# Shed build, many many questions...



## Torx

Following on from this thread (thanks for the contributions), I've realised I'll be asking question after question so have decided to put it all together in one and hopefully document the build.

This is the first of two outbuildings I'm hoping to build in the garden, this one is basically a posh shed, a practise run for the second larger one which will be part home office / part summer house. 

(Actually, I might need to temporarily partition part of this first one for a small office space if push comes to shove, so all the more reason to insulate it as suggested.)

I'm basing it around four 8' x 4' sheets, as it's convenient and it's roughly the right size for the space I've allocated for it. 

The roof will be pent to keep things simple.

I've put a gully in just behind it, probably completely unnecessary but it was near enough to existing drainage that it was simple to do, and the pipe needs to run behind it to the larger building I have planned so I needed to get it in before I built this.

This is the base design (so far), using 2" x 4" pressure treated C24 timber with joist hangers where unsupported. I'll insulate it with used Kingspan / Celotex or whatever's cheapest, with 18mm exterior ply on top. 





How deep do I need to dig / fill under the high-density concrete blocks with MOT type 1? I have a 6 year old who loves digging so free labour - no need to cut corners here. I was thinking I'd dig to about 350mm from ground level and fill/compact to 300mm. The ground is clay, rock solid. The adjacent garage has a 100mm slab put down by cowboys 25 years ago and hasn't moved (at least not noticeably) .

How do I work out how much hardcore I'll need? Will 1 tonne be enough?

Do I need mortar between hardcore and block?

The remaining 50mm I'd fill with loose gravel that I've got hanging around.

Some sort of weed membrane too maybe?

That leaves me with a 50mm gap underneath for foxes / badgers etc., to make their homes.






For the walls I had this in mind using 2 x 4" again (is treated necessary?) to allow for possible insulation in future or in the partitioned area if I decide to do that:






Are 19mm battens OK for between the cladding and OSB or am I better with 25mm to allow a bigger air gap and longer screws / nails for the cladding?

No clue how to work out roof pitch, this (about 4.5°) looks about right....





Oh yeah, permitted development. The red line is 6ft, and I'm 5.10. 

For the roof material either a double layer of felt, or perhaps this stuff:







I think buying fancy windows would be pushing the budget, is there any reason I can't make simple non-opening softwood frames with double glazing panels only? Just buy the double glazed panels?

A quote for a similar building from a posh shed supplier (I've seen their stuff, it is good), came to £3800, so the plan is do better than that for a similar price...


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## mikej460

The foundations are largely dependent on the ground conditions e.g. any tree roots, water logging, clay? The normal rule of thumb is 100 - 200mm hardcore then concrete footings (if you have ruled out a concrete slab) then block or brick with a dpc.

My understanding is that the stud wall plan is incorrect, you need the OSB3 on the inside workshop stud work with insulation between the studs then breathable membrane on the outside of the studs then a venting gap created by battens then cladding. The principle being that warm, damp air moves out towards colder outside air and is carried away by vented space created by the battens, the OSB3 acts as a vapour barrier to stop any escaping into the building.


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## John Brown

Check out eBay or Facebook marketplace for Windows. I bought two oak framed double glazed units for £14.50, which I incorporated into my build.
I did give the builders a fiver to help me lift the larger one on to my roof rack, but still a total bargain.

As for overall cost, my 4.5m by 3m shed, with insulation and waney edge larch cladding, cost me the better part of £5k, and that was 2 years ago. I estimate timber is a good 50% dearer now, if not more.


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## Jameshow

I'd increase the floor beams to 6" deep and miss out the centre blocks and the doubled up timbers save a bit in costs and effort? 

6" will easily span 8ft unless you 25st!


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## Torx

mikej460 said:


> The foundations are largely dependent on the ground conditions e.g. any tree roots, water logging, clay? The normal rule of thumb is 100 - 200mm hardcore then concrete footings (if you have ruled out a concrete slab) then block or brick with a dpc.
> 
> My understanding is that the stud wall plan is incorrect, you need the OSB3 on the inside workshop stud work with insulation between the studs then breathable membrane on the outside of the studs then a venting gap created by battens then cladding. The principle being that warm, damp air moves out towards colder outside air and is carried away by vented space created by the battens, the OSB3 acts as a vapour barrier to stop any escaping into the building.



No roots etc., nearby. 

That's a pest about the OSB, I wasn't planning to insulate the walls yet. Any detriment to put it on the outside?




John Brown said:


> Check out eBay or Facebook marketplace for Windows. I bought two oak framed double glazed units for £14.50, which I incorporated into my build.
> I did give the builders a fiver to help me lift the larger one on to my roof rack, but still a total bargain.
> 
> As for overall cost, my 4.5m by 3m shed, with insulation and waney edge larch cladding, cost me the better part of £5k, and that was 2 years ago. I estimate timber is a good 50% dearer now, if not more.



Good plan, I'll do that. I do actually have one small mahogany DG window I could somehow incorporate.



Jameshow said:


> I'd increase the floor beams to 6" deep and miss out the centre blocks and the doubled up timbers save a bit in costs and effort?
> 
> 6" will easily span 8ft unless you 25st!



I'm trying to save every inch of height within my allotted 2.5m. Is that mad?


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## John Brown

I used rockwool insulation in the walls, and Celotex/Kingspan in floor and pitched roof. OSB inside, Tyvek outside. Even though I don't have heating, I've so far had zero condensation or rust problems.


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## Torx

I was copying Colin to be honest, though I thought the water barrier might be better done with something breathable.


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## Fitzroy

Repurposed windows off gumtree or similar is the cheapest option for definite, just depends on if you can work them into your design. If you build from cheap softwood you’ll need to paint. I built from Doug Fir which is supposedly semi durable, hence not painting. If found no need to open mine in the last 5 years. 

OSB outside is great for the build as it goes up quick, however it is suboptimal from a condensation risk perspective. But if you go OSB inside insulating at a later date is slightly harder as you’ll have to remove it and replace. Perhaps not an issue if you screwed not nailed. At some point I will insulate mine ans I run the risk of interstitial condensation. However it’s not in constant use so I’m happy it’s a low risk. 

Roof height was an issue for my build, so I decided to apply for planning permission. Cost a few hundred quid and a few hours for drawings but council were super helpful and I could build what I wanted. I live in a conservation area also!

I’d look at EPDM for the roof, it’s easy to use and worked out cheaper than other products on my calculations. 

If you choose to OSB the outside 18mm battens probs ok as OSB also give some attachment depth, if you osb inside I think you’ll want 25mm. 

My build was impacted by protected trees and I could not dig down more than 10cm due to root damage or something. Hence my shallow mot pockets, didn’t research beyond this.

Many of your decisions will be compromises between ‘by the book’ and cost/time to achieve. History will judge how successful your decisions were, but remember it’s a shed not a permanently occupied building providing a safe, warm, dry space for people. 

Fitz


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## mikej460

Torx said:


> That's a pest about the OSB, I wasn't planning to insulate the walls yet. Any detriment to put it on the outside?


If I were you I would install the osb3 on the inside and insulate with rockwool then put the membrane on. The membrane will keep the shed dry until you can get the cladding.


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## Torx

mikej460 said:


> If I were you I would install the osb3 on the inside and insulate with rockwool then put the membrane on. The membrane will keep the shed dry until you can get the cladding.


I didn’t realise the membrane (Tyvek type stuff you mean?) was that effective.


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## Torx

Is there any point in putting a membrane in without insulation, or in readiness for insulating at a later date?


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## Jones

You should remove the topsoil under the blocks but don't need to go deeper than that, you'll find mortar under the blocks means you can level them easily.
All the joists need to be supported mid span unless they can do the whole span, a half brick will do but they need something.
If you build floor first then walls on top I would paint the board edges with bitumen paint,it's a real pain to replace rotted pieces with that build method.
Tyvek or similar will waterproof the shed but only the more expensive UV resistant stuff can be left uncovered for long.
Second hand windows and doors are often on Freecycle etc which will save cash.
Don't waste money on joist hangers, as you can get round to get nails in they're not needed, two 100mm galvanized nails into each joist is plenty strong enough.
You could build the studs tyvek the outside and just nail on bracing on the inside to prevent racking then insulate and board at a later date


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## mikej460

Torx said:


> I didn’t realise the membrane (Tyvek type stuff you mean?) was that effective.


Yes it keeps rain out of the building but also lets water vapour (condensation) out


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## Torx

Jones said:


> You should remove the topsoil under the blocks but don't need to go deeper than that, you'll find mortar under the blocks means you can level them easily.
> All the joists need to be supported mid span unless they can do the whole span, a half brick will do but they need something.
> If you build floor first then walls on top I would paint the board edges with bitumen paint,it's a real pain to replace rotted pieces with that build method.
> Tyvek or similar will waterproof the shed but only the more expensive UV resistant stuff can be left uncovered for long.
> Second hand windows and doors are often on Freecycle etc which will save cash.
> Don't waste money on joist hangers, as you can get round to get nails in they're not needed, two 100mm galvanized nails into each joist is plenty strong enough.
> You could build the studs tyvek the outside and just nail on bracing on the inside to prevent racking then insulate and board at a later date



Thanks. On the soil front, it’s clay, there is literally no top soil it’s just slightly looser on the top as I dug it over and rotorvated years ago before grassing. I’ve heard mixed opinions from ‘ooooh, that’ll sink you’d need a 200mm deep reinforced concrete slab’ to ‘that’s rock solid, plonk anything on top.’ I have to choose the right time to dig or it’s really hard work. 

In the summer cm wide cracks appear in any ungrassed areas.

Here’s some photos from when I put a drain in:










I was planning to buy a tonne of MOT1 and divide it up amongst the 15 blocks which I think would make them about 15cm deep.

But as mentioned, the shoddy garage hasn’t sunk and I do have a habit of overdoing stuff.


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## mikej460

If I were you I'd hire a mini digger, one of the smallest ones that can fit through doorways should be enough. Much easier and more fun!


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## Spectric

With this design, once you have the base in place use wire mesh of some sort to seal all the edges to prevent rodents living underneath, mesh size will determine who can get in!


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## Torx

mikej460 said:


> If I were you I'd hire a mini digger, one of the smallest ones that can fit through doorways should be enough. Much easier and more fun!



Already got one:









Spectric said:


> With this design, once you have the base in place use wire mesh of some sort to seal all the edges to prevent rodents living underneath, mesh size will determine who can get in!



Good plan!


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## Torx

Apparently there are 87 types of MOT Type 1.... 






Search results for: 'mot type 1'







www.huwsgray.co.uk





Does it matter? Hoping to get some delivered for next week so I'll need to order it tomorrow.


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## Valhalla

Torx said:


> Apparently there are 87 types of MOT Type 1....
> 
> 
> 
> 
> 
> 
> Search results for: 'mot type 1'
> 
> 
> 
> 
> 
> 
> 
> www.huwsgray.co.uk
> 
> 
> 
> 
> 
> Does it matter? Hoping to get some delivered for next week so I'll need to order it tomorrow.


Call me old fashioned, but I would build like Mr Chickadee......totally environment friendly

I am intending to build a workshop using similar methods to support the structure. If you decided to remove the structure in the future all you would have left are fillable holes in the ground......


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## stimuli

Hi Torx. In researching my own upcoming build, I've stumbled on this thread, and would like to share some of what I've put together. Please take it with a heap of salt, as I've likely forgotten more than I've learnt over this past year. And do ignore my advice where it conflicts with that of people more credentialed (I have practically none, so the bar is low).

OSB3 on the exterior as sheathing should be fine, provided you take steps elsewhere to reduce condensation risk; most OSB3 is at least a little vapour permeable, albeit much less than OSB2, etc. The main cause of condensation risk will be airtightness and vapour permeability of the building envelope, including the fitting of the insulation. Most often, insulation isn't fit - or foamed - tight to the frame. The gaps left, big or small, allow air and water vapour to exit the enclosure, and can cause condensation on the interior faces of external sheathing, which can cause damp problems you won't find until it's too late. It's especially a problem in roofs, I think due to mistakes or compromises in the buildup.

As noted by others here, a vapour barrier (VCL or vapour control layer) should go on the warm side of the insulation. Something to consider for your posh shed, and particularly for your garden office: You won't need to increase your buildings ability to transmit vapour to the outside (such as by sheathing the interior only), if you put adequate controls in place to reduce the transmission of vapour from the interior through the envelope. A plastic vapour barrier can be fitted to the floor, wall, and ceiling, and taped at the joints and openings using an appropriate tape. Provided your door and window openings are weather sealed, this can greatly decrease the transmission of vapour/ condensation from the interior to the exterior. Something people often neglect is that any openings made in the vapour barrier - such as for electrics - need to be sealed properly. I don't recall how much moisture can be exchanged through holes made for downlighters, sockets, etc. but I remember it was alarming.

Another thing to consider is the cold bridging that could occur on the interior faces, where the timber frame meets the interior sheathing. This is when heat from the interior escapes quicker at points where the frame is in contact with the interior surfaces, and creates a cold spot where condensation can form on the interior. It happens most where many timbers are sandwiched together, or in corners that aren't insulated. One common way to overcome this is to use insulated plasterboard to sheathe the interior, or thin PIR insulation underneath sheets of plasterboard, where cheaper.

The purpose of some of the advice in this thread seems to be to reduce the risk of interstitial condensation, which is important for the longevity of your build. But, I'd say it's also important to look at vapour control more broadly, and find ways to stop it getting into the building fabric in the first place. Unfortunately, most of the stuff I've mentioned will inevitably add to cost, but should also improve the performance of your building.

Hopefully I've not bludgeoned you with my essay. Good luck with your build!

PS Yes to the weed membrane. Pin it down with plastic pegs.


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## Lazurus

EPDM over 19mm osb for the roof, easy to do, very long lasting and competitive pricing against other materials. I did 40m2 myself in a day, all in including tools and adhesives £1200


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## Torx

stimuli said:


> Hi Torx. In researching my own upcoming build, I've stumbled on this thread, and would like to share some of what I've put together. Please take it with a heap of salt, as I've likely forgotten more than I've learnt over this past year. And do ignore my advice where it conflicts with that of people more credentialed (I have practically none, so the bar is low).
> 
> OSB3 on the exterior as sheathing should be fine, provided you take steps elsewhere to reduce condensation risk; most OSB3 is at least a little vapour permeable, albeit much less than OSB2, etc. The main cause of condensation risk will be airtightness and vapour permeability of the building envelope, including the fitting of the insulation. Most often, insulation isn't fit - or foamed - tight to the frame. The gaps left, big or small, allow air and water vapour to exit the enclosure, and can cause condensation on the interior faces of external sheathing, which can cause damp problems you won't find until it's too late. It's especially a problem in roofs, I think due to mistakes or compromises in the buildup.
> 
> As noted by others here, a vapour barrier (VCL or vapour control layer) should go on the warm side of the insulation. Something to consider for your posh shed, and particularly for your garden office: You won't need to increase your buildings ability to transmit vapour to the outside (such as by sheathing the interior only), if you put adequate controls in place to reduce the transmission of vapour from the interior through the envelope. A plastic vapour barrier can be fitted to the floor, wall, and ceiling, and taped at the joints and openings using an appropriate tape. Provided your door and window openings are weather sealed, this can greatly decrease the transmission of vapour/ condensation from the interior to the exterior. Something people often neglect is that any openings made in the vapour barrier - such as for electrics - need to be sealed properly. I don't recall how much moisture can be exchanged through holes made for downlighters, sockets, etc. but I remember it was alarming.
> 
> Another thing to consider is the cold bridging that could occur on the interior faces, where the timber frame meets the interior sheathing. This is when heat from the interior escapes quicker at points where the frame is in contact with the interior surfaces, and creates a cold spot where condensation can form on the interior. It happens most where many timbers are sandwiched together, or in corners that aren't insulated. One common way to overcome this is to use insulated plasterboard to sheathe the interior, or thin PIR insulation underneath sheets of plasterboard, where cheaper.
> 
> The purpose of some of the advice in this thread seems to be to reduce the risk of interstitial condensation, which is important for the longevity of your build. But, I'd say it's also important to look at vapour control more broadly, and find ways to stop it getting into the building fabric in the first place. Unfortunately, most of the stuff I've mentioned will inevitably add to cost, but should also improve the performance of your building.
> 
> Hopefully I've not bludgeoned you with my essay. Good luck with your build!
> 
> PS Yes to the weed membrane. Pin it down with plastic pegs.



Thanks, good info. It does seem a little like the more thermally efficient a building is the more there is to go wrong! I’ve hear of problems with SIPs simply because the building end up too well sealed. Actually I’m curious what sort of OSB SIPs are made from.


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## Torx

Site cleared






Laying out






Positioned the blocks roughly 






Scraped the grass away with a hoe to mark the holes out






I did start digging but forgot to photograph.


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## Torx

Been on holiday so not much time for this but nearly there with the ‘groundwork’s’.

Is there any advantage to having a block set 50mm deep in hardcore with a second block on top (mortar between) or just sit one block straight on top of the hardcore with sharp sand?

Thanks


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## Jameshow

Torx said:


> Been on holiday so not much time for this but nearly there with the ‘groundwork’s’.
> 
> Is there any advantage to having a block set 50mm deep in hardcore with a second block on top (mortar between) or just sit one block straight on top of the hardcore with sharp sand?
> 
> Thanks


What about blocks set in mortar on top of the hardcore the block is then stuck the top layer of hardcore and isn't going anywhere. 

Make it a strong but fairly runny mix so it runs though much of the hardcore??


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## PDW125

Torx said:


> Is there any advantage to having a block set 50mm deep in hardcore with a second block on top (mortar between) or just sit one block straight on top of the hardcore with sharp sand?



6:1 sharp sand and cement dry mix will absorb moisture from the ground and set nicely to stop them moving. Easy to level too and will allow you to move things about


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## fiveforty

Torx said:


> Been on holiday so not much time for this but nearly there with the ‘groundwork’s’.
> 
> Is there any advantage to having a block set 50mm deep in hardcore with a second block on top (mortar between) or just sit one block straight on top of the hardcore with sharp sand?
> 
> Thanks


Sharp sand on its own will eventually wash through the hardcore, as PDW125 says a 6:1 sand/cement mix


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## Torx

PDW125 said:


> 6:1 sharp sand and cement dry mix will absorb moisture from the ground and set nicely to stop them moving. Easy to level too and will allow you to move things about


I like this plan, time to level everything before it goes off!


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## mancmc

For the shed bearers or floor framework, I would use composite timbers say 100 x 50mm section.
Therefore, no timber, tantalised or otherwise in contact with the ground block.
More expensive at the moment but you will get the longevity. Tantalised timbers are not as good as say 20 years ago!


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## Torx

A small amount of progress, due to work commitments and other stuff, base blocks there now and timber on order for the floor.











I’m thinking of getting a length of that recycled decking plastic and using it in place of dpc on top of the blocks just to raise the height a little. 

Found some 90mm celotex insulation at £48 / sheet delivered.


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## Jameshow

Torx said:


> A small amount of progress, due to work commitments and other stuff, base blocks there now and timber on order for the floor.
> 
> View attachment 139684
> 
> 
> View attachment 139685
> 
> 
> I’m thinking of getting a length of that recycled decking plastic and using it in place of dpc on top of the blocks just to raise the height a little.
> 
> Found some 90mm celotex insulation at £48 / sheet delivered.


Good idea on the decking plastic!


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## Torx

Some progress






I decided to use joist hangers in the end as I don’t trust my nailing. 

Apparently this is what you get at £50 per sheet these days






I didn’t fancy an OSB floor but I’ll use it for the walls. 

Just loosely in place here as the insulation is coming tomorrow. 






No need to raise the floor any higher as there’s plenty of air under there.

So whatever gets built on top now at least I’ve got a really solid base and floor.

Picking up a brand new alu window at the weekend which someone’s customer had rejected for a garden room.


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## Torx

Insulation in






Also picked up a massive 2100 x 600mm UPVC window with toughened double glazing for £140. This will be nice if I ever use it for any work rather than storage as a bench will go nicely in front of it. 

Are 2 x 3s adequate for the wall framing? Spacing? Have read up a little on the process of framing the windows. Not sure what I’m doing for a door yet.


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## Torx

I’ve been giving some thought to just building the walls with SIPs. I haven’t worked it out properly but I think I’d need around 12 and I can’t imagine it would work out much more expensive than the materials to frame the walls, unless I decide the insulation isn’t worth the bother. Not sure about using them for the roof but insulated roofing panels would be an option, the minimum pitch is 4 deg.


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## Jameshow

Torx said:


> I’ve been giving some thought to just building the walls with SIPs. I haven’t worked it out properly but I think I’d need around 12 and I can’t imagine it would work out much more expensive than the materials to frame the walls, unless I decide the insulation isn’t worth the bother. Not sure about using them for the roof but insulated roofing panels would be an option, the minimum pitch is 4 deg.


If going for sip for the walls why not for the roof? 

I don't understanding mixing methods??


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## Torx

Jameshow said:


> If going for sip for the walls why not for the roof?
> 
> I don't understanding mixing methods??



I (personally) wouldn’t trust them for anything other than a light duty floor, and if used for the roof it still needs to be covered, whereas the profiled roofing sheets are ready to go.


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## Jameshow

Torx said:


> I (personally) wouldn’t trust them for anything other than a light duty floor, and if used for the roof it still needs to be covered, whereas the profiled roofing sheets are ready to go.


Agreed metal sheet would be best esp if insulated. 

Otherwise I was thinking a cut roof on top of sips dosent make sense. 

I think they would be fine for a roof. 

I'd be more concerned with a floor as the foam could possibly compress under weight of a operator and machine tool??


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## Torx

Stud layout...2 x 4s again - overkill? Probably.


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## Spectric

Did you bitumen the underside of your ply, it will make it last a lot longer and don't forget the edges.


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## Torx

Spectric said:


> Did you bitumen the underside of your ply, it will make it last a lot longer and don't forget the edges.


I didn’t - haven’t heard of that before - sounds like a sticky job! I will fold some DPC over the edges though.


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## Spectric

Torx said:


> I didn’t - haven’t heard of that before - sounds like a sticky job!


Yes it is a job that once done you just bin the brushes and the gloves as it is not worth trying to clean them. The bitumen basically turns ply into a waterproof material, two coats and forget. The ply on my shed sat in a recess on the wooden frame so I bitumed the bottom side of the ply and the edges, then sat it into my frame which was also fully bitumed and then painted the top face and filled the edge void so no chance of water ingress. I just used lino as the floor covering. It is the edges of ply that must not get wet because that starts the ply delaminating.


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## Torx

Roof pitch, I'm lost.

Based on the adjacent garage I've used 2.5°. Internet calculators (I'm not clever) say this is 0.52:12 or 1:23? 







Roof covering...probably torch on felt.


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## Molynoox

Torx, looking really good! Exciting stuff isn't it.
4x2 isn't overkill, it's quite a big building, and 4x2 on 400 centres is fairly standard... It's certainly the most common config for garden room structures.
Sips are stronger than you think, also they get more expensive the more customised they need to be, windows etc
If you can buy the standard size panels and stitch them together yourself without the need for a design service and a custom cutting service then cost is probably similar to traditional framing.

On roof pitch, the standard is 1 in 40, or it might be easier to think of it as 25mm drop for every metre of building depth.
Example, if you have a 3 metre deep building it will be 75mm taller at the front than the back. 4m deep building would be 100mm. 3.5m would be somewhere in between, 87.5mm. not sure if that helps  

Martin


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## Molynoox

Jameshow said:


> Agreed metal sheet would be best esp if insulated.
> 
> Otherwise I was thinking a cut roof on top of sips dosent make sense.
> 
> I think they would be fine for a roof.
> 
> I'd be more concerned with a floor as the foam could possibly compress under weight of a operator and machine tool??


From a functionality perspective the metal roofing sheets are hard to beat, very strong, insulative, quick to put up and waterproof your building in a day etc. But I just don't like the look of them  I don't know if that's a very valid perspective but it's where I am. Not that EPDM looks amazing, but I prefer it.
Martin


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## Torx

Molynoox said:


> Torx, looking really good! Exciting stuff isn't it.
> 4x2 isn't overkill, it's quite a big building, and 4x2 on 400 centres is fairly standard... It's certainly the most common config for garden room structures.
> Sips are stronger than you think, also they get more expensive the more customised they need to be, windows etc
> If you can buy the standard size panels and stitch them together yourself without the need for a design service and a custom cutting service then cost is probably similar to traditional framing.
> 
> On roof pitch, the standard is 1 in 40, or it might be easier to think of it as 25mm drop for every metre of building depth.
> Example, if you have a 3 metre deep building it will be 75mm taller at the front than the back. 4m deep building would be 100mm. 3.5m would be somewhere in between, 87.5mm. not sure if that helps
> 
> Martin



Thanks, that does help! Although different roofing materials (even different manufacturers it seems) call for quite different figures. 

Still thinking about the roof construction / materials but it’ll likely end up being pretty basic as I just need to have somewhere watertight for winter storage at the moment, I’ve probably already blown the budget insulating the floor, but I can do the rest at a later date.


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## Spectric

Molynoox said:


> From a functionality perspective the metal roofing sheets are hard to beat


But make sure you have good insulation underneath otherwise the warm air in the workshop will condense on the cold metal and you will have rain.

As for the slope, think of that as a storage area underneath so 25 to 30° and look at 41/1000 Tile Form 0.6 Thick Mica Coated Roof Sheet

or look at these Eternit Fibre Cement Sheets | Roofing Superstore® which are another option.

I wanted my shed to blend in and not look industrial so as I have an apex roof and sarking boards I had it tiled with slates.


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## Molynoox

Spectric said:


> But make sure you have good insulation underneath otherwise the warm air in the workshop will condense on the cold metal and you will have rain.
> 
> As for the slope, think of that as a storage area underneath so 25 to 30° and look at 41/1000 Tile Form 0.6 Thick Mica Coated Roof Sheet
> 
> or look at these Eternit Fibre Cement Sheets | Roofing Superstore® which are another option.
> 
> I wanted my shed to blend in and not look industrial so as I have an apex roof and sarking boards I had it tiled with slates.


Sorry, I was talking about the insulated Kingspan type metal/ PIR roof panels, not the metal sheets which, as you say, are a condensates dream


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## isaac3d

Torx said:


> Stud layout...2 x 4s again - overkill? Probably.
> 
> View attachment 141140


Probably not overkill. Better to be safe than sorry anyway, especially if you hang heavy duty shelving for storing a lot of timber.


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## Torx

isaac3d said:


> Probably not overkill. Better to be safe than sorry anyway, especially if you hang heavy duty shelving for storing a lot of timber.


Are 2 x 4 ok for the roof too?


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## Molynoox

Torx said:


> Are 2 x 4 ok for the roof too?


If your span is 2.5m you will need 5x2 but I think you will be ok at 600 centres rather than 400
You can check the span tables online
Martin


----------



## Spectric

Molynoox said:


> If your span is 2.5m you will need 5x2 but I think you will be ok at 600 centres rather than 400
> You can check the span tables online


But that will depend on the roof covering, there is a lot of weight difference between slate, concrete tiles and profiled metal sheeting.


----------



## Molynoox

Spectric said:


> But that will depend on the roof covering, there is a lot of weight difference between slate, concrete tiles and profiled metal sheeting.


True


----------



## Torx

Molynoox said:


> If your span is 2.5m you will need 5x2 but I think you will be ok at 600 centres rather than 400
> You can check the span tables online
> Martin


Ah, good point. Although I found myself pondering the storage available for an apex roof last night so things might change again yet…


----------



## Torx

I'm leaning towards an apex roof now. What do you vote for? 







It feels a bit narrow but I do like the idea of somewhere to chuck long pieces of material. No idea how to build an apex roof though, so more research needed when I'd rather be actually doing stuff. Although if I leave it long enough maybe I'll be able to step outdoors without my eyeballs sweating.


----------



## Molynoox

Is there a height difference?
Seems to be, and if that is the case why not build the flat roof version at the pent roof height and get even more storage space....

I like the look of the apex version though, a bit different from the norm.

Martin


----------



## Torx

Molynoox said:


> Is there a height difference?
> Seems to be, and if that is the case why not build the flat roof version at the pent roof height and get even more storage space....
> 
> I like the look of the apex version though, a bit different from the norm.
> 
> Martin


From what I can gather you get 2.5m to the eaves with either design, but the max height can be up to 4m, the apex is 3.3m


----------



## Molynoox

Are you within 2m of the boundary? If so then you are limited to 2.5m height with either design.


----------



## Torx

Molynoox said:


> Are you within 2m of the boundary? If so then you are limited to 2.5m height with either design.



Rats, you’re right, I don’t know how I missed that. Ah well, pent it is, and lower again as I’d had the eaves at 2.5m. Or planning I suppose, another setback.


----------



## Molynoox

At least we spotted it now rather than later


----------



## Jameshow

How about shallow trussed roof with space for storage? 

Build some trusses 4" deep at each end 20" deep in the middle. 

Gives you the shallow apex and storage on top of a 2m high wall.

To be really clever put a hatch in the eves for easy access.....


----------



## Torx

Right, didn't want an apex roof anyway, didn't lose much height.

Any comments on stud layout before I go on? Family for scale:







Centre lines represent 8' x 4' sheets, hence the slightly odd stud spacing with some needed to overlap the sheets.

No idea what I'm doing, if you haven't noticed yet.

Also, I acquired another window.


----------



## Jameshow

Do you really need 3 studs either side of the doors / windows? 

1/2 would be fine?


----------



## Torx

Jameshow said:


> Do you really need 3 studs either side of the doors / windows?
> 
> 1/2 would be fine?


I wondered that too, thanks, I'll lose one.


----------



## Fitzroy

Why is your wife wearing a bikini in your shed and you need to install a toilet as your daughter is bursting! I like the wide high window design.

My shed is a similar design and on the rear and side walls where I had no windows I used 600mm spacing, plenty strong enough. On the front and side with windows it made little odds to the number of timbers as the design to incorporate the windows and door drove the stud arrangement.

My roof span is 3.2m and I used 6x2s in the roof, this is also to enable a cold roof design, with 100mm insulation and a vented 50mm air gap above. 

Personally I'd steer clear of torch on felt. I've had plenty of sheds over the years with felt and it is not as durable as the EPDM on my current shed. Installing a single sheet with no joints is such an easy and quick way to get the building watertight. If you had upstands and internal corners it's a different beast but a big flat pent roof is crying out for it.

F.


----------



## Torx

Fitzroy said:


> Why is your wife wearing a bikini in your shed and you need to install a toilet as your daughter is bursting! I like the wide high window design.
> 
> My shed is a similar design and on the rear and side walls where I had no windows I used 600mm spacing, plenty strong enough. On the front and side with windows it made little odds to the number of timbers as the design to incorporate the windows and door drove the stud arrangement.
> 
> My roof span is 3.2m and I used 6x2s in the roof, this is also to enable a cold roof design, with 100mm insulation and a vented 50mm air gap above.
> 
> Personally I'd steer clear of torch on felt. I've had plenty of sheds over the years with felt and it is not as durable as the EPDM on my current shed. Installing a single sheet with no joints is such an easy and quick way to get the building watertight. If you had upstands and internal corners it's a different beast but a big flat pent roof is crying out for it.
> 
> F.



It does seem to make a lot of sense, but why don’t commercial roofers seem to like it? Perhaps they like coming back to re-do felt roofs every 5 years?


----------



## Jameshow

Same reason hair dressers only take a little off!!


----------



## Torx

Without the additional studs around the doors / windows, the biggest spacing between centres is 554mm, worth having another here, or are the double studs either side adequate anyway?


----------



## Torx

Fitzroy said:


> Why is your wife wearing a bikini in your shed



It is a bit of a distraction at times, if I'm honest. I've been thinking about having a word.


----------



## Molynoox

looks good  
a small comment on stud spacings - you have optimised for imperial sheets, this means if you plasterboard the inside (which is metric) all your sheets will fall slightly short of the stud and you will get a lot of waste. PB is very cheap so not a huge issue, but the cuts do take time.
only real way to avoid that is using metric sheathing but that is quite rare (restricted to I think 11mm OSB only)
you may not be doing plasterboard on inside, in which case you can just ignore.

Martin


----------



## Torx

Molynoox said:


> looks good
> a small comment on stud spacings - you have optimised for imperial sheets, this means if you plasterboard the inside (which is metric) all your sheets will fall slightly short of the stud and you will get a lot of waste. PB is very cheap so not a huge issue, but the cuts do take time.
> only real way to avoid that is using metric sheathing but that is quite rare (restricted to I think 11mm OSB only)
> you may not be doing plasterboard on inside, in which case you can just ignore.
> 
> Martin



Good point, definitely something to bear in mind for the next one which will be more of an office space, but this one is just a shed / workshop extension so I'm thankful I don't have to worry about that!


----------



## Torx

Side question:

Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?


----------



## Jameshow

Torx said:


> Side question:
> 
> Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?


Most people aren't conversant with metal roofing. I think it's better in every way. 

Obviously it need to be corrugated. 

All you need is a small angle grinder and the right screws.


----------



## Jones

Low pitch roofs will often have standing water caused by debris dams or movement in the underlying structure such as timber shrinkage, bowing or just temperature movements. Even though the fixings for metal roofing have gaskets this can cause leaks, also corrosion of metals and coatings will occur if puddles form. So metal roofing must have enough fall so there's no risk of puddling or debris build up causing permanently damp areas . EPDM can be used as a swimming pool liner, sometimes inadvertantly when internal downpipes get blocked.


----------



## Fitzroy

Torx said:


> Side question:
> 
> Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?


My outhouse had a shallow roof that had corrugated iron on it, the wind would blow the water back up the roof and it would leak at the head end, where it was tucked under the tiles. A terrible design which the EPDM replacement didn't solve in being EPDM, but it did allow me to create an upstand under the slates with the EPDM formed over the top.


----------



## Torx

Jones said:


> Low pitch roofs will often have standing water caused by debris dams or movement in the underlying structure such as timber shrinkage, bowing or just temperature movements. Even though the fixings for metal roofing have gaskets this can cause leaks, also corrosion of metals and coatings will occur if puddles form. So metal roofing must have enough fall so there's no risk of puddling or debris build up causing permanently damp areas . EPDM can be used as a swimming pool liner, sometimes inadvertantly when internal downpipes get blocked.


Ah, that makes sense, I didn’t consider the fixings. I do like the idea of metal roofing but I think condensation might also be a problem (if it’s not done right).


----------



## Molynoox

I have nothing against the metal roof sheets, but condensation would be my biggest concern with them also.

Because of the shape of the sheets (i.e. not flat), you can't easily push the insulation tight up against it to close off the air gap next to the cold metal (which is where the condensate will form). Especially if using non compressible insulation like PIR because it wont fit to the curves of the sheet.
If you want metal, the kinspan panels are a nice way around that as the PIR is moulded 'inside' the sheets in the factory, thus reducing the problematic air gap to zero.

My current thoughts / preference on roofing options for flat roof sheds, in order of preference:

1. *sedum over EPDM* (expensive and needs stronger roof=thicker joists/or metalwork=less head height/or even more cost if sticking to 2.5m)
2. *artificial grass over EPDM* (100% waterproof, looks nicer than EPDM arguably, not sure on the grass maintenance?)
3. *EPDM* (looks 'OK', lasts for 30 years, 100% waterproof and maintenance free, quickly makes building waterproof)
4. *kingspan panels* (look a bit industrial, strong /can do big spans, easy and fast to assemble, 100% waterproof and maintenance free)
5. *felt* (doesn't last well, doesn't look good, but gets the job done and is cheap, in short term anyway)
6. *metal sheeting* (industrial look, potential condensate problem, not always waterproof, not always maintenance free)

GRP should be in there but I don't know enough about it other than it looks complex, messy, weather dependant, specialist etc

All in my opinion only 

Martin


----------



## Torx

Molynoox said:


> I have nothing against the metal roof sheets, but condensation would be my biggest concern with them also.
> 
> Because of the shape of the sheets (i.e. not flat), you can't easily push the insulation tight up against it to close off the air gap next to the cold metal (which is where the condensate will form). Especially if using non compressible insulation like PIR because it wont fit to the curves of the sheet.
> If you want metal, the kinspan panels are a nice way around that as the PIR is moulded 'inside' the sheets in the factory, thus reducing the problematic air gap to zero.
> 
> My current thoughts / preference on roofing options for flat roof sheds, in order of preference:
> 
> 1. *sedum over EPDM* (expensive and needs stronger roof=thicker joists/or metalwork=less head height/or even more cost if sticking to 2.5m)
> 2. *artificial grass over EPDM* (100% waterproof, looks nicer than EPDM arguably, not sure on the grass maintenance?)
> 3. *EPDM* (looks 'OK', lasts for 30 years, 100% waterproof and maintenance free, quickly makes building waterproof)
> 4. *kingspan panels* (look a bit industrial, strong /can do big spans, easy and fast to assemble, 100% waterproof and maintenance free)
> 5. *felt* (doesn't last well, doesn't look good, but gets the job done and is cheap, in short term anyway)
> 6. *metal sheeting* (industrial look, potential condensate problem, not always waterproof, not always maintenance free)
> 
> GRP should be in there but I don't know enough about it other than it looks complex, messy, weather dependant, specialist etc
> 
> All in my opinion only
> 
> Martin


I like the idea of a sedum roof, maybe next time. Most of the metal roofing materials (including the kingspan, I think) do require a much greater pitch, so out of the question for this. 

How does the rubber hold up in extreme temperatures like we’ve experienced recently?


----------



## Torx

@Fitzroy did you fit these things (gutter trim) on the EPDM roof? 






Just wondering what I should allow for them in the height, looks like about 20mm?


----------



## Torx

Torx said:


> @Fitzroy did you fit these things (gutter trim) on the EPDM roof?
> 
> View attachment 141892
> 
> 
> Just wondering what I should allow for them in the height, looks like about 20mm?


Ah ha






Found a good site for this stuff - Rubber Roofing Systems, EPDM Rubber Roofs & Materials | Rubber4Roofs


----------



## Torx

Doors.

I've been considering buying one of these... 









External Solid Pine Unfinished Framed, Ledged & Braced Door (RFLB)


One of our most popular brands over the years, LPD Doors boasts a 35 year experience that is evident in their designs that continue to raise the benchmark of manufacturers everywhere. Including a wide selection of designs and popular materials, the LPD Doors External Essentials collection boasts...




www.leaderdoors.co.uk





....as they're cheap and relatively solid (I've had one on my garage for 3 years and only treated once, and it's been fine so far...) then clad over it with whatever I decide on. 

The door height at the moment is 1900ish.

This is mainly out of laziness, just to get a door on it quickly.

Any comments?


----------



## Jameshow

Torx said:


> Doors.
> 
> I've been considering buying one of these...
> 
> 
> 
> 
> 
> 
> 
> 
> 
> External Solid Pine Unfinished Framed, Ledged & Braced Door (RFLB)
> 
> 
> One of our most popular brands over the years, LPD Doors boasts a 35 year experience that is evident in their designs that continue to raise the benchmark of manufacturers everywhere. Including a wide selection of designs and popular materials, the LPD Doors External Essentials collection boasts...
> 
> 
> 
> 
> www.leaderdoors.co.uk
> 
> 
> 
> 
> 
> ....as they're cheap and relatively solid (I've had one on my garage for 3 years and only treated once, and it's been fine so far...) then clad over it with whatever I decide on.
> 
> The door height at the moment is 1900ish.
> 
> This is mainly out of laziness, just to get a door on it quickly.
> 
> Any comments?


Why not use 18mm plywood with 3x2 lapped framework. 

Put it ply on outside temporarily and then reverse and clad on the outside.


----------



## Fitzroy

Torx said:


> @Fitzroy did you fit these things (gutter trim) on the EPDM roof?
> 
> View attachment 141892
> 
> 
> Just wondering what I should allow for them in the height, looks like about 20mm?



Nope I did not, I just brought the epdm around the side of the roof and pinned underneath with a small Barton to act as a drip edge. The trims were expensive I thought and served little purpose as there is no guttering on my shed so no issue where the run off happens.


----------



## Dabop

Torx said:


> Side question:
> 
> Can anyone explain (in laymans terms), why felt / rubber etc., are suitable for low pitch roofing but (seemingly impermeable) sheet steel is not? I can't quite get my head around this, I must be missing something obvious - wind?


I think it is local usage- here in Australia metal roofs are the standard for sheds (and since the 1970's houses as well)
Especially colourbond (powdercoated) sheeting- my entire shed is made of it- 35 year guarantee- on the powdercoat not coming off or discolouring... the roof itself will outlast me by a considerable margin...
Leaks are practically unheard off (usually only after a cyclone or something damages the roof beforehand)- I have seen US manufacturers saying they put the screws in the valley- so relying on the rubber washers to do sealing- where ours here are the exact opposite- that voids the warranty for leakage- as they say to put them on the 'tops' of the ridges- so unless your rain is of 'Noah's loading the ark' levels, then the possibility of leakage is next to none- the entire 'gully' has to be filled up to the level of the ridges- even on a flat roof thats unlikely... (and the rubber seal on the screw has to have deteriorated as well)
As for wind, my shed is cyclonic rated, and i know from experience they hold up extremely well to cyclones, A shed from the same company survived with no damage at all, unlike the house (old fibro farm house) that needed quite a few sheets on the walls replacing (its metal roof was fine however)
Metal roofing is by far the best option imho


----------



## Molynoox

Dabop said:


> I think it is local usage- here in Australia metal roofs are the standard for sheds (and since the 1970's houses as well)
> Especially colourbond (powdercoated) sheeting- my entire shed is made of it- 35 year guarantee- on the powdercoat not coming off or discolouring... the roof itself will outlast me by a considerable margin...
> Leaks are practically unheard off (usually only after a cyclone or something damages the roof beforehand)- I have seen US manufacturers saying they put the screws in the valley- so relying on the rubber washers to do sealing- where ours here are the exact opposite- that voids the warranty for leakage- as they say to put them on the 'tops' of the ridges- so unless your rain is of 'Noah's loading the ark' levels, then the possibility of leakage is next to none- the entire 'gully' has to be filled up to the level of the ridges- even on a flat roof thats unlikely... (and the rubber seal on the screw has to have deteriorated as well)
> As for wind, my shed is cyclonic rated, and i know from experience they hold up extremely well to cyclones, A shed from the same company survived with no dagae at all, unlike the house (old fibro farm house) that needed quite a few sheets on the walls replacing (its metal roof was fine however)
> Metal roofing is by far the best option imho
> View attachment 141920


That's interesting. Makes total sense fixing it on the peaks.
What about the condensate issue, is that not a problem in Australia?

Martin


----------



## Dabop

Molynoox said:


> That's interesting. Makes total sense fixing it on the peaks.
> What about the condensate issue, is that not a problem in Australia?
> 
> Martin


We don't worry about it for most sheds, but houses use a combination fiber insulation/silver sarking sheet under the roof itself- mine I had it installed as this will be a working shed, and we get 40C plus temps in summer- so insulation stops the worst of that 



That's the 'backside' of the triangular wall in the first pic, taken inside the main shed, the first was a 'leanto' that will eventually be my machining workshop proper


----------



## Torx

Fixing roof to walls - these things?


----------



## clogs

I've built steel sheds n workshops all over the world.....
Here in Crete the go to sheeting is double skinned steel with 40mm of high density foam....
It is self supporting at 3m between joist and thats exactly what I use for my caravan and new shed build....plus on my caravan roof there is a solar water system and I reg walk over said roof it to inspect it....on the new shed (160m2) I will use an extra purlin, thats for the photo elec cells, (were going off grid) reason for the extra support is the high winds we get in winter not the weight.....
no condensation or leaks......
had a steel scaffold pole hit the roof in a maj storm it ripped the outer skin but still no leaks..........
Cant understand why people use felt or wood.....as steel is the same price or better.....
fast, easy contsruction methods for a shed /mini barn is a steel frame, with walls n roof with the above steel sheeting...u can specify quite a few colours now......plenty of used roofing in the UK...Oh, u lucky people....
done correctly all the framing is bolted together, welding and cutting is on the floor.....
pour the pad set the studs and with 2 guys it can be water tight in a weekend....
PLUS u can take it down if u need too (moving) or to add on an extra room....
Also u dont need heavy girders providing u frame properly......
I use 150x50x 3mm thick hollow box.....any small welding firm will cut and weld the gussets.....galv is nice but paint will suffice.....
this is 7.5mx7mx 4mH...and no the front legs are not drunk....hahaha....
a mate and myself assembled this in a weekend...just a temp cover for the crates....quite a bit more steel will be used in the final shed....
spent a week making the frame (welding and drilling).....it's now double this size....
caravan cover is 11mx7.5mx3.5m.....notice a steel box frame for the terrace....cheap...
those roofing sheets are just a 1m covering (wide) and 2 of us can man handle a 7.5m length.....they make a special shaped washer for the fixing screws.....
(NOTE, fixings on the ridges of the sheet not the valleys.....)
I did use my forklift to get em up there tho....
but a little shed, they can be carried easily and even down the side of the house....along with the frame.....simples.......
the roof pitch is 5 deg on mine as we never get snow....at least 10deg min but 15 is ideal for UK......
when finished they will get hand made HD guttering for the monsoon rains in winter....
I did make the storage shed to use an extra 3 legs but to get the crates in it was easyer to leave them off.....that has stood for 3 years now....
note, the 1 ton bags of stone to hold it down.....hahaha...
good luck...
ps, the wood for the decking, 7mx4m was almost €800 three years ago....
here gazebo's etc are now made from steel.....wood is just mental money.....
5mLx150x 50mm joist, rough sawn [email protected] was over €40 each 2 years ago....now.....??????


----------



## Torx

clogs said:


> I've built steel sheds n workshops all over the world.....
> Here in Crete the go to sheeting is double skinned steel with 40mm of high density foam....
> It is self supporting at 3m between joist and thats exactly what I use for my caravan and new shed build....plus on my caravan roof there is a solar water system and I reg walk over said roof it to inspect it....on the new shed (160m2) I will use an extra purlin, thats for the photo elec cells, (were going off grid) reason for the extra support is the high winds we get in winter not the weight.....
> no condensation or leaks......
> had a steel scaffold pole hit the roof in a maj storm it ripped the outer skin but still no leaks..........
> Cant understand why people use felt or wood.....as steel is the same price or better.....
> fast, easy contsruction methods for a shed /mini barn is a steel frame, with walls n roof with the above steel sheeting...u can specify quite a few colours now......plenty of used roofing in the UK...Oh, u lucky people....
> done correctly all the framing is bolted together, welding and cutting is on the floor.....
> pour the pad set the studs and with 2 guys it can be water tight in a weekend....
> PLUS u can take it down if u need too (moving) or to add on an extra room....
> Also u dont need heavy girders providing u frame properly......
> I use 150x50x 3mm thick hollow box.....any small welding firm will cut and weld the gussets.....galv is nice but paint will suffice.....
> this is 7.5mx7mx 4mH...and no the front legs are not drunk....hahaha....
> a mate and myself assembled this in a weekend...just a temp cover for the crates....quite a bit more steel will be used in the final shed....
> spent a week making the frame (welding and drilling).....it's now double this size....
> caravan cover is 11mx7.5mx3.5m.....notice a steel box frame for the terrace....cheap...
> those roofing sheets are just a 1m covering (wide) and 2 of us can man handle a 7.5m length.....they make a special shaped washer for the fixing screws.....
> (NOTE, fixings on the ridges of the sheet not the valleys.....)
> I did use my forklift to get em up there tho....
> but a little shed, they can be carried easily and even down the side of the house....along with the frame.....simples.......
> the roof pitch is 5 deg on mine as we never get snow....at least 10deg min but 15 is ideal for UK......
> when finished they will get hand made HD guttering for the monsoon rains in winter....
> I did make the storage shed to use an extra 3 legs but to get the crates in it was easyer to leave them off.....that has stood for 3 years now....
> note, the 1 ton bags of stone to hold it down.....hahaha...
> good luck...
> ps, the wood for the decking, 7mx4m was almost €800 three years ago....
> here gazebo's etc are now made from steel.....wood is just mental money.....
> 5mLx150x 50mm joist, rough sawn [email protected] was over €40 each 2 years ago....now.....??????
> View attachment 141938
> 
> View attachment 141939



I like everything about the stuff, but I just can't get the manufacturer's recommended pitch, without losing significant head room.


----------



## Torx

Roof design for comments please 

I can do this with 6 x sheets shown in blue. Not sure if the perimeter beam is necessary or even adds weight I could do without? Otherwise I'd probably just use a thicker UPVC facia or maybe do something with the cladding.

No noggins needed as it's under 2.4m span. 5" x 2" beams as suggested.




Thanks for all the advice so far, I feel like I'm almost ready to start doing something again without the anxiety of doing something wrong I'd have to undo...


----------



## Jameshow

Torx said:


> I like everything about the stuff, but I just can't get the manufacturer's recommended pitch, without losing significant head room.


Thier recommended pitch will be for industrial building your shed will be fine. 

A 4" over 8' gradient will be fine.


----------



## Torx

Jameshow said:


> Thier recommended pitch will be for industrial building your shed will be fine.
> 
> A 4" over 8' gradient will be fine.


I think it’s more like 3”, I’m tempted but I’d rather be 100% sure… I’ve mostly settled on EPDM now, I’m just curious.


----------



## Torx

What’s the consensus on whether treated timber is needed for the walls & roof?


----------



## Inspector

Torx said:


> What’s the consensus on whether treated timber is needed for the walls & roof?


Treated wood is normally for wet, ground contact or termite problems. If you are making it to be dry why would you want treated wood? Houses I helped build out of high school in the mid seventies are still standing with no issues. I could see using a treated sill but not beyond that. If you feel there is a need for treated framing then the sheathing should also be treated stock.

Pete


----------



## Torx

There doesn’t seem to be a lot of difference in cost (online anyway, haven’t asked over the counter yet and sometimes the prices change). Approx £1 per length difference, so £50/60 more to use treated timber throughout.


----------



## Molynoox

I wouldn't want to contradict Pete, but I think there may be some value in using treated wood. The reason I feel that way is because sheds and garden rooms are not built like houses, not subject to building control etc. So they are often not vented and sometimes not sealed properly. You do tend to hear of more issues with condensation and moisture for garden buildings than with houses. That's all a bit anecdotal and might not be true but I would say there is a case to be made for treated especially as the additional cost is so minimal. I'm not advocating over engineering but for me when I did the cost / risk balance it swung in favour of using treated. But it's a good point about the OSB not being treated and hence perhaps the weakest link.... Although I think OSB3, which most people use, does have a level of resilience designed into it that makes it suitable for outdoor environments?

Martin


----------



## Inspector

Our 2x4x8' studs are $6Cad. The treated ones (not ground contact rated) are $9Cad. That makes building with treated 50% more and that doesn't factor in the corrosion resistant fasteners you have to use for treated lumber. 
I won't loose any sleep if you contradict me. It's okay. 

Pete


----------



## Terry - Somerset

There are a variety off different building practices around Europe - I'm not sure whether this is a simple consequence of historical familiarity, or something more fundamental leading to development along different tracks. The main variables may be:

climate - the Med is typically very different to the UK - warmer, more sunshine, less rain. Other bits of Europe may have more snow, greater seasonal temperature variation. Compare Alpine to "Costa" type design and structures.
local material availability - may be a historical legacy despite improved transport capability. UK had very distinct regional differences - eg: roof using thatch, slate, tile, etc.
longevity - UK aspires to a long design life of 100+ years with limited major repairs.. In other parts of the world no more than a couple of decades seems acceptable. Some Gulf states commonly replace buildings less that 15 years old as the existing no longer meet the need. 
So debate over the merits of steel roofs compared to felt and bitumen or EDPM (modern alternative) may be underpinned by characteristics other than cost, resistance to leaks, wind loading etc.


----------



## Jones

Treated timber will be treated against fungal decay and insects. It would be difficult and expensive to replace at a later date so you should use treated. For non structural parts which can be easily replaced or may be modified untreated is ok.


----------



## Torx

Jameshow said:


> Thier recommended pitch will be for industrial building your shed will be fine.
> 
> A 4" over 8' gradient will be fine.



You’re dead right about this (not that I had any doubt), I went camping in Wales for a few days and it’s used all over at very low pitches


----------



## Torx

Framed the front wall today, 6yr old was helping 






I can just about raise this on my own


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## Torx

Found some random no brand (Chinese origin) membrane I bought for something else years ago and forgot about, is there any reason not to use this? It seems to do the job, left the tap on it for a few minutes and the water didn’t get through.


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## Jameshow

Torx said:


> Found some random no brand (Chinese origin) membrane I bought for something else years ago and forgot about, is there any reason not to use this? It seems to do the job, left the tap on it for a few minutes and the water didn’t get through.
> 
> View attachment 142608


Why not looks fine...


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## Torx

Managed to get the walls up, then it started raining. It’s stopped now so might start the roof later


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## Jameshow

If leaving any time the put a ridge pole up to drain off water. 

A bit of 4x2 in the workmate in the middle would do too.


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## Torx

Jameshow said:


> If leaving any time the put a ridge pole up to drain off water.
> 
> A bit of 4x2 in the workmate in the middle would do too.



Good call, I’ll do that. Although that tarp is full of holes, eBay seller refunded it though so can’t complain and don’t feel bad about stapling it. Have a better one I can put over once the boards are on the roof.


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## Torx

Hardly necessary to use it but I’m really liking this thing Father Christmas brought for me


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## Torx

Thinking about going for a darker colour, might be able to get away with cheaper cladding if it doesn’t have to be pretty.






Wife isn’t sure


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## Molynoox

Torx said:


> Thinking about going for a darker colour, might be able to get away with cheaper cladding if it doesn’t have to be pretty.
> 
> View attachment 142978
> 
> 
> Wife isn’t sure


BLACK! 

I think it's a good tactic to paint a cheaper wood. Doesn't have to be black though, there are some really nice colours available. The bluey grey ones are really popular at moment and they look great.


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## Torx

Managed to get the roof on today, despite the twisted timber - lots of interesting clamping strategies…


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## Jameshow

Any fall to that roof?


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## Torx

Jameshow said:


> Any fall to that roof?



Yes, I can’t remember what it is exactly, it’s very little but the photos make it look non existent. About 100mm over 3m


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## Torx

Just priced up UPVC facias - £400! Think I could get it down a little bit elsewhere but I wasn’t anticipating paying anything like that. I would simply fold over the rubber like @Fitzroy did, looks great, but I’ve always planned on having a gutter on this (I plan to chuck sheet materials behind it as much as anything). So I might get a hop on to sort out the cladding so I can use this for the facias, or maybe figure out a way to put a kerb around the edge with the EPDM, I’m not sure how the manufactured kerbs would look if I did it fitz style.


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## Jameshow

Torx said:


> Just priced up UPVC facias - £400! Think I could get it down a little bit elsewhere but I wasn’t anticipating paying anything like that. I would simply fold over the rubber like @Fitzroy did, looks great, but I’ve always planned on having a gutter on this (I plan to chuck sheet materials behind it as much as anything). So I might get a hop on to sort out the cladding so I can use this for the facias, or maybe figure out a way to put a kerb around the edge with the EPDM, I’m not sure how the manufactured kerbs would look if I did it fitz style.


Price of oil....


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## Torx

I could wrap the existing facia edge in lead for less money. Might look nice? Looks like approx £150? How to join it...more learning. It's an idea anyway.


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## Torx

Managed to get the roof and wall panels on over the weekend (only had about a day after other commitments)

I’m wondering about cladding just 3 sides, do people just leave the Tyvek or can anyone recommend a (cheap) non-combustible cladding?


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## johna.clements

Tyvek would get ripped eventually. 
UV will also damage it.


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## flying haggis

Spectric said:


> With this design, once you have the base in place use wire mesh of some sort to seal all the edges to prevent rodents living underneath, mesh size will determine who can get in!


i used this mesh to stop critters getting under my shed, nailed the bearers all the way round the base








Sabrefix Brick Reinforcing Coil Galvanised DX275 20m x 112mm


Order online at Screwfix.com. Galvanised steel. FREE next day delivery available, free collection in 5 minutes.



www.screwfix.com


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## Torx

johna.clements said:


> Tyvek would get ripped eventually.
> UV will also damage it.


I think I’ll have to find something like Hardieboard or Cedral, but it’s not easy (cheap) to get hold of in small quantities and I don’t really want to use it for the whole shed. Found some larch cladding nearby, but it’s finding time to go and have a look, I’m away overnight with work almost every day for 3 weeks now. Can’t decide if I should go vertical or horizontal with the cladding but I don’t really want any joints and I can’t find lengths over 3.6m so that’s probably the answer. The waste from doing it vertically will do the eaves and windows. Need to get the roof on before it gets too cold - 4deg for the rubber. Might just buy it and leave it overhanging until I figure out a facia. Only have a temporary door/hatch. 

Just reached the realisation that the easy bit is over. 

The good news is it’s dried out nicely and only 1/7 neighbours have commented (nothing negative).


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## Torx

Got a discount code for the rubber roof from Ali Dymock from YouTube who has a great series on building a garden room 



Result! Will get it ordered tomorrow.


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## Torx

Tyvek (type stuff) went on today, after routing out the window, which was going well until the bit lost its bearing

Added a small radius on all the sharp edges while I had the router out to avoid any tears.

Great fun putting that on in the wind and rain!


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## johna.clements

You must have a big cat to use that cat flap.


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## Torx

Put on battens to hold down Tyvek until cladding arrives or leave battens off to avoid possible water - opinions? We had a bit of wind yesterday and I had to rush out and put more staples in but it seems to have held up. Cladding may or may not be fitted until next year


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## Jameshow

I'd put on battens tbh. 

And cladding asap too..


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## Molynoox

Torx said:


> Put on battens to hold down Tyvek until cladding arrives or leave battens off to avoid possible water - opinions? We had a bit of wind yesterday and I had to rush out and put more staples in but it seems to have held up. Cladding may or may not be fitted until next year


no reason not to add the battens I don't think.
Ensure they are vertical, not horizontal, so that water cannot pool, and if they need to be horizontal because your cladding is vertical then you need to double batten:
vert batten -> horiz batten -> vert cladding
Check Tyvek website for UV resilience, it should be waterproof but its not designed to be in the sun so might have a UV volatility

Martin


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## Fitzroy

Battens for deffo, once a corner lifts in the wind it'll be in tatters before you even notice.


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## Fitzroy

Molynoox said:


> no reason not to add the battens I don't think.
> Ensure they are vertical, not horizontal, so that water cannot pool, and if they need to be horizontal because your cladding is vertical then you need to double batten:
> vert batten -> horiz batten -> vert cladding
> Check Tyvek website for UV resilience, it should be waterproof but its not designed to be in the sun so might have a UV volatility
> 
> Martin


What this man said is the correct way if you are using vertical cladding. I was a cheap skate and did not do this, I simply angled the top of each batten on the planer so that any water did not pool against the membrane. This however meant I planed away the tanalising (sp?) chemical so all my battens will rot early and the cladding will fall off. So is the will of the shed building gods.


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## Fitzroy

Torx said:


> Tyvek (type stuff) went on today, after routing out the window, which was going well until the bit lost its bearing
> 
> Added a small radius on all the sharp edges while I had the router out to avoid any tears.
> 
> Great fun putting that on in the wind and rain!
> 
> View attachment 144141
> 
> 
> View attachment 144140
> 
> 
> View attachment 144139



I remember clearly routing out the windows as it was great fun, if a little scary to hold a 2.5kW router freehand like that. Thankfully a carbide router is much harder than a stainless steel screw.


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## Torx

Jameshow said:


> I'd put on battens tbh.
> 
> And cladding asap too..





Molynoox said:


> no reason not to add the battens I don't think.
> Ensure they are vertical, not horizontal, so that water cannot pool, and if they need to be horizontal because your cladding is vertical then you need to double batten:
> vert batten -> horiz batten -> vert cladding
> Check Tyvek website for UV resilience, it should be waterproof but its not designed to be in the sun so might have a UV volatility
> 
> Martin





Fitzroy said:


> What this man said is the correct way if you are using vertical cladding. I was a cheap skate and did not do this, I simply angled the top of each batten on the planer so that any water did not pool against the membrane. This however meant I planed away the tanalising (sp?) chemical so all my battens will rot early and the cladding will fall off. So is the will of the shed building gods.



Hadn’t thought of all that, I think the cladding will be vertical and I was just mulling over angling the battens but it all makes good sense. Thanks!


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## Molynoox

Torx said:


> Hadn’t thought of all that, I think the cladding will be vertical and I was just mulling over angling the battens but it all makes good sense. Thanks!


The step you are about to make is one which I almost screwed up, the door fitting. I didn't really think about the battens and cladding depth when positioning the doors and windows, I just defaulted into placing in the middle of the wall. My thinking was that I wanted the reveals to be same size on both sides. It is the sill that needs thinking about though... I got lucky and the sill protruded past the cladding, but only because I did horizontal cladding and hence had only one layer of battens.
I didn't fit them myself, just instructed the door fitters where to put them... when they asked me I hadn't really thought it through and almost randomly made that decision.
Think about your sill depth too, this is usually configurable, so have a think about what you want and need 

Martin


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## Molynoox

Fitzroy said:


> What this man said is the correct way if you are using vertical cladding. I was a cheap skate and did not do this, I simply angled the top of each batten on the planer so that any water did not pool against the membrane. This however meant I planed away the tanalising (sp?) chemical so all my battens will rot early and the cladding will fall off. So is the will of the shed building gods.


Haha, nice idea though!


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## Torx

Molynoox said:


> The step you are about to make is one which I almost screwed up, the door fitting. I didn't really think about the battens and cladding depth when positioning the doors and windows, I just defaulted into placing in the middle of the wall. My thinking was that I wanted the reveals to be same size on both sides. It is the sill that needs thinking about though... I got lucky and the sill protruded past the cladding, but only because I did horizontal cladding and hence had only one layer of battens.
> I didn't fit them myself, just instructed the door fitters where to put them... when they asked me I hadn't really thought it through and almost randomly made that decision.
> Think about your sill depth too, this is usually configurable, so have a think about what you want and need
> 
> Martin



Thanks, hadn’t thought about that, but then I haven’t actually got a door. The window was ordered by mistake at the wrong length by someone who intended it to be installed vertically, so I’ve only got a short sill and will have to think of something. I made a cock up with the framing for the window and made it 45mm too tall but I think I can take advantage of this for a sill. When I work it out. I’m completely making this up as I go along at the moment. I’m away from home at the moment but I think the roof has arrived so I’ll hopefully lay it out over the weekend as I think it needs to rest. Also found a good source for the facia etc. so hoping to get that ordered when I can sit down for a minute.






Black UPVC Fascia Board | UPVC Fascia Board | Brown Fascia Board | Plastics Hub


Shop black and brown UPVC Fascia Board at plasticshub.com. Fascia Capping Board is used in the exterior of the building, mainly residentially, and forms part of the roofline.




www.plasticshub.com


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## johna.clements

When I built my shed I was going to reuse the glass from the old shed that was being eaten by woodworm. But my mothers house was having new windows and they transposed the height and width when they made it. I have a bigger window that has two openings rather than a smaller single pane.


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## Torx

Got the plastics ordered last night, I’d have like to do the facia and soffit in wood but I still haven’t had time to go on a cladding hunting trip and since it will get a lot of abuse from the weather it seems like money well spent. 

Wife said she had a knock on the door today, from the neighbour directly behind. I was worried for a minute but apparently I’ve now been enlisted to help him build a shed as he’s impressed.


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## Torx

First productive weekend for a while, although I got very wet yesterday! Rubber roof glued down this afternoon (with the weather looking scarily gloomy). Impressed at how easy it is to put down, can’t see myself using anything else in future for similar projects. Soffits and facias nearly there, but the plastics company forgot to deliver the vented ones for the front so hopefully they’ll turn up this week. 

To do list

- finish facias, guttering
- find some timber for a windowsill
- install window
- make a door frame / door 
- sort out some cladding


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## Torx

Molynoox said:


> no reason not to add the battens I don't think.
> Ensure they are vertical, not horizontal, so that water cannot pool, and if they need to be horizontal because your cladding is vertical then you need to double batten:
> vert batten -> horiz batten -> vert cladding
> Check Tyvek website for UV resilience, it should be waterproof but its not designed to be in the sun so might have a UV volatility
> 
> Martin



I’m thinking about doing the back and sides in steel, corrugated or similar. Can’t make my mind up whether the batten orientation makes any difference, if I go straight to horizontal? (Or not, and put the sheeting the other way like this, but I’m not so sure…)


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## Fitzroy

Torx said:


> I’m thinking about doing the back and sides in steel, corrugated or similar. Can’t make my mind up whether the batten orientation makes any difference, if I go straight to horizontal? (Or not, and put the sheeting the other way like this, but I’m not so sure…)
> 
> View attachment 145570



That’s a pretty cool look, interesting solution for cladding. The battens give an attachment point for the cladding and create a air gap that can dry out is water penetrates the cladding which is just a ‘rain screen’.
With corrugated steel being impermeable you may argue that there will be no rain penetration so it’s irrelevant. If you wanted belt and braces I’d want this gap to breath so I would run the battens vertically and ensure a gap top and bottom with and insect mesh barrier.


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## Torx

Fitzroy said:


> That’s a pretty cool look, interesting solution for cladding. The battens give an attachment point for the cladding and create a air gap that can dry out is water penetrates the cladding which is just a ‘rain screen’.
> With corrugated steel being impermeable you may argue that there will be no rain penetration so it’s irrelevant. If you wanted belt and braces I’d want this gap to breath so I would run the battens vertically and ensure a gap top and bottom with and insect mesh barrier.


I could vent it into the soffit without too much trouble, then seal it along the top. It looks like insect mesh is available for profiled stuff but I’m not sure how effective it would be, tempted not to bother, I’m not sure how much of a pest insects could be (famous last words)


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## Fitzroy

Torx said:


> I could vent it into the soffit without too much trouble, then seal it along the top. It looks like insect mesh is available for profiled stuff but I’m not sure how effective it would be, tempted not to bother, I’m not sure how much of a pest insects could be (famous last words)


I have a few famous last word potentials with my shed. I think you understand the ideal and the trouble providing it, then you make a decision and history will be the judge.


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## rogxwhit

Torx said:


> I’m not sure how much of a pest insects could be


Wasp nests would block the ventilation ....


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## Torx

rogxwhit said:


> Wasp nests would block the ventilation ....


I’ve got an air compressor and a small boy who can run quite fast…


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## Torx

I think installing the corrugated cladding horizontally looks pretty good, the only reason I can find so far to avoid it is cleaning. It would save double battening.


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## Dave Moore

Torx said:


> I’ve got an air compressor and a small boy who can run quite fast…


Hi,
you can get perforated aluminium mesh which is set at 90degrees for air venting from cedral suppliers.
regards,
Dave


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## Torx

Bit of a break doing other things, plus the vented soffits still haven't turned up and I want to have a look at it fitted before I make a decision about cladding, but I'm pretty set on corrugated steel on the side and rear (probably galv or painted black to keep it 'non-combustible' as I found out from another member that the plastisol coated stuff will be combustible).

I think I mentioned that the UPVC window I got didn't come with a sill. Any comments on this arrangement?


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## Jameshow

You can buy upvc cill material. 

Or use a 4x2 with the corner planned off.


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## HOJ

Plastic windows usually have drainage slots in the bottom rebate, i'd be inclined to get a plastic cill so it can perform as it was intended to, must be a UPCV window supplier/maker locally that will have miles of the stuff


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## Torx

Jameshow said:


> You can buy upvc cill material.
> 
> Or use a 4x2 with the corner planned off.



That’s the plan - I could definitely get a sill but since I won’t have a matching UPVC door I think a wooden sill matching the cladding would look better and I’ll box in around the window. Just wondering if I’ve made any massive errors in the way I plan to fit the window, with the membrane etc, a lot of people wrap it inside the building but think cutting it halfway inside the frame makes better sense?


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## Molynoox

Torx said:


> Bit of a break doing other things, plus the vented soffits still haven't turned up and I want to have a look at it fitted before I make a decision about cladding, but I'm pretty set on corrugated steel on the side and rear (probably galv or painted black to keep it 'non-combustible' as I found out from another member that the plastisol coated stuff will be combustible).
> 
> I think I mentioned that the UPVC window I got didn't come with a sill. Any comments on this arrangement?
> 
> View attachment 146148​


Looks about right. I used that Dupont flexwrap stuff in addition to your layout but I don't think I needed to. It gives a more complete seal on the internal frame but I don't see water getting in there anyway.


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## HOJ

Torx said:


> I think a wooden sill matching the cladding would look better


Just seems like a lot of extra cost & effort to be honest, just be mindful, as I said, about the drainage holes in the windows.



Torx said:


> a lot of people wrap it inside the building but think cutting it halfway inside the frame makes better sense?


That's the way we do it, just fold it in and cut it off to the inside face.

Also why not use 9mm OSB rather than 11mm, its manufactured principally for this purpose, its nominally smaller though, to allow for expansion gaps.


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## Torx

HOJ said:


> Just seems like a lot of extra cost & effort to be honest, just be mindful, as I said, about the drainage holes in the windows.
> 
> 
> That's the way we do it, just fold it in and cut it off to the inside face.
> 
> Also why not use 9mm OSB rather than 11mm, its manufactured principally for this purpose, its nominally smaller though, to allow for expansion gaps.



I didn’t spot any drainage holes but I’ll have a closer look. I’ve already fitted the external skin in 11mm OSB but I’ll remember that for next time.


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## Joe1975

I have just built a 5m x 3m studio with a similar design. Just a few points.

EPDM was easy to install and looks great, there is no way I would suggest using anything else.
TYVEK house wrap is brilliant (although expensive), I injured my back during my build and had to delay things. The wrap has been stapled and battened on for about 18mths now and is still fully protecting the building waiting for me to finish the cladding.
I used 70mm PIR insulation in the walls with it tight up against the plasterboard. In retrospect it would probably have been cheaper and just as good to use 50mm centred in the cavity. The silver foil reflects heat only if there is an air cavity.
I used 9 Very solid (dug down 18” nearly to chalk bed, 5” reinforced concrete and three blocks) supports for the base and 5” timber, I think your method of more blocks but no foundations will prove to be better and much less work.
Don’t skimp on anything especially lighting and sockets. I think I spent five times longer researching, designing, planning and costing than building. Loved every minute. Enjoy the rest of the build.


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## Torx

Joe1975 said:


> I have just built a 5m x 3m studio with a similar design. Just a few points.
> 
> EPDM was easy to install and looks great, there is no way I would suggest using anything else.
> TYVEK house wrap is brilliant (although expensive), I injured my back during my build and had to delay things. The wrap has been stapled and battened on for about 18mths now and is still fully protecting the building waiting for me to finish the cladding.
> I used 70mm PIR insulation in the walls with it tight up against the plasterboard. In retrospect it would probably have been cheaper and just as good to use 50mm centred in the cavity. The silver foil reflects heat only if there is an air cavity.
> I used 9 Very solid (dug down 18” nearly to chalk bed, 5” reinforced concrete and three blocks) supports for the base and 5” timber, I think your method of more blocks but no foundations will prove to be better and much less work.
> Don’t skimp on anything especially lighting and sockets. I think I spent five times longer researching, designing, planning and costing than building. Loved every minute. Enjoy the rest of the build.



Pictures? 

Mines still in the Tyvek stuff too, but it seems ok at the moment. 






Cladding for back and sides (galv steel) has arrived but currently buried in the snow.

Actually I did put foundations under my blocks to about the same depth - probably unnecessary but I’m not sure this will always be a workshop - it was a lot of work, I think there’s about 2 tonnes of MOT altogether. 

I agree, the EPDM is great, wouldn’t consider anything else for another similar build.


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## Molynoox

Joe1975 said:


> I used 70mm PIR insulation in the walls with it tight up against the plasterboard. In retrospect it would probably have been cheaper and just as good to use 50mm centred in the cavity. The silver foil reflects heat only if there is an air cavity.


Careful doing that - generally speaking, centering PIR inside a cavity is not good, it would create an air pocket adjacent to the cold side. It does depend on your wall design though, if you don't have any external sheathing it's probably ok, if you do have external sheathing its probably not ok, especially if it's OSB 

By the way if you have any sources regarding the equivalency of the 50 Vs 70 I would be interested to take a read through it


----------

