# Shed / Workshop Build



## Haldane (31 Dec 2009)

Hello All

Now its almost finished I thought I'd post some pictures of my new shed / workshop (not sure what the difference is?) Any way started the build in middle of last Feb when had week off work ordered the materials for the base the previous week great weather and lots of sunshine, which changed completely as soon as I set foot outdoors on my weeks holiday







Area dug out and marked with pegs to try and level







Armoured power and alarm cable buried and run out from house in readiness (shed to have its own zone on the main alarm panel) also
start to move roadstone (about 6 tonne) from front of house by
wheelbarrow no access for deliveries around back






Shuttering installed and roadstone leveled and compacted







DPM layed then it snowed bloody typical! worried about laying concrete in such cold conditions but took advice from builders merchant where I got ballast and cement from, used additive to help cure the mix and went for it, especially as the mixer had to go back at the end of the week.






Layed the slab in three sections outer two first then filled in centre section
using outer slabs as reference to get centre level as best as possible






Took 4 days hard work to get base down in freezing conditions but it
turned out ok (worried a lot about the possibility of it cracking or the
surface finish flaking badly)






Concrete blocks for part retaining wall along the two back edges but also for keeping timber frame well away from damp thanks to Mike Garnham
and other who answered my question and gave advise last year when I was at the planning stage






Not a very good builder so brought one of those Marshall Bricky tools
you usually see advertised on shopping channels works really well and
surprised how good results and finish I got. spent a lot of time measuring and double checking everything square and level






Timber arrives Yeh!






When I was building the wall I inserted 10mm threaded rods between the blocks to anchor the frame too (Tommy Walshs ultimate workshop?) strip of polythene DPC between blocks and 4x2 timber drilled and bolted down






Tried to base the design on 8x4 sheet material to be used in modular way
Started to build frames for wall






Bit of a shock when first put up. I mean you do a scale drawing and in your minds eye you know what 8 ft tall looks like But once the wall was up it looked massive far to big, the missus wanted to know if I was building a snooker hall in the garden!
Almost paniced at this point and reduced the height but decided to keep it as the design and plough on regardless (really glad I did)





















18mm OSB boards for roof starting to go on











Slight detour in pictures. This stand for the mitre saw was made from the concrete shuttering after it was pulled up (based on one of Norms designs)
really useful and made the joinery a lot easier to complete.






Shiplap cladding going on whilst waiting for the roof to be made waterproof (praying for no rain)






2mm torch on ashphalt underlay applied roof now watertight thank god it didn't rain for 4 days while waiting for the roofer to arrive!






Wanted to insulate with kingspan type boarding but just could not afford it
ended up using wickes loft insulation for the roof and walls (on offer 2 for 1) covering with vapour barrier then 18mm ply on the walls and 11mm OSB on the ceiling.





















Contacted the company who had fitted widows for our house couple of years earlier explained I was building the shed and asked if he had got anything suitable that were seconds/cheap. He had the widow in the picture in his shed it had been removed from one off his clients because she did not like it and wanted it replacing with a bay type window, anyway I got it complete with double glazed units for £80 which seemed a bargin very happy with it.






Started to paint interior while relatively empty.

More to follow soon


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## rileytoolworks (31 Dec 2009)

You jammy turnip! I'd pull your legs off for that shed!
Looking forward to more pictures, though I hate you already :wink: :wink: :lol:


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## rileytoolworks (31 Dec 2009)

Ooh. The censorship doesn't recognise THAT word.... :shock:


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## Max Power (31 Dec 2009)

Great looking workshop, good idea getting the shiplap tanalised.


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## Boz62 (1 Jan 2010)

Very impressed. That will make a lovely working space.

Boz


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## MikeG. (1 Jan 2010)

That's (almost) the way to do it!

To make it perfect I would have put a membrane around the outside and battened out to create an inch void behind the cladding, but that aside, this is a super shed. Have you got the door in the right place? It looks a bit tucked in behind that other shed.

Mike


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## Gordon T (1 Jan 2010)

What a project...., will you be pulling the other shed down now?

GT


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## chippy1970 (1 Jan 2010)

Is there a big sag in the ridge board or is that an optical illusion ?


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## Mike.C (1 Jan 2010)

Brilliant build =D> =D> =D> =D>

Cheers

Mike


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## mailee (1 Jan 2010)

Very nice build, nice looking shop too. It is surprising how large these shed builds look when in framework, it's only when you start moving in the machinery that you wish you had built it even bigger! Look forward to seeing it completed up and running.


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## OPJ (1 Jan 2010)

chippy1970":2jxk4et0 said:


> Is there a big sag in the ridge board or is that an optical illusion ?



That's exactly what I thought... :-k

Otherwise, it's an excellent build and it looks like it's going to be a superb workshop. If you do find it's too small, you could always build a second shed and use one as a machine shop! :wink:

Look forward to seeing the doors go on and everything finished.


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## MikeG. (1 Jan 2010)

chippy1970":28sp65s8 said:


> Is there a big sag in the ridge board or is that an optical illusion ?



I'm guessing that the walls are spreading at the top, pushed apart by the roof gently saggingt. I note from the photos that the only tie seems to be some twisted wire of some sort, which I presume is temporary. It shouldn't take much to pull the walls together, which should raise the ridge. This should be a priority.

Mike


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## Shultzy (1 Jan 2010)

Nice build, but they take their time going up eh! :lol:


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## Haldane (1 Jan 2010)

Hello

More pics but first some answers to questions

Gordon - yes the old concrete slab garage will be coming down
but not until another small shed is made for the few items left in it gardening tools etc.. Have already made one concession in having 
the tumble dryer in the workshop (only because it needs electricty)
I have now put my foot down with a firm hand, drawn a line in the sand
and locked the doors to any other non workshop type equipment.

Chippy OPG and Mike - Yes there is a sag in the roof. When the framed walls were finished there was a couple of inch bow in the centre, I used the galvanized wire with fence tensioning adjusters to pull the wall into the the correct distance (well spotted Mike). The sag did not occur until the 18mm OSB was put on, I just assumed that the sag was caused by a combination of my poor joinery and the fact I'd used 4x2 for the ridge board (with hindsight I think something more substantial should have been used over such a long span (6m) 6x2 maybe? Plus compression from the shear weight of material in the roof. Total of 20 OSB boards inside and out and the ashphalt roofing material 2mm underlay and the 4mm gritted top sheet (struggled to lift just one roll and my own). When the roof had it's final covering torched on there were 2 of us working up there and if felt rock solid. I think the sag looks worse than it is there is only 2 1/2" drop in the centre of the entire span, might try putting some more tension in the cable as I have not touched it since the roof went on and see if it improves things.






More painting
















Electrics starting to go in. Two ring main circuits from the main board the return cable in its own plastic conduit (should make it simple to insert any further sockets if needed)






Flooring starting to go down 1" polystyrene sheets straight onto the concrete then 18mm T&G chipboard flooring boards





















You can see a vent just the left of door, there is also a bathroom type expel air unit fitted at the top of the wall to the left of the window (another of Mike Garnhams suggestions)






This was then covered with 3mm hardboard nailed at about 6" centre to hold everything in place











Electrics finally wired up with some circuits to spare (one has a 16amp breaker just in case one day I might be able to get a decent tablesaw)






Doors under construction











Due to an upgrade to Windows 7 I seem to have missplaced some photos
will post more as soon as I find them again


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## MikeG. (1 Jan 2010)

Firstly, the ridgeboard in this roof is non-structural, and has no great influence on whether the ridge sags or not. I bet if you measure the distance between the walls at plate level you will find that your shed is wider in the middle than at the ends!

Personally, I would replace/ augment your single wire-tie. I have done wire ties, and they can work beautifully (I saw a chain used as a tie in an ancient Venitian cathedral, once)........but I don't think I would ever have just one. This puts an awful lot of strain on your roof-plates, as well as being potentially disasterous if the single tie is snapped or damaged. You might consider a couple more wire ties , or a couple of say 10mm steel rods with threaded ends (cheapest way is to weld some threaded rod onto each end) with big spreader plate washers. Crank the nuts up until the walls are parallel!!!

Actually, other than aesthetically, there is no problem with stabilising your building with a sagging roof, so long as you can tolerate not-quite-straight walls, and so long as it doesn't sag any further. But I would still add some more ties.

I'm heartened to see the ventilation set-up (although it would have been better to have the Expelair on the wall opposite the door & vent).......and once the initial drying-out has finished (from the concrete, and the paint.......as well the sweat of your brow!!) I'll be interested to see if you need it. I don't anymore in mine, but it is great to know it's there if you do need it.

Incidentally, you have created a quality building that could easily be converted to a home office. When you come to sell, this can be quite a selling point, depending on the location of your house.

Mike


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## DeanN (1 Jan 2010)

Would you mind me asking what the materials cost, to-date, has been? A new shed/workshop is on the cards for this year, and I'm considering building rather than buying.


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## Haldane (1 Jan 2010)

These are only rough figures from memory 

Base materials, ballast cement roadstone £700.00
Timber inc sheet materials £1400.00
Electrics materials only £400.00
Roofing felt and laying £500.00

Total approx £3000.00
plus a lot a trips to wickes and DIY sheds for for those little things you
forget another £7/800 (propably more but I don't like to think about it to much)

I did look at kit type sheds but they were nowhere near the quality of what I think I've ended up with. Plus the fun, enjoyment and satisfaction of making it yourself

Hope this helps
Dave


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## chippy1970 (1 Jan 2010)

Dave hope you dont mind me just telling you negative things but if I dont say anything you wont learn......

Have you ever laid any flooring before ? as it looks like you have laid the chipboard flooring totally wrong in your pictures, you have not staggered your joints this makes the floor quiet weak you should have staggered the cross joints by at least 500mm but you have lined them all up.


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## chippy1970 (2 Jan 2010)

Mike Garnham":1kdpbei9 said:


> Firstly, the ridgeboard in this roof is non-structural,
> Mike



No ridgeboard is non structural they all do a job if Dave had used a deeper ridgeboard supported at both ends it would have lessened the sag but as you say he can use wire cross ties to maybe pull the walls back in.


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## MikeG. (2 Jan 2010)

chippy1970":38irvdrq said:


> Mike Garnham":38irvdrq said:
> 
> 
> > Firstly, the ridgeboard in this roof is non-structural,
> ...



No, I'm right. Most of them do a non-structural job. They are much more of a locating device and are not counted in the roof calculations unless they span, and take the entire weight of the roof. A structural ridge beam (or ridge purlin), is normally a huge piece of something.........glulam, parallam, steel etc. 

If they were structural, scarf joints would not be allowed, and no spec. for a cut roof ever excludes joints (except for fully engineered structural ridge purlins). Incidentally, trussed rooves, and most ancient oak pegged rooves, have no ridge board.

To think that a typical ridgeboard is a structural member is to fundamentally misunderstand where the forces in a roof are going.

Mike


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## MikeG. (2 Jan 2010)

........in fact, in a normal cut roof with rafters, joists and diagonal bracing, you could go along with a hand-saw after the roof was built and cut through the ridgeboard between each pair of rafters, and it wouldn't make any difference to the roof whatsoever. Once the roof is finished, a ridgeboards sole job is as part of the bracing.

Mike


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## DeanN (2 Jan 2010)

Haldane":3ulsp070 said:


> These are only rough figures from memory
> 
> Base materials, ballast cement roadstone £700.00
> Timber inc sheet materials £1400.00
> ...



Appreciate that. The figures may appear expensive compared to "flat pack" sheds, but I bet yours will outlast most. Thanks again.


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## ninjabika (2 Jan 2010)

hi

can you tell me what size this building is please ??

martin


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## MikeG. (2 Jan 2010)

Martin,

I reckon it is roughly 3.8m x 6.0m (12'-6" x 20'), but if you want exact measurements you'll have to wait for Haldane.

Mike


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## ninjabika (2 Jan 2010)

Mike Garnham":2zpdk5ot said:


> Martin,
> 
> I reckon it is roughly 3.8m x 6.0m (12'-6" x 20'), but if you want exact measurements you'll have to wait for Haldane.
> 
> Mike



mike that's fine, just looking at his rough costings so i've got something to compare against, seeing as i intend to build 6.00x3.00 (20 x 10) this year , well as soon as really


martin


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## TheTiddles (2 Jan 2010)

Mike Garnham":2uzbx9ev said:


> ........in fact, in a normal cut roof with rafters, joists and diagonal bracing, you could go along with a hand-saw after the roof was built and cut through the ridgeboard between each pair of rafters, and it wouldn't make any difference to the roof whatsoever. Once the roof is finished, a ridgeboards sole job is as part of the bracing.
> 
> Mike



Now I've looked harder I can see the sag and I'd be pretty worried if it was my shed. The ridgeboard ought to be non-loadbearing, however in this design it is and clearly isn't strong enough, with the ties holding the walls together it will remove the load on the ridgeboard and place the trusses back into compression, interesting design to not have cross-ties or whatever those thingys are called you usually lay the floorboards on in the loft isn't it?

Aidan


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## MikeG. (2 Jan 2010)

Aidan,

it does have a tie.......but only one. This type of tie is perfectly good enough, but there isn't enough of them here, and I have seen no detail of how the tie links to the plate. Two additional ties like the one already in situ, (or the alternative I also suggested), and the plates would be pulled back to where they should be, and the non-structural ridge can go back to doing its job.........ie nothing at all!

Mike


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## TheTiddles (2 Jan 2010)

Mike Garnham":1bphp1yy said:


> Aidan,
> 
> it does have a tie.......but only one. This type of tie is perfectly good enough, but there isn't enough of them here, and I have seen no detail of how the tie links to the plate. Two additional ties like the one already in situ, (or the alternative I also suggested), and the plates would be pulled back to where they should be, and the non-structural ridge can go back to doing its job.........ie nothing at all!
> 
> Mike



I didn't count that one as a "proper" tie, 1" steel rod with hydraulic rams is more my thing

Aidan


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## Haldane (3 Jan 2010)

Hi All

Answers to questions

Chippy- regarding the floor I did think about staggering the joints between the boards but then thought, seeing as its a floating floor and would have no voids and the polystyrene would be giving support in all areas it wasn't going to make much difference and would save me cutting boards up (did try to make sure the chipboard and polystyrene joints were always at right angles) Hope I don't regret that decision in future!

Ninjabika- Mike was spot on with the size 6x3.8m

I found the rest of the photo's on the computer today but it won't let me open them stating "file type not supported" these pictures were taken on the same camera as all the others and downloaded in the same way, have checked the properties of the pics and they are the same file type as the others that will open :? just don't understand computer sometimes suspect they have been corrupted somehow. :x 

So took some more this morning to finish thread off.
It's just a quick tour of where I am now

















It was just a little below freezing when I took these this morning and it had been snowing in the night. There is still some trim to finish on the outside and some dripboards? above the doors wouldn't go amiss.






View of the shed as you walk in, have been leaving a small oil filled radiator on low all night which works a lot better than I thought 12 degrees centigrade when you walk in not toasting hot but warm enough to work without a coat 






Doors have been located slightly off centre this allows 8x4 sheet materials to be stored upright against wall without getting in way.






Spur shelving for timber storage will accommodate 8' lengths longer on the top row as you can go onto the tops of the cabinets. Sliding mitre saw set into middle of worktop allows up to 8' length of timber each side, the wooden bin at the end under the cabinet is for off cut storage.






I made the wall cabinets from 18mm ply and hung them on french cleats? so they can be taken down/rearranged easily if needed.






The tool cabinet came off the wall in the old garage so doesn't quite fit will replace with something that fits better when get time






Woodturning tools and extractor fan to keep humidity down (not been needed as yet)






Lathe and compressor






Pillar drill, tablesaw, bandsaw there is also a small planner/thicknesser behind them somewhere and chip collector on wall.
he frame standing against the wall fits onto the workbench in the centre allowing you to cut large sheet material with circular saw to get them into more manageable sized pieces






All of the machines are on castors and can be pulled out to work on with plenty of space around them.

Still plenty more to do, doors on the cabinets better flooring (hardboard is a bit slippy may put vinyl tiles or safety paint down) But I think i'll live with it for a while now and try to get some projects made.

Hope you enjoyed the pictures

Dave


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## johnjin (3 Jan 2010)

Many thanks Dave
I have enjoyed the thread enormously.
These workshop threads are always so instructive,
I will hopefully start mine soon

John


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## OPJ (3 Jan 2010)

Ignoring the washing machine, that looks like a great workshop! Now, it's time to get some projects done and upload the photos... 

How are your turning tools hanging on the racks? I can see hooks in a couple of them. Are they all like that?

Many of us would kill for 12° working temperature at the minute!! :wink:


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## MickCheese (3 Jan 2010)

Can you get the hardboard up?

You could just flip it over so the rough side is uppermost as a temporary measure.

Slippery floors are not good especially when covered in fine dust.

Mick


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## TrimTheKing (4 Jan 2010)

Just cover the ramaining floor area in that rubber matting. That's what I've done, costs buttons for that amount of space, kind on the feet (and dropped toolage), easy to clean and save you any messing around with painting or ripping up flooring.

Simples


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## WoodnDesign (5 Jan 2010)

Wow.. What an excellent workshop, well designed and built, and now finished, well equipped.. what next.. :lol: ... Time for turning...

Regards. David.


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## dh7892 (8 Jan 2010)

Fantastic build. I'm really glad this is on here as it's almost the exact size that I'm hoping to build!

I have a question though: You have the damp-proof membrane under the concrete and a DPC between the blocks and the wood but isn't rain going to try to soak in between the edge of the membrane and the slab?


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## Haldane (8 Jan 2010)

dh7892
Now you mention it, I think the rain will get between the slab base and the DPM I'm thinking it should not be to much of an issue, the DPM will stop moisture being constantly drawn up into the concrete from below. I think any trapped rainwater will dry out and not cause to much of a problem. However when the weather picks up I still have plenty of odd jobs to finish one of the first will be to tidy up the edge of the DPM

Dave


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## MikeG. (8 Jan 2010)

This is the very reason why I always say leave the top edge of the concrete about 50mm above ground level. This arrangement will dry out any of the trapped rainfall which comes into contact with the edge of the concrete. The DPM is to prevent groundwater under the slab keeping the slab constantly wet.

Mike


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## dh7892 (8 Jan 2010)

That sounds fair enough thanks for the reply.

So why does the stud wall want a vapour barrier but not the blockwork? 

If there needs to be a DPC between the blockwork and the timber then that must imply that the blockwork might get damp right? Is that not going to be a problem inside since it's a single skin wall? 

Sorry if I'm being daft, just wanna make sure I get my ideas straight for when I try my luck.


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## OldSchoolTools (8 Jan 2010)

FANTASTIC, what have you got in the way of heating? something I thought about last summer and did nothing about? wish I had of.


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## Haldane (9 Jan 2010)

Hi Dh
To be honest I don't think is was strictly necessary to put a vapour barrier on as the 18mm ply would probably do the job just as well, likewise with the DPC between the blockwork and timber the blockwork is high enough to keep the timber frame well away from any damp. But the 2 items together only cost about £20 and its the correct convention? for the minimal cost it didn't seem worth not doing it.

OldSchoolTool
Heating. At first I was using a Fireray propane type heater which warms the shed in no time but originally I had this to use in a drafty garage where it was fine, I now understand why it warns you not to use them indoors as the fumes give you headache as was the case in the new well insulated and draft proof shed. I now have 2 small oil filled electric radiators I have been leaving one on low all the time even during this bad weather it keeps the shed at a steady 50 degrees and use the second one for a boost when i'm in there but usually end up turning it off after an hour as it gets to warm when you're working 

Dave


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## MikeG. (9 Jan 2010)

dh7892":2e5am7ze said:


> So why does the stud wall want a vapour barrier but not the blockwork?
> 
> If there needs to be a DPC between the blockwork and the timber then that must imply that the blockwork might get damp right? Is that not going to be a problem inside since it's a single skin wall?



Remember that this isn't a house. The moisture in the inside of a shed is not comparable with a house.....think kitchen, baths, showers, washing machines etc. The danger with moisture and a timber frame is that condensation will occur within the structure.........hence the need to keep things dry by isolating the frame from the moisture source. This isn't an issue with masonry.

There isn't a huge need for the DPC under the frame............it must be included, but it is a bit belt & braces. The taller the plinth, the less the DPC is doing. Don't forget that bricks work by absorbing moisture and then releasing it slowly (which is one reason not to use the sealants sold for waterproofing brickwork).

Mike


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## chipchaser (9 Jan 2010)

Excellent shed Dave. Good deal on the window and nice to see it being put to good use rather than going into landfill. If anyone in the Coventry area is looking for a shed window there is a firm who have recovered or misfit uPVC windows for sale. They are on the road from Toolstation towards the M6. Have not checked any prices or details but maybe worth looking?

Mike is right about the ties needed to resist outward thrust of the rafters. If it is now difficult to install ties with spreaders and nuts on the outside, several of your wire ties with fixing points coach screwed to the inside of the wall plate can work as well as a couple of more substantial ties. Obviously eye bolts through the plate with a good square washer and nut on the outside would be better if that is possible.

Have you tried opening your “lost” pictures with Irfanview? I had a trojan attack my hard drive last year but luckily recovered a lot of my files using Recuva. Irfanview opens many, but not all, of the photos which Windows Picture Viewer won’t open. I can then re-save them as .jpg in the same folder after which Windows will open them.

Regards

Graham


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## dh7892 (10 Jan 2010)

Dave and Mike,

Thanks again for the replies. So the aim is to deal with letting water vapour leave the shed, not because of any worry about watter getting into the shed. 

So there's no problem with a single skin of blockwork wicking enough water through from the elements to, say, damage the paintwork on the inside?


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## Haldane (11 Jan 2010)

Hi dh7892

Sorry can't help anymore I'm no expert and nearly all the info I needed for the shed build came from members of the forum. Hope someone (mike) may be along shortly and help out with an definitive answer

Dave


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## chipchaser (13 Jan 2010)

Hi dh,
Mike has answered the question in general terms. To get a better understanding of your situation and to comment usefully needs a bit more info:

1) What sort of blocks (dense concrete or lightweight like Celcon or Thermalite or another type) and how thick?
2) Internal and external finishes, if any?
3) I think you said single skin of block with no insulation or external lining at present, do you intend to add an internal lining or external cladding?
4) Workshop or storage?
5) Anything in the shed that produces water vapour e.g. an unvented washing dryer?

Regards
Graham


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## dh7892 (14 Jan 2010)

I'm only at the very early planning stage but, since this build as almost exactly the size I have earmarked for mine and would suit me fine in almost every respect, I was going to pretty much copy it. 

I would only be having wood working stuff in it (no tumble drier). I have no idea of what sort of blocks I would use. I was just going to go with something similar to Dave's build. 

My only question though was about the fact that the blockwork had no cladding on it and I wondered if water would wick in and cause problems. I'm sure it is fine or Mike would have said something. 

Anyway, I don't want to hijack the thread. It's a great build! I hope I can end up with somethign similar.


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## MikeG. (14 Jan 2010)

DH,

Use bricks instead. Aesthetically more pleasing, and perfectly simple to lay. You only need 2 courses. One of the keys to success is to have the slab about 50mm above ground level min., all round, and then have you render or cladding overhang the junction. This will actually mean that very little water will ever make any contact with the masonry plinth, be it brick or block. 

Don't forget, your timber frame comes flush with the outside of the bricks/ blocks, then breather membrane, battens and boarding, meaning your finish overhangs. The bottom edge of your boarding or render is some 50mm outside the line of the brickwork, so all the water that runs down the walls has a good chance of dripping clear of the brickwork.

Very little moisture will rise up the edge of your concrete as it is on a membrane, and any that does has a chance of drying off because the top edge of the concrete is well above ground. So the half-brick thick wall is relatively dry from both above and below, and will dry off quickly.

I can tell it works, because in those corners of the workshop where sawdust gathers next to the bricks the sawdust always sweeps up dusty like all the rest, rather than being at all wet.

I can't stress enough......(but goodness knows I have to!!!).......what a huge difference a plinth makes. It is the difference between a temporary shed, deteriorating as soon as it is built, or workshop, there for decades.

Mike


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## dh7892 (14 Jan 2010)

As in the common or garden red house bricks? Sounds like a plan. 

Thanks for the advice. 

I like the idea of the 10mm studs cemented in the brickwork to attach the studwork to. If I'm using brick, would I get enough purchase with one brick's worth of mortar for the studs to sit in?

Is there a recommended depth for the foundations (roadstone and concrete) for such a big area. Also, would re-bar in the concrete be a good idea?

Cheers,

Dave


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## MikeG. (14 Jan 2010)

Lots of questions there DH!

I wouldn't use the studs method myself. I prefer to cast galv. steel straps into the concrete and fold them over the wall plate. Alternatively you could build them in under the brickwork (L shaped straps), but I would want to see at least 3 courses of bricks in that case.

As for foundations.......build it so that you dont require Buiding regs (ie small enough and away from boundaries), and you can omit foundations and just build off a slab (say 6 inch conc. Yes, in that circumstance I would put mesh in it. Don't do this if there are major tree roots through the site.......and thicken it up if you are on clay. Treat this part of the advice with caution.......investigate your site circumstances before designing a slab/ foundation.

Mike


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## dh7892 (15 Jan 2010)

Thanks,

I think I'm going to need both permission and regs as I need to be up close to a fence and I want more than 15 sq m.


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## Woody Alan (15 Jan 2010)

Mike,

I have built a couple of buildings that I took straight off a slab.
here's one










I have since moved and will be doing something similar. I have a question about your preferred method of a couple of courses of brick. How do you make good and insulate tidily on the inside of the building or do you accept a cold bridge? and do you have to frame in 4" so as to span the brick? but that still gives a cold bridge at the base.

Cheers Alan I need to get the next one right


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## MikeG. (17 Jan 2010)

Alan,

yes, I just accept the cold bridge. Given the occasional heating and low moisture-production in a typical workshop it cause no problems at all. Having said that, there are a number of ways in which you could insulate the inside of the plinth if you really wanted to, such as by overhanging the frame an inch inside the brickwork, placing an inch of Kingspan inside the bricks, then bringing the inner skin of sheathing board down to the slab.

You don't have to frame in 4", but for that size of building I would be uncomfortable seeing it built of 3x2s, and don't really see what you would gain. You could use 5x2s, and thereby create the overhang I spoke of allowing insulation of the plinth, but it seems to me that might be an expensive sledgehammer to crack a very unimportant nut.

It is a pity you put such a lot of effort into this workhop and still ended up with something you aren't completely happy with.

Mike


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## jack55 (17 Jan 2010)

Nice workshop build I like a few others it seems are planning a similar build in the summer. The roof design gives lots of head room and I would like to do the same. Would that design work on a 14 foot wide by 18 foot long shed? and are the metal rope ties the only way of stopping the walls spreading.

Link to big picture


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## MikeG. (17 Jan 2010)

Jack, 

it would be nice if you could re-size that drawing to make it 800 wide so that we don't have to scroll sideways to see it all.

There are lots of ways of doing rooves. You appear to be showing a post at the gable to support the ridge......and if you have a substantial structural ridge beam, calculated to support all of the roof-loads , then you won't need any ties to prevent the roof spreading. However, this relies on an 18 foot long piece of something......probably a glulam beam or composite "I" beam, even a flitch beam (steel & timber).....that doesn't deflect under the imposed load.

You could do old-fashioned Principal trusses with intermediate common rafters supported on purlins and even a ridge purlin.........meaning that you wouldn't need any ties. You would probably be best with just one central principal truss.

The simpler and cheaper way is to tie across at roof-plate level. This doesn't need to be at each rafter, and with a substantial and continuous roof-plate you might be able to only use a couple of ties in 18 feet. This tie could be tensioned wire, but it is probably better in steel rod or timber.

The other thing to consider is having ties at every rafter, but have them raised (collars/ raised ties). Typically they work best around one third of the way up the rafters. You could combine raised ties with purlins, so that you didn't have to have ties at each rafter.

I would stress that none of this is to be done by guesswork. Whatever you propose should be checked by someone competent. I'm not a structural engineer, so if you require building regs for this then I am not qualified to prove the structure. However, if it doesn't require BR approval, then I can design the roof for you without any problems.

I hope this helps.

Mike


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## jack55 (19 Jan 2010)

Thanks for the offer Mike. I will put in the form to see if I need BR, going to keep it within the 2.5 eaves height and overall less than 4 with 1.5m from the boundary wall and see what they say. SWMBO's greenhouse roof suffered from the weight of the snow which bent the roof ridge beam and the support bars. Although a lot lighter it is a similar design. Forgot about the drawing width my comp screen is 22" so it all shows on this.


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