugly drum smoker.
> 
> Bought 2 more to upgrade the collection
> 
> Might sell the portable gas one that was an impulse buy in a B&Q half price BBQ sale.
> 
> Bit of an obsession. I BBQ all year round (under a parasol pre-shed) and haven't cooked meat indoors for several years.


Wow that does sound obsessive, you have a very cool BBQ shelter there so I'm not surprised you cook outside, looks brilliant.

I've bought some screens, I will post a picture at some point and add to this thread.

Martin


----------



## cerro

Did you have to have planning permision


----------



## Molynoox

No, it isn't required for this build. The addition of a bathroom got me looking into building regs and building control, but in the end I avoided that too.
I did a post about planning permission earlier in this thread, there are more details there, but if you have some specific questions please just ask.
Martin


----------



## Molynoox

*Mar 2022 - Screens, patio and lighting

Screens*
I bought some screens from 'Charles and Ivy' and fixed them to the pergola, they are just what I was after so thumbs up for composite screens. Simply screwed in place, couldn't be easier.

*Patio*
I also made a patio / path.
Porcelain tiles from Tile Giant - happy with those too. I put down 100mm of MOT type 1, 50mm at a time and compacted manually with a tamper. Took me 2 weeks to do the foundations - could have been far quicker if I had hired a wacker plate. Sharp sand / cement mix, 5 to 1, on top of the MOT type 1, between 30 and 50mm thick. Slurry primer applied to the back of the porcelain tiles before laying them. I used a 1 in 40 fall for drainage, sloping away from the house. I also put in 150mm wide trench next to house, filled with small stones (Cotswold buff) because the height of the tiles was close to the '150mm above DPM' limit. I thought that would help prevent splash from rain.
I still need to grout the tiles.









*Lighting*
Added two more 'up and down' lights on the pergola, some festoon lighting from Amazon, and also pimped up the decking with LED strip pointing down at the ground. I used fully IP rated LED strip and installed them in a metal conduit with a diffuser panel over the top. Despite being quite a lot of effort, I'm not sure how I feel about the LED lighting. They do look spectacular, but there are two things that bother me a bit:
1. They are 'warm white' 3000k and yet they appear noticeably cooler than the wall lights. I'm not sure if this is because the wall lights are bouncing off the Cedar and making it look very orange, or because there is a genuine temp diff in the bulbs in both sets of lighting. Or a mixture of both.
2. The LED strip is very bright - once its completely dark they sort of overpower the other lighting a bit, and I'm not sure it does much for the 'ambience' if that's the right word.

So I'm not sure if the LED lighting is really needed, or if I should have just stuck with the up and down lights and the festoon lights,

Interested in other people's opinions on that one.

















Last jobs remaining:

1. Grout the tiles
2. Topsoil to sort out the levels and grass seed. 
3. Oil the Cedar cladding
4. Sort out the workshop interior with benches / cupboards etc

Martin


----------



## Jameshow

Is there anyway of hiding threads from the Mrs...!


----------



## Marcusthehat

Wow, mucho impressed!


----------



## flying haggis

very nice indeed


----------



## Humf

Hi Martin

Great read, thanks.

I’m currently planning a very similar build, although located in AONB and well over 50m from dwelling house so planning req’d.

One aspect I’m currently mulling over... the old chestnut of metric/imperial, sheet materials and reduced cutting/waste.

I noticed you went for 400mm spacing (not centres) on floor joists as this allows minimal cutting of PIR. However, you went with 400mm centres on wall studs? What was your thinking with this? 

It seems to me that whatever you do, something ends up needing cuts. Hard to win either way.

For example, going with 450mm centres on wall studs, works well for PIR but leaves cuts for outer OSB.

Thanks in advance for any thoughts you have on this!


----------



## Jameshow

I'd go for 400 c2c pir is easier to cut.


----------



## Humf

Point taken. But pricier to waste?


----------



## Adam W.

That looks fabulous all lit up like that.


----------



## Molynoox

Humf said:


> Hi Martin
> 
> Great read, thanks.
> 
> I’m currently planning a very similar build, although located in AONB and well over 50m from dwelling house so planning req’d.
> 
> One aspect I’m currently mulling over... the old chestnut of metric/imperial, sheet materials and reduced cutting/waste.
> 
> I noticed you went for 400mm spacing (not centres) on floor joists as this allows minimal cutting of PIR. However, you went with 400mm centres on wall studs? What was your thinking with this?
> 
> It seems to me that whatever you do, something ends up needing cuts. Hard to win either way.
> 
> For example, going with 450mm centres on wall studs, works well for PIR but leaves cuts for outer OSB.
> 
> Thanks in advance for any thoughts you have on this!


Hi
You are right about metric and imperial being a bit of a nightmare, however you can avoid it.
FLOOR
The floor isn't any issue regarding cutting the boards as you don't need the joins of the boards to land on a joist. So basically just maximise spacing for PIR on the floor and zero waste.
WALLS
with walls you would normally need to cut down imperial OSB sheets to be compatible with metric stud spacings, OR you would need to space the studs with Imperial but then you have the problem that plasterboard comes in metric sizes, and would need cutting
SOLUTION
My solution was originally to use 11mm OSB which DOES come in metric sizing
However, in the end I needed to use cement boards for sheathing, due to fireproof regulations, which comes in metric anyway. But 11mm OSB is the solution.

By the way, the roof is the same deal as the floor, metric spacings because the boards don't need to land on a roof joist.

Did that make sense?

Martin


----------



## Molynoox

Adam W. said:


> That looks fabulous all lit up like that.


Thank you Adam 
Martin


----------



## Humf

Yes makes sense thanks Martin.

Floor...

I’ve previously used 18mm ply for flooring (albeit on smaller non-insulated ‘practice’ sheds ) again sold in imperial. And I did line up the joins with joists.

I’m assuming the T&G boards don’t need joins fixing? If so, a good reason to use instead of ply. For my sheds, the ply was the final finished surface so better in that situation I think, resilience wise. 

Roof... plasterboard would need to land on centres?

Walls... I notice Robin C mentions 11mm OSB is available in 2700mm lengths, divisible by 450mm into 6. This seems like a neat solution?

Excuse the slightly muddled thinking. I’ve had to put my sketches away because I was finding the question of centres and sheet materials utterly confusing. Then I discovered your thread. So thanks!


----------



## Molynoox

Humf said:


> Yes makes sense thanks Martin.
> 
> Floor...
> 
> I’ve previously used 18mm ply for flooring (albeit on smaller non-insulated ‘practice’ sheds ) again sold in imperial. And I did line up the joins with joists.
> 
> I’m assuming the T&G boards don’t need joins fixing? If so, a good reason to use instead of ply. For my sheds, the ply was the final finished surface so better in that situation I think, resilience wise.
> 
> Roof... plasterboard would need to land on centres?
> 
> Walls... I notice Robin C mentions 11mm OSB is available in 2700mm lengths, divisible by 450mm into 6. This seems like a neat solution?
> 
> Excuse the slightly muddled thinking. I’ve had to put my sketches away because I was finding the question of centres and sheet materials utterly confusing. Then I discovered your thread. So thanks!



I'm really pleased the thread was useful for you, I put in quite a bit of detail, knowing how much effort I spent learning all that stuff and figured it might help somebody.

The T&G boards are PU glued together at the joins and also PU glued down onto the joists. They are also screwed down to the floor to stop them creaking. I reckon some people would advise landing the join on a joist, so make you own decision on that, but once its all glued together and screwed down its not going anywhere and I really don't think you need to land each join on a joist.

Roof... yes plasterboard needs to land on a joist. I think you can avoid doing that if you use super thick plasterboard (so it doesnt sag in the unsupported areas), but that is going to add cost and weight, and there is no need when you can just use metric spacings and avoid the hassle.

Yes I've seen RC using that 2700mm stuff, pretty neat if laying it down horizontal as it works out with nice spacings and no waste on the boards (width wise) if you use the 450 centres.
for a shed / garden room it might not work out any better than 'regular' metric board - depending what width that OSB comes in, I believe the 2700mm stuff is still 1200mm wide. my garden room internal walls are 2.05m at the back and 2.15 metres at the front - so the 2700mm would give no benefit on board utilisation as you would end up stacking two boards on top of one another to get the height, with same amount of waste as with a normal 2400 x 1200 board (a 1200mm board, in vertical orientation sits perfect across 4 studs @400 centres, but you need to cut the top for a 2.05m/2.15m wall)

I suppose the advantage of the 2700mm board is that the 450 centres could be nice for PIR utilisation because that gives a spacing of about 400mm. I think this is probably what you were thinking all along and I've just taken a little while to get there   
However... if going 450 centres you couldn't use 2400 x 1200 plasterboard on inside... but I think you can get it in 1800 x 1200, so that could work if laid horizontally.... Without further thought I reckon that's the way to go unless I'm missing something - thanks for the idea 

Martin


----------



## Humf

Yes that’s where I was going with it...! 

Plasterboard is also available in 2700mm lengths so I think that’s why Robin says it works so well.

In terms of wall height, that’s a very good point about internal height and I’ll have to give it some thought. Externally though, since I’m having to apply for permission and also aiming for a pitched roof, I can (attempt) a design to suit materials to some extent. Two sheets of horizontal osb give 2.4m which will include double wall plate, stud, sole plate, plus some overhang to cover flooring and over floor frame, so not unreasonable without cutting I don’t think. Internal height needs some thought ... I guess it’s similar but minus the floor joist overlap & T&G thickness? (c. 100mm + 18mm = 120mm).

I noticed you had single wall plate? I’m thinking double because the corners tied up nicely last time and also I’m going to keep frames at a size that I can handle when lifting to upright position, so planning a series of panels rather than larger widths. I found 2.4m widths just about manageable last time. Tbh the more complex walls with kings & trimmers etc almost killed me ...! So the double plate will help me tie the smaller panels together.

cheers


----------



## Molynoox

Humf said:


> Yes that’s where I was going with it...!
> 
> Plasterboard is also available in 2700mm lengths so I think that’s why Robin says it works so well.
> 
> In terms of wall height, that’s a very good point about internal height and I’ll have to give it some thought. Externally though, since I’m having to apply for permission and also aiming for a pitched roof, I can (attempt) a design to suit materials to some extent. Two sheets of horizontal osb give 2.4m which will include double wall plate, stud, sole plate, plus some overhang to cover flooring and over floor frame, so not unreasonable without cutting I don’t think. Internal height needs some thought ... I guess it’s similar but minus the floor joist overlap & T&G thickness? (c. 100mm + 18mm = 120mm).
> 
> I noticed you had single wall plate? I’m thinking double because the corners tied up nicely last time and also I’m going to keep frames at a size that I can handle when lifting to upright position, so planning a series of panels rather than larger widths. I found 2.4m widths just about manageable last time. Tbh the more complex walls with kings & trimmers etc almost killed me ...! So the double plate will help me tie the smaller panels together.
> 
> cheers


I think its a good idea to design your building around sheet materials in your case when you are not restricted to the 2.5m height of permitted development builds. Like you mention though, you still have the incompatibility / difference in height of the external OSB sheathing vs internal plasterboard, by the tune of about 120mm like you say (assuming you want the OSB to terminate exactly at the bottom of the joists - I would probably add another 30mm to help any drips keep away from the joists (assuming you have an air gap at bottom, which you may not, depending on your choice of foundations).

Here is a curveball option for you - put the OSB sheathing on the *inside*, that way it can be 2.4metres and 100% compatible with the plasterboard at 2.4m. It's actually technically better that way for condensate / moisture control too, although it probably doesn't feel like it if you listen to your instincts and look at what majority of builders do. Check out some of the shed building stickies - they talk about this option I think. Presumably you still have house wrap to cover up the PIR and studwork on the outside, and also the cladding / metal sheets.

For the wall plate (by the way I think the correct terminology is top plate for what you are refering to - wall plate is something slightly different). The reason I used only one is because that is all that is necessary if your studs are lined up with your roof joists which mine are as both use 400mm centres. I can understand the interest in using an offset between the first and second top plate to help connect things together - personally I prefer to connect the walls without that feature so I can tune it for plumb in situ without being restricted by the geometry of the top plate.

I also relate to your experience of lifting heavy walls - my biggest was a 5m length with a window and it was very close to my limit  my walls are built using 5 x 2 also, so probably 25% heavier than most others - which I didn't really think about until I was lifting it....

you might want to do a build thread by the way.

Martin


----------



## shed9

The before and after view of that (going back to the start of the thread) is stunning.

Superb job.


----------



## Molynoox

thank you Shed9,. Considering our garden before (and for the last 15 years) neither my wife or I can believe it when we walk out into the garden sometimes  "Is this really ours?" 
Can't wait for the summer, I think it will be the first time we have had a garden we can sit in and feel relaxed instead of looking around and seeing things that need sorting out
Martin


----------



## Humf

Interesting. I had seen this in Mike’s design as well as others online. But like you say, hard to adjust when the majority of framing you see online places OSB on the exterior. I was probably thinking of doubling up and using osb on outside and inside of the frame. However, concern with that would be trapping moisture within the frame.

Ok - back to the drawing board with an internal wall height of 2.4m and just the breathable membrane, battens and wood cladding on outside.

I’m not yet sure about size of floor joists. We have incredibly rocky ground and the least amount of excavation the better for my wrists! I’m thinking concrete piers and the least possible, so it helps me to push spans and go for studier timber sizes eg. 6x2. I’m getting a local architectural tech to draw up my sketches so hoping he’ll assist. If not, we can get some structural calcs done. Anyway... my 100mm osb overlap was simply there to cover the join between bottom plate, floor sheets and joists. It doesn’t need to extend all the way to the bottom of joists, just enough to cover the above. I suppose with this new design (no external osb) it’s just a case of extending the breather membrane and battens below the bottom plate (sole).

Thanks for the correction on terminology... there does seem to be quite a bit of variation out there! I guess some of it is UK/US variations? Top and bottom makes sense to me anyway!!!


----------



## Jameshow

If using Pir tightly fitted then your unlikely to get condensation between OSB and insulation much like sips. Just DIY.....


----------



## Molynoox

Humf said:


> Interesting. I had seen this in Mike’s design as well as others online. But like you say, hard to adjust when the majority of framing you see online places OSB on the exterior. I was probably thinking of doubling up and using osb on outside and inside of the frame. However, concern with that would be trapping moisture within the frame.
> 
> Ok - back to the drawing board with an internal wall height of 2.4m and just the breathable membrane, battens and wood cladding on outside.
> 
> I’m not yet sure about size of floor joists. We have incredibly rocky ground and the least amount of excavation the better for my wrists! I’m thinking concrete piers and the least possible, so it helps me to push spans and go for studier timber sizes eg. 6x2. I’m getting a local architectural tech to draw up my sketches so hoping he’ll assist. If not, we can get some structural calcs done. Anyway... my 100mm osb overlap was simply there to cover the join between bottom plate, floor sheets and joists. It doesn’t need to extend all the way to the bottom of joists, just enough to cover the above. I suppose with this new design (no external osb) it’s just a case of extending the breather membrane and battens below the bottom plate (sole).
> 
> Thanks for the correction on terminology... there does seem to be quite a bit of variation out there! I guess some of it is UK/US variations? Top and bottom makes sense to me anyway!!!



How big is the building?
Could you not just use span tables to get the right size joists rather than get structural calcs done? That's what I did for my floor and also my roof.

I've been thinking about this OSB on inside thing and I can't think of any reason not to do it other than a few minor things.
1. electrical second fix might be more hassle because there is OSB and plasterboard to cut through to fit the sockets. Not exactly a deal breaker.
2. No service void behind plasterboard to put the electrical wiring, assuming the PIR is tight up against the OSB on inside.
3. The PIR isn't 'sandwiched' unlike with traditional method, unless you count the breather membrane, but not sure if that is going to be as robust.
4. You *might* not be able to build the wall flat, including sheathing, breather membrane, battens, which is more efficient than doing it when it's upright. I'm again thinking of sequencing of the electrical first fix and how that works with this method.
Martin


----------



## Humf

Same size as yours about ideal for the plot. Although I can fine tune now to make the whole build more straightforward.

Span tables... yes, although I have to hold my hands up at this point and say calculating the dead loads is completely out of my current level of understanding.

I think (1) and (2) on your list are solved by battening vertically on top of wall studs before plasterboarding to create a service void and avoid disturbing PIR for any electrics.

Not sure what you mean by (3)?

(4) most certainly is an issue. Might be a workaround though so I’ll have a little dig around...

thanks for your replies on this Martin. Really helpful. If mine can be even half as impressive as your build I’ll be happy.


----------



## Jameshow

An old chippie told me a ratio of 1.5 X joist depth in inches = span in feet.... That was on 16" centres. So 6" spanned 9ft. 

Which works according to this...






Floor Joist Span Tables for Surveyors - Floor Construction | Right Survey


For floor and ceiling construction surveyors can calculate the size, strength and centres/spacing of joists with reference to the data in these tables




www.rightsurvey.co.uk


----------



## Molynoox

Humf said:


> Same size as yours about ideal for the plot. Although I can fine tune now to make the whole build more straightforward.
> 
> Span tables... yes, although I have to hold my hands up at this point and say calculating the dead loads is completely out of my current level of understanding.
> 
> I think (1) and (2) on your list are solved by battening vertically on top of wall studs before plasterboarding to create a service void and avoid disturbing PIR for any electrics.
> 
> Not sure what you mean by (3)?
> 
> (4) most certainly is an issue. Might be a workaround though so I’ll have a little dig around...
> 
> thanks for your replies on this Martin. Really helpful. If mine can be even half as impressive as your build I’ll be happy.


With #3 I just meant that on a 'normal' build you would have OSB on outside and plasterboard on inside, hence the sandwich. With the alternative wall design option the only thing stopping the PIR falling out of the external side is friction and the breather membrane. Probably not an issue, but when I did my build I pushed the PIR, from the inside, tight against the OSB, which was sitting on the outside. So then I start thinking, no problem, just fit the PIR from the other side and push it tight against OSB on inside, but then you don't want it tight on that side because you want a service void, and in addition it would be a monumental ball ache fitting PIR via the external side as I only left 400mm space around the sides and back of my building. It's all just frazzling my brain thinking about it, seems like a simple change but it changes quite a lot about how you put everything together.
Probably over thinking it as usual, one of my skills / habits 

I'm glad the discussion is helping anyway, I spent 100's of hours researching this stuff and it seems like a bit of a waste not to share it. Thanks for the feedback on my build too, appreciate it, I am sure yours will be every bit as good as you want it to be 
Martin


----------



## Molynoox

Jameshow said:


> An old chippie told me a ratio of 1.5 X joist depth in inches = span in feet.... That was on 16" centres. So 6" spanned 9ft.
> 
> Which works according to this...
> 
> 
> 
> 
> 
> 
> Floor Joist Span Tables for Surveyors - Floor Construction | Right Survey
> 
> 
> For floor and ceiling construction surveyors can calculate the size, strength and centres/spacing of joists with reference to the data in these tables
> 
> 
> 
> 
> www.rightsurvey.co.uk


That's cool James  I'm going to remember that, could be handy when you need something quick and dirty and don't have access or motivation to look at span tables.
Martin


----------



## Humf

Hi Martin

Looking around, 2700mm osb seems to be less common. As you’d expect. Given current pricing and availability of materials this just feels like I’m not going to get the best price. 

What do you think about this idea....

3.6m top/bottom plates, using 450mm centres gives 8 equal studs with 400mm spacing. So the 1200mm PIR is cut into 3 equal strips. So far, so good.

Then OSB sheathing (if using 2400x1200 sheets) can have 2 horizontal pieces and 1 vertical ie. 2400 + 1200 = 3600.

That seems good. I’m only seeing 9mm metric OSB at the moment but will enquire at other yards.

I haven’t yet got my head around sheathing on the inside. I do get it but all residential framing does it on the exterior, so Mike G is bucking the trend on that.

Using 3.6m wide panels does make the overall size a bit tricky. 3 panels would give 10.8m which is a bit big. 2 panels gives 7.2m which is smaller than I would prefer. So I’m thinking maybe using 2 x 3.6 with a 2.4 on the end. This gives 9.6 which is perfect. One 3.6 for the shorter walls is fine.


----------



## Molynoox

if you are having exactly 2.4m height, I seem to remember that was your plan, then your theoretical plan you describe gives near 100% utilisation on the sheathing and PIR, so it looks pretty good to me.

On the inside, you are going to have different wall dimensions to the outside due to the thickness of the walls and how they meet at the corners, so cuts will be needed on the plasterboard, but that is much cheaper than OSB and PIR, so you are doing it the right way round 

you will need to cut your 2400mm x 400mm PIR strips twice again to account for the noggins in middle and whatever is left in top section of wall up to top plate (it will not be exactly right if you have made wall exactly 2400mm for the OSB) 

I haven't gone 'all in' on the internal sheathing yet either

Martin


----------



## Humf

Thanks all understood.

I was really trying to figure out the horizontal dimensions before thinking in much detail about the verticals. Having worked a little bit with plasterboard in the past, i’d much rather be making cuts to that. So if I keep the OSB on the exterior, it would make sense to include 100/150mm of overlap to cover floor joists and take a bit of a hit on internal headroom. Will look at that next!

One thing I’m not understanding, is wall insulation. With a cold roof, I understand that a void is left above the PIR and air is allowed to circulate preventing any buildup of moisture on the roof covering. Moisture is further limited by using a vapour barrier underneath the finished surface. But with walls, if osb is used externally, is the same principle followed? If so, the PIR is kept flush with internal finished surface and a air gap left between the insulation and sheathing, there would be no circulation because of top and bottom plates?


----------



## Molynoox

Humf said:


> One thing I’m not understanding, is wall insulation. With a cold roof, I understand that a void is left above the PIR and air is allowed to circulate preventing any buildup of moisture on the roof covering. Moisture is further limited by using a vapour barrier underneath the finished surface. But with walls, if osb is used externally, is the same principle followed? If so, the PIR is kept flush with internal finished surface and a air gap left between the insulation and sheathing, there would be no circulation because of top and bottom plates?



I went through that thought process too - nobody is venting the walls as far as I have seen.
If you look around at garden room companies, nobody is venting the roofs either  

The problem with condensate is biggest in the roof due to the way that warm air rises upwards and tends to find the roof space and then condense on cold surfaces, hence why moisture barrier on walls seems to be less common / critical in garden outbuildings. I think its a case of drawing the line somewhere but I like your thought process of questioning everything before making the decisions.

Interstitial condensate can in some (possibly most?) instances safely happen inside walls / and roofs because apparantely it dries out again in summer months. But... and its a big but... that really depends how much you use the building and how you use it (with how many people for example)....

Martin


----------



## Inspector

Primary reason for venting a roof is to keep it from getting hot and cooking the shingles. Air traveling from the soffits to the vents along the ridge carry the heat away and is self powered by convection.  

Pete


----------



## Humf

Re. walls. I guess this is the thinking behind internal osb? Any moist air hits the ‘warm’ osb, minimising condensation, and any moisture that does make it through, is able to escape through the breathable membrane?

So the question is really for all those residential buildings and loft conversions that I see the likes of Robin C doing. I think you’ve answered it though Martin with your point about warm air rising and the roof being most susceptible...


----------



## Molynoox

Yep, that's exactly the thinking behind the internal OSB 

Martin


----------



## Churchy00

Molynoox said:


> *Apr 2021 - Beam Calculations (for above the doors)*
> 
> I spent way too long looking into different options for door headers. I was a little paranoid about deflection as I didn't want to have any problems with the doors working properly over time. I have heard of a few people that have had issues with bifold doors and the root cause seems to come back to a combination of:
> 1. the door header not being suitable for the door span + roof loads
> 2. the sensitivity of the door to vertical deflection (but reason 1 seems to be the big one)
> 
> In addition to this, changes in the weather through the seasons can (I have heard) cause flex and movement which can lead to issues. My doors are alu so that means theoretically more stability versus PVC, and hopefully less issues, but the main reason I selected alu was for the sharper looks (if I'm honest). So... operating from the assumption that vertical deflection is the true nemesis of bifolds this became the factor which I needed to focus on and my mind was set on giving my lovely new doors a stress free life via a suitably deluxe door header experience. This meant doing a bit of research into what my best options were.
> 
> Results from my research
> Unfortunately, most of the good guidance I found was for multi storey buildings and hence they were often coming up with solutions that would be not be suitable for a garden room. For my particular application, these recommendations would be either:
> 1. overengineered in terms of strength and cost
> 2. cause me issues on overall building height
> 3. or both
> 
> Mildly relevant distraction #1:
> Regarding the height thing, when working within permitted development you need to keep everything under 2.5m (when building within 2m of the boundary) and for that reason you really need to think about what you are doing every step of the way. For example, assuming 2000mm for your door height, that leaves only half a metre for the base, the headers and the roof (not to mention the air gap under the building, and possibly even your floor boards depending on how you build it).
> 
> Anyway, I'm getting distracted, the point is the only other guidance I found for header selection / header design was pretty anecdotal and didn't seem to have any theory behind it. That isn't necessarily a problem, but on this occasion it wasn't giving me enough confidence to make a decision, considering the potential impact of getting it wrong (fiddly / sticky doors of annoyance).
> 
> The cunning plan
> So... logically, I decided that I would leverage my complete lack of structural engineering knowledge to manually calculate the beam deflections for all of the options available. So here are the options I considered:
> 
> 1. Doubled up 6 x 2, C24 timber
> 2. Flitch beam (C24 timber and steel 'flitch plate' sandwiched together)
> 3. I beam (sometimes known as a H beam or a 'universal beam')
> 4. RHS (rectangular hollow section)
> 
> Note: I did not include concrete lintel or glulam beam, for reasons which I honestly cannot remember, and there may be other options which I dont even know about, that I am hoping people will point out to me.
> 
> My plan was to use the below formula to calculate the maximum deflection on the beam. I would still of course have the problem of not knowing how much deflection was acceptable for my particular bifold door, hmmmm... HOWEVER I would be able to COMPARE them all
> 
> View attachment 117771
> 
> 
> Mildly relevant distraction #2:
> I did contact some of the door manufactures to find out what sort of deflection they think their products could handle, or even what headers they recommended for different spans - but alas, nobody wanted to commit to anything specific, other than to say "computer says no" or "zero deflection required" which is of course theoretically impossible, even if I made it from diamond.
> Note: making it from diamond would represent a significant cost save for the build, considering how much I'm planning to spend on materials and 'essential' tools so far)
> 
> Mildly relevant distraction #3:
> Note that there are lots of different formulas for this sort of thing, but the one above should represent worst case for my door header because it assumes the beam is simply supported at either end (in reality it has lots of engineering screws holding it in place along some of its length and also has the roof load partially distributed either side of the 'fulcrum' too, which I imagine restricts the movement - not that I know what I am talking about). Oh yeah, please note that I am absolutely NOT qualified in this topic, and everything I say should be considered as science fiction, even the science part is pushing it a bit.
> I will point out though that I am lucky enough to know somebody that does know what he is talking about, and he checked this over for me and helped me with some of the calcs, so it isn't completely worthless. As a minimum I think it gives a good indication of how the options stack up against one another. Worst case its a bit of fun, and a good opportunity for everybody to laugh at my mistakes.
> 
> Variables
> 
> View attachment 117772
> 
> 
> The legend in the pictures explains what the variables are, so I wont double explain those, but it is worth noting that the values for youngs modulus for each material can be found online in the so called 'blue book', as can the values for moment of inertia (which is specific to each shape / cross section) - you can calculate this if you want to, but its easier to look it up. I vaguely remember us covering how to do this in my mech eng degree, but that was 20 years ago and I was rubbish at it then and suspect even crapper now so much prefer standing on the shoulders of giants. Oh yeah, 'w' or roof load is the other funny one. I think for that one I calculated the weight of my entire roof (timber, insulation, EPDM, chipboard) and then added some for static snow load, and finally I think some for dynamic load for people / person (me) walking on there. I also divided the numbers by two because (approx.) half the load is on the front wall and the other half is on the back wall (my side walls do not support any load) Honestly can't remember exactly how I got that number, but as I say all my assumptions are clearly shown in the workings so as not to mislead anybody into how I got the overall deflection results. Looking at these numbers now, we have 14 N/cm which is 1.4kg per cm, which is 140kg per metre - so that 'feels' in the right ball park for the amount of load along that beam.
> Finally, regarding variables, you will notice the slightly hilarious use of 'cm' as a unit. I am advised that the golden rule with SE calcs is to pick one unit and stick with it, and because a lot of the numbers provided for free in the blue book are in 'cm' it makes sense to use cm throughout.
> 
> How I will contextualise the results
> Seeing as I don't know how much deflection is tolerable by the doors, due to the fact it is a secret (not disclosed by the door manufacturers), I need a way to contextualise any numbers that pop out of the calculations. I am clutching at straws a little here, but I did find some rough guidelines that I think could help put the deflection values into context: I understand that some people work the following rule:
> • <2m span = doubled up 2 x 6 timber is ok
> • >2m span = metal beam required (or you could use thicker timber, but you can't simply add in 9x2 headers when you only have 2.5m overall building height to play with - so we end up in metal beam territory once a 6 x 2 isn't strong enough)
> 
> So, I will use a doubled up 6 x 2 timber as a sort of baseline solution that is 'probably' acceptable for a 2 metre span. Considering my span is 2.4m, I know that any alternative designs only need to be say 20% stronger, for the same constrained / max 150mm header thickness. (I think I mentioned this already, but I cannot just simply add thicker timbers and be done with it, due to the 2.5m building height restriction. That in itself is the ONLY reason for doing all this faffing around - I am fixed with 150mm max for my header)
> 
> The results
> I will include some extracts below from my summaries for each of the 4 options so that you can see my assumptions (mistakes) in all their glory. As you can see, the timber option (for my 2.4m wide bifold) gives 3.4mm deflection (in the middle), and the metal options are far stiffer ranging from 0.71mm to 0.34mm deflection.
> 
> View attachment 117773
> 
> 
> View attachment 117774
> 
> 
> View attachment 117775
> 
> 
> View attachment 117776
> 
> 
> Below are the full workings in excel.
> View attachment 117777
> 
> 
> The decision
> So to cut a long story short (oops too late for that) I have decided to use doubled up 6 x 2 timber for above the french doors which have only a 1.6m span, and a flitch beam for above the bifold door which has a 2.4m span.
> 
> Factors influencing the decision:
> COST
> From a cost perspective timber is cheapest (about £50), and all the metal options work out in a similar same ball park, although flitch was cheaper than the other two metal options by about 30 or 40%
> STRENGTH
> Again, all the metal options are basically the same - as a minimum they are 4 times stiffer than timber, and if we work from the assumption that the timber option is good enough for a 2m span, then we can conclude from the numbers that the metal options are all way stronger than needed for my 2.4m. So, for my span, strength is not really a factor when choosing between the metal options.
> WORKABILITY
> the primary reason for choosing flitch beam over i beam or RHS was the fact that the flitch beam gave me a timber surface on both sides, which is nicer to work with (attaching cladding on outside or plasterboard on inside). I dare say flitch beam is slightly more hassle to erect than RHS or I beam because you have to drill holes in the timber and bolt it all together, which takes time, but its probably 2 hours of work to construct and install a flitch beam versus 1 hour to install RHS or I beam so probably not significant in the grand scheme of things.
> 
> Mildly relevant distraction #4: I just checked with future self, and I / he has confirmed that the flitch beam did take about 2 hours, not including the 30 minutes spent staring at it proudly afterwards, or the 15 minutes spent explaining it to my (completely uninterested) wife
> 
> Summary
> Overall I believe flitch beam to be the best option for this application, but I reserve the right to change my mind later, probably when its too late. See below for some top secret pictures which I took from the future.
> 
> View attachment 117778
> 
> 
> View attachment 117780
> 
> 
> Cost wise we are looking at about £100 for the flitch plate, which then gets sandwiched between two timbers to create a flitch beam. Note that the delivery costs for these things are huge (prohibitively so), so I picked mine up in my A-team van as the place was only about 40 minutes away. You will also need some bolts too. And wood. Under £200 'all in' I guess, which feels like good value if it keeps the doors working properly.
> 
> I am sorry for the length of that post, I find it hard to filter and I also find it hard and distinguish between useful and useless information. But, one man's trash is another man's treasure. Maybe that means my garden room could actually be worth something in the future.... :-D
> 
> Martin


Hi Martin,
Fantastic post!! I've been trying to figure out what beam to use in the garden room I'm planning. I've trawled the internet and this is the first time I've seen anything like an explanation that tries to lay out the basic calculations required....So many thanks for that!!

Originally, I had a 2.5m bi-fold chosen and was planning on a 160x80x5 RHS as I know they are widely used for that span, especially by Oakwood Garden Rooms (great videos on YouTube by the way!). Then the wife changed her mind and I'm re-planning for a larger room with a 4m bi-fold. I contacted Liam at Oakwood and asked him if the same RHS but longer would suffice and he advises that he's used it across the same span...but I wanted to check the math/deflection.

That's where I've come a cropper....because trying to figure out the equations is proving VERY confusing.
Your post here really helps...but I do have some questions...

I've tried to follow your calculations and referred to the Blue Book online (https://www.steelforlifebluebook.co.uk/cfrhs/ec3-ukna/section-properties-dimensions-properties/) but can't make the numbers right for your beam dimensions on the RHS option? Can you help? I'm assuming the second moment of area is through the Z-axis? What about the the elasticity variable?...the blue book refers to cm^3 not cm^2 and then your Excel has a N/cm^2 unit of measure?

Also, you don't make it clear in your explanation but presumably you are only using the section of roof supported by the beam as the 'w' variable? How did you account for your weight during a maintenance period....or a snowfall? These are temporary loads so presumably only a portion is used in the calculation?

Another one - I assume you measure the beam length as the "unsupported" span (i.e. not including the sections at each end that are supported by the stud walls)?

Sorry for all the questions - I'm not degree qualified but I like to think my maths is reasonable, so can you help me understand how all the calculations work? Perhaps send me the Excel sheet you worked to?

In simple terms...all I'm looking for is what the deflection would be over a 4m bifold span.

(Yes, I could just employ the services of a SE...but I do like to understand these things myself, if possible - and besides I'm tight as!!).

Many thanks!!


----------



## Molynoox

Churchy00 said:


> Hi Martin,
> Fantastic post!! I've been trying to figure out what beam to use in the garden room I'm planning. I've trawled the internet and this is the first time I've seen anything like an explanation that tries to lay out the basic calculations required....So many thanks for that!!
> 
> Originally, I had a 2.5m bi-fold chosen and was planning on a 160x80x5 RHS as I know they are widely used for that span, especially by Oakwood Garden Rooms (great videos on YouTube by the way!). Then the wife changed her mind and I'm re-planning for a larger room with a 4m bi-fold. I contacted Liam at Oakwood and asked him if the same RHS but longer would suffice and he advises that he's used it across the same span...but I wanted to check the math/deflection.
> 
> That's where I've come a cropper....because trying to figure out the equations is proving VERY confusing.
> Your post here really helps...but I do have some questions...
> 
> I've tried to follow your calculations and referred to the Blue Book online (https://www.steelforlifebluebook.co.uk/cfrhs/ec3-ukna/section-properties-dimensions-properties/) but can't make the numbers right for your beam dimensions on the RHS option? Can you help? I'm assuming the second moment of area is through the Z-axis? What about the the elasticity variable?...the blue book refers to cm^3 not cm^2 and then your Excel has a N/cm^2 unit of measure?
> 
> Also, you don't make it clear in your explanation but presumably you are only using the section of roof supported by the beam as the 'w' variable? How did you account for your weight during a maintenance period....or a snowfall? These are temporary loads so presumably only a portion is used in the calculation?
> 
> Another one - I assume you measure the beam length as the "unsupported" span (i.e. not including the sections at each end that are supported by the stud walls)?
> 
> Sorry for all the questions - I'm not degree qualified but I like to think my maths is reasonable, so can you help me understand how all the calculations work? Perhaps send me the Excel sheet you worked to?
> 
> In simple terms...all I'm looking for is what the deflection would be over a 4m bifold span.
> 
> (Yes, I could just employ the services of a SE...but I do like to understand these things myself, if possible - and besides I'm tight as!!).
> 
> Many thanks!!



Blue Book
I don't know if this helps, but I made some notes when I got into all this thinking I would forget how it was done, below is the page on RHS beam. Elastic modulus is probably supposed to be volume not area, so typo in my excel I suspect. Its been a long while since I looked at this so honestly cant remember 






W variable
I calculated the weight of the roof by multiplying the volume of each component multiplied by the density for each material (EPDM, C24 etc), then I added some dynamic loads such as snow and people to get the total loading. In terms of which part of the roof weight to use, from memory the units were 'per metre', so it all cancelled out. If that makes sense.

Beam length
yes its the unsupported part, the building edges act as two fulcrums at either end, thus defining the span

4m beam
Using my crazy excel sheet the deflection for your 4m beam comes out at 2.6mm (quite a bit different to a 2.4m span surprisingly)

hope that helps anyway.
and by the way I understand your position having done similar research myself, its not so easy to get the answers and I only started doing all this faffing around because I couldn't find a nice off the shelf answer online.

*disclaimer again*: I know nothing.

Martin


----------



## Churchy00

Molynoox said:


> Blue Book
> I don't know if this helps, but I made some notes when I got into all this thinking I would forget how it was done, below is the page on RHS beam. Elastic modulus is probably supposed to be volume not area, so typo in my excel I suspect. Its been a long while since I looked at this so honestly cant remember
> 
> View attachment 136130
> 
> W variable
> I calculated the weight of the roof by multiplying the volume of each component multiplied by the density for each material (EPDM, C24 etc), then I added some dynamic loads such as snow and people to get the total loading. In terms of which part of the roof weight to use, from memory the units were 'per metre', so it all cancelled out. If that makes sense.
> 
> Beam length
> yes its the unsupported part, the building edges act as two fulcrums at either end, thus defining the span
> 
> 4m beam
> Using my crazy excel sheet the deflection for your 4m beam comes out at 2.6mm (quite a bit different to a 2.4m span surprisingly)
> 
> hope that helps anyway.
> and by the way I understand your position having done similar research myself, its not so easy to get the answers and I only started doing all this faffing around because I couldn't find a nice off the shelf answer online.
> 
> *disclaimer again*: I know nothing.
> 
> Martin


Hi Martin,

Thanks again for your reply....it does help...a lot!! Appreciate "you know nothing"!! 

Couple more questions....the Blue Book I found online doesn't have the graduations on beam size that yours appears to....can you send me the link to the Blue Book you are using?

Also, can I ask a favour...I'm kind of OK with with the 2.6mm deflection you have calculated.....at the end of the day the roof will already be constructed before the bi-folds get fitted....so most of the deflection will already be apparent.....and I'm already allowing a 10mm gap for the bifold fitment....so should be OK!! (the bi-folds should still run smoothly...."he says, hoping with everything crossed"!) but....

What would be the deflection on a beam of the same dimensions (160mmx80mm at 4m span - overall beam length 4600mm) but at 6mm thick, not 5mm? I'm hoping the deflection would be less and thus may be a better option.....(please note I'm using 150x47 joists at 400 centres).

Would appreciate your comments....even though you're no expert!!!


----------



## Molynoox

The 2.6 was for 6.3mm thick, it is 3.1mm deflection with 5mm thick steel @ 4m span

blue book link here

note: I have used the roof weight from my building design, which was a 3.7m building depth - your building may be different size and hence roof weight. my joists are same as your though, 150 @ 400 centres.

Martin


----------



## Churchy00

Molynoox said:


> The 2.6 was for 6.3mm thick, it is 3.1mm deflection with 5mm thick steel @ 4m span
> 
> blue book link here
> 
> note: I have used the roof weight from my building design, which was a 3.7m building depth - your building may be different size and hence roof weight. my joists are same as your though, 150 @ 400 centres.
> 
> Martin


That's great mate...thanks. Actually my roof is about the same size. Will take a look at the blue book but think my mind's made up.

Very many thanks for your help. I'm gonna study your follow on posts on the other build elements so expect to be quizzed some more!!

Thanks again!!


----------



## Molynoox

Churchy00 said:


> That's great mate...thanks. Actually my roof is about the same size. Will take a look at the blue book but think my mind's made up.
> 
> Very many thanks for your help. I'm gonna study your follow on posts on the other build elements so expect to be quizzed some more!!
> 
> Thanks again!!


Haha, no problem, feel free to ask if there are other parts of your build you are not sure about, I might have been through the exact same dilemma... I had plenty of those.

Martin


----------



## OldGreyDog

When I was involved in engineering calculations the simple formula for bending moment of a beam carrying a uniformly distributed load was WL/8 (others include point loads at mid-span PL/4 etc.).
Deflection of a beam was calculated to not exceed 1/360th of its span, the formula for simple beams being 5WL³/384EI (where ‘E’ is the modulus of elasticity and ‘I’ the gross moment of inertia of the steel section being tested). I can’t find my steelwork manual now - think I gave it to a mate many moons ago, but its all online now. The linky’ below has tables of available steel sections, most being rolled in different weights to handle different loads. I think there should still be ’safe load charts/tables’ in there for the commonly rolled beam sections - there used to be in my paper version!


https://www.steelconstruction.info/images/6/65/Handbook_of_Structural_Steelwork_EE_55-13.pdf


----------



## BucksDad

@Molynoox enjoyed reading through this thread again last night as I've now decided to switch from SIPs to timber frame after costing it up this week.

What size nails did you use for the framing and what size for the cladding? Did you use the 1st fix Hikoki for the cladding or did you have to get the 2nd fix gun as well?


----------



## Molynoox

If you read it all you deserve a medal 
I used 90mm nails for framing using my hikoki.
I hand nailed the cladding nails, couldn't justify the cost of another nail gun. I bought stainless steel, 50mm nails for that, as recommended by Silva timber. Also face fixed the nails, not secret nailing. Silva recommends face fix also, as do all the cladding companies it seems. I think I tried secret nailing and it just wasn't working. Maybe need a nail gun for that one, and smaller nails. Not sure.

I am wondering if I could have used my hikoki for the cladding....


----------



## Molynoox

Interesting to read that you are switching from SIPS. I am going to be doing another build and I am currently investigating SIPS as the method!

I haven't done the accurate costings yet but my rough estimates are that it is more expensive on materials. But cheaper on time as it goes up faster.

I don't want to complicate your decision making but there is a sort of in between option you might want to consider, I am looking into this, which is buying SIPS panels and cutting them to size yourself.

I think a lot of the cost in SIPS could be the custom design process for the panel layout that is required.

Are you looking at a custom SIPS design or an off the shelf SIPS garden room?

Martin


----------



## BucksDad

It is a custom design which I did and where I specified a number of full panels + the height / widths of cuts in each panel.. no design fee per say however there is a cutting charge of £25 + VAT per panel.

The things I've found are
- Each connection between the panels is 50mm, so to make the timber spline, you're connecting two lots of 50mm timber together - every 1220mm. This is effectively the same as a timber frame with 600mm centres, so even going down to 400mm centres, the cost is not that different in terms of timber. I'd argue the time to construct these and then put them in, including nailing, squirting foam etc. is probably comparable to building out a timber frame - albeit there is then no time then needed for the insulation / OSB.
- The panels are heavy. I don't fancy trying to lift the panels by myself and timber frame gives you the option of a lot of solo work.
- In a SIPS panel, you are paying for insulation + 2 sides of OSB and you still need an internal finish (in my case plywood). Therefore when I compare the cost, with a SIPS panel, I am paying for 2 sides of OSB, insulation + plywood. For timber frame construction, I don't need either layer of OSB - my walls will be as per Mike's shed method - cladding, batten, breather membrane, frame, vapour barrier, plywood, so I am effectively paying for insulation + plywood, removing the cost of OSB
- Constructing timber frame, you can order from a local timber yard and pay minimal delivery (I have a local one 10 mins drive from me who I think charge £20!). For 15 SIPs panels, the delivery charge I was quoted was £350+VAT (£420)
- I wouldn't fancy trying to cut the panels and make the rebates myself, it looks a real pig of a job.

Anyway, the long and short of it is that the quote for the SIPs panels, required timber, cuts and delivery was £3150. I have costed up the timber frame construction and it comes to £1300. For that SIPs cost, I am paying for 30 sheets of OSB I don't need and there is £300 for the cutting and £420 for the delivery.

Although overall construction time will be quicker with SIPs and a bit more thermally efficient, unfortunately I can't justify that price difference - that's a lot of tools I can buy instead 

If you planned to do a double skin of OSB anyway, then the cost difference does reduce a lot and probably makes it more attractive.


----------



## Molynoox

BucksDad said:


> It is a custom design which I did and where I specified a number of full panels + the height / widths of cuts in each panel.. no design fee per say however there is a cutting charge of £25 + VAT per panel.
> 
> The things I've found are
> - Each connection between the panels is 50mm, so to make the timber spline, you're connecting two lots of 50mm timber together - every 1220mm. This is effectively the same as a timber frame with 600mm centres, so even going down to 400mm centres, the cost is not that different in terms of timber. I'd argue the time to construct these and then put them in, including nailing, squirting foam etc. is probably comparable to building out a timber frame - albeit there is then no time then needed for the insulation / OSB.
> - The panels are heavy. I don't fancy trying to lift the panels by myself and timber frame gives you the option of a lot of solo work.
> - In a SIPS panel, you are paying for insulation + 2 sides of OSB and you still need an internal finish (in my case plywood). Therefore when I compare the cost, with a SIPS panel, I am paying for 2 sides of OSB, insulation + plywood. For timber frame construction, I don't need either layer of OSB - my walls will be as per Mike's shed method - cladding, batten, breather membrane, frame, vapour barrier, plywood, so I am effectively paying for insulation + plywood, removing the cost of OSB
> - Constructing timber frame, you can order from a local timber yard and pay minimal delivery (I have a local one 10 mins drive from me who I think charge £20!). For 15 SIPs panels, the delivery charge I was quoted was £350+VAT (£420)
> - I wouldn't fancy trying to cut the panels and make the rebates myself, it looks a real pig of a job.
> 
> Anyway, the long and short of it is that the quote for the SIPs panels, required timber, cuts and delivery was £3150. I have costed up the timber frame construction and it comes to £1300. For that SIPs cost, I am paying for 30 sheets of OSB I don't need and there is £300 for the cutting and £420 for the delivery.
> 
> Although overall construction time will be quicker with SIPs and a bit more thermally efficient, unfortunately I can't justify that price difference - that's a lot of tools I can buy instead
> 
> If you planned to do a double skin of OSB anyway, then the cost difference does reduce a lot and probably makes it more attractive.


Lovely summary  
Lots of great food for thought in that post. As I am investigating SIPS at the moment this information is excellent timing for me.

On the splines, some of the systems don't use timbers to connect, they use instead a sort of mini SIP panel. I wonder if those are cheaper than a timber spline, and also quicker to fit than two timbers back to back?

One aspect that I'm currently investigating about SIPS is electrical first fix, I think this could offer an advantage over timber framing because you don't need to drill through any timbers to get the cable runs, could be an efficiency gain. Also other things like the OSB on interior surface, underneath plasterboard could be handy for hanging heaters, TV etc.

Just thoughts at this stage as I'm just starting my journey learning about these but I think there could be done nice efficiencies with SIPS when considering the full package. And also some downsides of course.

I am going to end up with a sort of comparison matrix between timber framing and SIPS when I'm done looking at this. I wonder if it would be worth me posting that here or doing a separate thread about it even.... Yet more knowledge that seems wasted on one person / one build 

Martin


----------



## HOJ

Molynoox said:


> you don't need to drill through any timbers to get the cable runs


We don't.

In a "residential" construction, same as with a stick build , when using SIPS you would/should create an internal service void for electrics/plumbing, on the inboard side of a vapour membrane.


----------



## Molynoox

HOJ said:


> We don't.
> 
> In a "residential" construction, same as with a stick build , when using SIPS you would/should create an internal service void for electrics/plumbing, on the inboard side of a vapour membrane.


Yup. I've got that far in my research, I think this is quite a tidy solution. You can simply put up two battens per vertical so you create a gap for the cable runs through the middle of both battens.

One thing that I was curious about is the strength of the joint between batten and SIPS panel, particularly on the ceiling, with plasterboard hanging off it. Presumably screwing into the OSB on face of SIP is strong enough? What screws are used are they specialist ones?

Martin


----------



## HOJ

Molynoox said:


> You can simply put up two battens per vertical so you create a gap for the cable runs through the middle of both battens.


We set ours at 600mm centers for the plasterboard gauge, unless we need something specific, but also block round any switch/socket outlets that are in isolation.



Molynoox said:


> Presumably screwing into the OSB on face of SIP is strong enough? What screws are used are they specialist ones?


1st fix Ring nails, @ 300mm spacing, length to suit batten thickness + 25mm (typically 50mm) or good quality screws, were its awkward to get to.

This is one I'm "helping" out on, this is awkward to do..


----------



## Molynoox

why do you need block around sockets? and by that do you mean create a ring of batten behind the PB, around the perimeter of socket?


----------



## Molynoox

I wonder what the pull out force is on a 50mm ring shank nail when it's going into only 12mm of OSB?
It doesn't feel like it would be strong enough to support plasterboards on a ceiling - I was worried about screws not being good enough but you are saying that ring shank nails are ok!


----------



## HOJ

Molynoox said:


> create a ring of batten behind the PB, around the perimeter of socket?


Precisely, a lot of spark's prefer to use metal back boxes rather than the plaster board plastic ones, so we end up fitting pieces of batten round the perimeter of the boxes to stop the face plates pulling the plasterboard back , the better option would be to get the beggars for the money they charge, to pack the box out or use a deeper box in the first place, its a problem with attitude, happens all the time , trades don't think about the follow on.



Molynoox said:


> pull out force is on a 50mm ring shank nail when it's going into only 12mm of OSB?


The nails aren't working in isolation, you could look at how_ a_ screw could hold up plaster board in the same way, we consider the circumstance and fix accordingly (be it more nails, screws, glue if appropriate)


----------



## Molynoox

HOJ said:


> Precisely, a lot of spark's prefer to use metal back boxes rather than the plaster board plastic ones, so we end up fitting pieces of batten round the perimeter of the boxes to stop the face plates pulling the plasterboard back , the better option would be to get the beggars for the money they charge, to pack the box out or use a deeper box in the first place, its a problem with attitude, happens all the time , trades don't think about the follow on.
> 
> 
> The nails aren't working in isolation, you could look at how_ a_ screw could hold up plaster board in the same way, we consider the circumstance and fix accordingly (be it more nails, screws, glue if appropriate)


Ok thanks.
Sorry for more questions, just curious, but do you excavate a rebate into the sips panel for the electrical back boxes? I can't imagine 25mm is enough for the back box.

When you say the nail isn't working in isolation... it is in my head! The nail goes through batten and into the sip panel in the ceiling. The PB is fastened to the batten. Therefore the nails are the only thing holding up the PB to the SIP. Or do your plasterboard screws go into OSB also?

Martin


----------



## HOJ

Molynoox said:


> excavate a rebate into the sips panel for the electrical back boxes?


You can't dig a hole in the SIPS without compromising its integrity and that of the vapour membrane. Be better if the sparks used 35mm deep boxes it wouldn't be an issue, it would end up be fairly flush to the PB front face, (25mm batten + 12.5 PB) my problem is I get in to the job after they've 1st fixed, and have to work round, using the principal of the 7P's would be good! on a lot of projects I go to.


Molynoox said:


> When you say the nail isn't working in isolation... it is in my head!



You keep saying "the nail" we use thousands on a job, (I buy boxes of 2500 in a box) what I mean in isolation, is, 1 nail & I can pull it out, not easily though, 10 and I'm in for a major battle, over shoot on PB screw length also adds to fixing, but not relied upon.

I didn't mean to hijack you excellent thread, its only since SIPS has come up, maybe wait till you've done your "comparison matrix between timber framing and SIPS", we could pick up again 

SIPS is more expensive than stick, but 55% quicker to build, the one I'm "helping" out on, took 2 weeks to water tight ish!

Paul


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## Molynoox

HOJ said:


> You can't dig a hole in the SIPS without compromising its integrity and that of the vapour membrane. Be better if the sparks used 35mm deep boxes it wouldn't be an issue, it would end up be fairly flush to the PB front face, (25mm batten + 12.5 PB) my problem is I get in to the job after they've 1st fixed, and have to work round, using the principal of the 7P's would be good! on a lot of projects I go to.
> 
> 
> You keep saying "the nail" we use thousands on a job, (I buy boxes of 2500 in a box) what I mean in isolation, is, 1 nail & I can pull it out, not easily though, 10 and I'm in for a major battle, over shoot on PB screw length also adds to fixing, but not relied upon.
> 
> I didn't mean to hijack you excellent thread, its only since SIPS has come up, maybe wait till you've done your "comparison matrix between timber framing and SIPS", we could pick up again
> 
> SIPS is more expensive than stick, but 55% quicker to build, the one I'm "helping" out on, took 2 weeks to water tight ish!
> 
> Paul


Yes you are right we are getting off topic, and it's my fault, but I'm so keen to pick your brains 
I am definitely going to start a fresh thread on this so it would be good to get your views in there.

Oh yeah, regarding the nails I know there is more than one, I'm just not explaining myself well, but I understand your point now anyway im still surprised though 

I like your last paragraph, that's exactly where I am with my thinking at the moment... time is money, and I think I am starting to understand the popularity of sips now.

Martin


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## Scruples

Molynoox said:


> Lovely summary
> Lots of great food for thought in that post. As I am investigating SIPS at the moment this information is excellent timing for me.
> 
> On the splines, some of the systems don't use timbers to connect, they use instead a sort of mini SIP panel. I wonder if those are cheaper than a timber spline, and also quicker to fit than two timbers back to back?
> 
> One aspect that I'm currently investigating about SIPS is electrical first fix, I think this could offer an advantage over timber framing because you don't need to drill through any timbers to get the cable runs, could be an efficiency gain. Also other things like the OSB on interior surface, underneath plasterboard could be handy for hanging heaters, TV etc.
> 
> Just thoughts at this stage as I'm just starting my journey learning about these but I think there could be done nice efficiencies with SIPS when considering the full package. And also some downsides of course.
> 
> I am going to end up with a sort of comparison matrix between timber framing and SIPS when I'm done looking at this. I wonder if it would be worth me posting that here or doing a separate thread about it even.... Yet more knowledge that seems wasted on one person / one build
> 
> Martin


When I built my workshop, I considered the different methods of wiring it and ended up using 100mm plastic trunking around the whole inside of building. I've never regretted it. It's easy to add/move sockets giving me a flexibility that I wouldn't have had by recessed cabling. I used a segregated trunking as I wanted to run some ethernet cables.


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## BucksDad

Indeed @Scruples, I'm doing the same but @Molynoox is building garden rooms so won't be wanting his utilities surface mounted.

@Molynoox I would start a separate thread for the SIPs discussion.


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## BucksDad

@Molynoox Do you notice the fixings on your fascias on the garden room? When I see pictures or videos on YT, they look really obvious and spoil the look somewhat, wouldn't mind a fixture-free fascia.. do you notice it day to day?


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## Molynoox

Hi


BucksDad said:


> @Molynoox Do you notice the fixings on your fascias on the garden room? When I see pictures or videos on YT, they look really obvious and spoil the look somewhat, wouldn't mind a fixture-free fascia.. do you notice it day to day?


Yes it's my one annoyance with the build. Ive always hated those little bullets sticking out of the front of the fascias. I spent a bit of time looking for an alternative when I was building mine but didn't find anything in time for when I needed it.

I really wanted powder coated aluminium or something like that, a nice clean finish. I've seen it on some builds but it's quite rare. I couldn't find any suppliers for it at the time and i sort of gave up.

The aluminium trim is quite popular with some of the sips builders if they are using those Kingspan roof panels, and it looks good from the front but not from the top IMO. So I would still want to use EPDM (and not Kingspan panel) but with Alu trim instead the plastic ones.

You will see on my build that I managed to have just one set of visible bullets by hiding the fascia fixings (using normal nails) under the roof trim fixings (the roof trim fixings are those plastic capped nails that you can see).

So I am keen to find a solution for that one. It would probably need to be a roof trim underneath to direct water off the EPDM roof, and the alu trims on top. The roof trims are not as deep as the roof thickness therefore it would probably require an additional board to act as a packer sitting below the roof trim. With the roof trim and packer board side by side (or top to bottom I suppose) this would give a flat surface for the alu trim to mate up to on the fascia.

Martin


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## BucksDad

I was wondering about doing a double fascia... do the roof trim and fascia as per normal, then put another fascia on top which is taller and hides the roof trim. Glue some bits of wood every 400mm to the fascia with CT1 and then use buttonfix with the wood spacers to give a fixture-free external fascia


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## Molynoox

BucksDad said:


> I was wondering about doing a double fascia... do the roof trim and fascia as per normal, then put another fascia on top which is taller and hides the roof trim. Glue some bits of wood every 400mm to the fascia with CT1 and then use buttonfix with the wood spacers to give a fixture-free external fascia


that's a brilliant idea.
I think you could miss out the first fascia board too, and then its the exact same materials as a conventional build other than the extra wooden packers and the buttons. I'm going to model that up to get my head around it.
Martin


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## BucksDad

My only concern with skipping the first fascia board is you will have a small gap that rain can fall through and potentially get the exposed wood wet


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## Molynoox

*Jul 2022 - Workshop interior*

I figured I would do an update seeing as I have started work on the interior of the workshop and also the garden is looking more mature now so I thought I would put up some updated pictures.

I did a thread about having grey walls in a workshop and the conclusion was that it would be too dark, so I compromised and painting one wall anthracite and the rest white. I think it worked out well and I am glad I asked for advice.

Excuse the mess:


















its already starting to feel like a nice space to work in and I'm looking forward to getting it finished and usable. I'm struggling to find time/energy to finish it off at the moment, which is a little frustrating as I am feeling quite unorganised with all my tools and stuff floating around in random plastic boxes.

The next stage (after finishing the skirting boards) is to build a workbench and storage for tools. Not sure on the best sequence for that:
1. workbench then storage.... could use the workbench to build the storage
2. storage then workbench... would be more organised with my tools which would help me build the workbench faster
 

_Updated pictures of the garden + garden room:_














As you can see I have some grass now, and the plants are growing really fast making the garden look miles better than it was at the start of the summer. And I'm now a convert to growing plants in pots rather than in the ground - this is the first time I've had a garden without thousands of weeds everywhere - its quite a novelty 

obligatory nightime shot:





Hopefully I can share some progress on the actual workshop soon - this is a woodworking forum after all!

Martin


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## Keefy.

How you can possible expect to work in that environment is beyond me! 

I know it's a bit of a jaunt from Billericay but we're going to put one up in Birmingham. Only a simpleish Oakwood affair but if you fancy a week or so your help would be most welcome.

Seriously, really nice work.
Personally I'd go for bench first then storage. You may find in practice the storage might be in the way.
Again, nice!


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## Molynoox

Keefy. said:


> How you can possible expect to work in that environment is beyond me!
> 
> I know it's a bit of a jaunt from Billericay but we're going to put one up in Birmingham. Only a simpleish Oakwood affair but if you fancy a week or so your help would be most welcome.
> 
> Seriously, really nice work.
> Personally I'd go for bench first then storage. You may find in practice the storage might be in the way.
> Again, nice!


Haha thank you so much for the kind words 
If I was closer I would be happy to help but as you say that's quite a commute! 
If you plan to do a build thread I will keep a look out for it as I would be happy to offer any help I can.

Martin


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