# Advice needed please on building a small wood workshop



## Joe1975 (1 Jan 2023)

I would really like to have somewhere dedicated to woodworking. There is space for a 16”x8” workshop at the end of the garden. I have a week back (herniated disc) from a previous build so need to keep the physical workload down to a minimum. With my back and the site being so far from the road I don’t want a concrete base, or even footings if I can avoid. The site is about 2’ of topsoil on a chalk bed, it is level. The build will need to be below 2.5m in height.

I have a small amount of power (effectively a 13amp socket) to power the workshop so will have to be mindful of this. I have a bandsaw and may well purchase a small table saw, pillar drill, and a thicknesser at some stage, but am mostly interested in building small pieces by hand.

I need to make sure that the workshop can maintain a dry environment - it will obviously store my wood and my tools. I guess I need some insulation and double glazing for this. 

Any details on what footing/ground support would be the easiest and cheapest would be helpful. At the moment I’m thinking of digging down to hardish soil, putting a bit of hardcore in, and using stacks of heavy concrete blocks (maybe three) to about 4” above the surface. I would probably use 15 pillars on 4ft centre’s.

What’s the cheapest way to insulate the whole workshop? I want to keep the whole build down to 5-6k.

Any design thoughts especially with regards to insulation and damp avoidance would be greatly appreciated.


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## Mel769 (1 Jan 2023)

Celotex insulation between studs perhaps ? Fairly cheap and available.


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## Jameshow (1 Jan 2023)

2 Concrete blocks laid flat with another at right angles would spread the load amply on normal soil. 

6x2 will do for 8ft spans. 

3x2 studs with 2" insulation foil facing inwards and taped. Fabric to outside, batten and cladding 

Roof epm / fibreglass pro team.


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## Ttrees (1 Jan 2023)

Will Joe not have to use some form of DPM
I've been thinking the same thing with the blocks on some stone,
and it wouldn't be seen as such a permanent thing, and could be movable and cheaply adaptable
solution.
Is there a type of plastic one can do something with instead of buying a roll?


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## Jameshow (1 Jan 2023)

Best to use something Dpm under the joists or bitumen paint painted on??


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## BucksDad (1 Jan 2023)

Is it a house for life? If so could consider getting plastic joists and never having to worry about it again


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## Daniel2 (1 Jan 2023)

16" x 8" is quite small by workshop standards


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## Fitzroy (1 Jan 2023)

I built a workshop on pier foundations to avoid too much potential damage to a tree root zone. The downside is height, piers finish 10cm above soil level, then with a 150mm frame you are 250mm above ground already. Place a 150mm roof on that and you’re limited to low ceilings to stay inside permitted dev rights and your 2.5m limit. For these reasons I applied for planning, was easy to do a cost about £250 and I could build what I wanted. 

Damp avoidance is about good overhangs and proper wall design. See how to build a shed mikes way sticky. It’s about structure wrapped in a membrane, then with cladding to keep the rain off. 

If you plan to insulate then put it in the design, don’t try to add as an afterthought. I think the easiest and most cost effective is 4x2 framework with Rockwool in between studs. Kingspan has better insulation values but is more expensive and harder to do a good job with. I’ve just finished insulating mine with 100mm Rockwool and an hour with the fan heater on took it from 5degC to a usable 12degC. Then with just me working in there the temperature would increase to 14-16degC and I’d have to crack the door to avoid getting sweaty. 

I’ve ran my shed on a 13A extension lead for the last 5 yrs it’ll do any of my tools and the lights happily. No I don’t endorse this is a permanent solution, proper electrics are on the list. I have to turn the fan heater off if I’m starting a big machine else it can pop the fuse, and sometimes the cable will steam in the damp grass on a cold morning, but you pay your money and make your choice. 

If you are doing the build yourself I think £5-6k is plenty for your size of building. Mine was about £3k but timber has gone through the roof since then!

Look out for free double glazed windows on gumtree and design around them to save money. 

My full build is on here as a post, it’s getting a bit dated now though, especially on costs.


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## Molynoox (2 Jan 2023)

-PIR the best insulation but not the cheapest. PIR horrible to work with also
-4x2 the de facto standard for walls but 3x2 can also work if you can compromise on insulation thickness
-Pier foundations the cheapest option but you will need to excavate down first if staying under the 2.5m limit
-EPDM a no brainer option for roof imo
-Source cheap 2nd hand door and window and build walls around it - as others have mentioned

Check out ali dymok YouTube for pier foundations, and read build threads on here to get other ideas
Also, do a build thread on here and ask questions as you go

Martin


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## Dave Moore (2 Jan 2023)

You can get ground screws which can be used for piers then insulate the floor.https://pin.it/1hutyvN


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## Joe1975 (2 Jan 2023)

Jameshow said:


> 2 Concrete blocks laid flat with another at right angles would spread the load amply on normal soil.
> 
> 6x2 will do for 8ft spans.
> 
> ...



Concrete blocks  
4’ centres on blocks so I think 5x2s will be fine
Happy to use 4x2 for framing
2” insulation seems to be a good compromise between cost and performance  Doesn’t PIR have foil on both sides?
Fabric, batten, and cladding (ie 12mm OSB board inside only)  
EPDM Roof 

Thanks for the advice.


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## Joe1975 (2 Jan 2023)

Ttrees said:


> Will Joe not have to use some form of DPM
> I've been thinking the same thing with the blocks on some stone,
> and it wouldn't be seen as such a permanent thing, and could be movable and cheaply adaptable
> solution.
> Is there a type of plastic one can do something with instead of buying a roll?


Thank you, I had to buy a roll of DPM for another project so will use that to protect timbers at point of contact, maybe bitumen paint would be belt and braces. It’s possible damp leaves may accumulate underneath.


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## Joe1975 (2 Jan 2023)

Jameshow said:


> Best to use something Dpm under the joists or bitumen paint painted on??


Will do, thanks


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## Joe1975 (2 Jan 2023)

BucksDad said:


> Is it a house for life? If so could consider getting plastic joists and never having to worry about it again


House for at least another 10yrs, but I want it to last. I think treated 5x2 timber that are not exposed directly to moisture should last a while, don’t you?


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## Joe1975 (2 Jan 2023)

Daniel2 said:


> 16" x 8" is quite small by workshop standards


Yes, one end will be a workbench, with a tool cabinet on the wall. The other end will be for a bandsaw, small table saw, and wood storage. Of course it would be nice to have more space, if things get serious I will need more power as well.


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## Joe1975 (2 Jan 2023)

Fitzroy said:


> I built a workshop on pier foundations to avoid too much potential damage to a tree root zone. The downside is height, piers finish 10cm above soil level, then with a 150mm frame you are 250mm above ground already. Place a 150mm roof on that and you’re limited to low ceilings to stay inside permitted dev rights and your 2.5m limit. For these reasons I applied for planning, was easy to do a cost about £250 and I could build what I wanted.
> 
> Damp avoidance is about good overhangs and proper wall design. See how to build a shed mikes way sticky. It’s about structure wrapped in a membrane, then with cladding to keep the rain off.
> 
> ...


Thank you. Did you not use OSB on the outside of the studs as well as the inside? 
Is the breathable membrane (TYVEK Housewrap) strong enough to hold in the rock wool?
It sounds as though the rock wool works well.
I will look out for secondhand windows and door.


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## Joe1975 (2 Jan 2023)

Molynoox said:


> -PIR the best insulation but not the cheapest. PIR horrible to work with also
> -4x2 the de facto standard for walls but 3x2 can also work if you can compromise on insulation thickness
> -Pier foundations the cheapest option but you will need to excavate down first if staying under the 2.5m limit
> -EPDM a no brainer option for roof imo
> ...


Thank you, Ali Dymock’s series is very thorough but a bit higher spec than I was planning for this build. Trying to work out where I can reasonably cut corners and expenses.


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## HOJ (2 Jan 2023)

Daniel2 said:


> 16" x 8" is quite small by workshop standards


Doll's houses are bigger!!


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## Jameshow (2 Jan 2023)

HOJ said:


> Doll's houses are bigger!!


" = Inches
' = Feet.


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## Fitzroy (2 Jan 2023)

I have OSB outside the studs, it is not ideal with an insulated structure as you risk a condensation trap. However the Canadians will tell you they’ve done it that way forever.

I’d not thought about if externally just having house wrap would hold the Rockwool adequately. With the battening you’ll require for the external cladding the house wrap is held pretty tight and it’s pretty robust fabric so I’d say it’ll be fine. The Rockwool slabs have quite a bit of structure to them.


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## Mel769 (2 Jan 2023)

I built my shed from old doors and free timber found in skips ect about 15 years ago and its still standing. Almost all the timber was salvaged (incl the featheredge. Floor was 4x2's on cast concrete padstones with some dpm on the ends. Decided on a green roof and its not leaked (yet). See the photos below


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## Molynoox (2 Jan 2023)

Joe1975 said:


> Thank you, Ali Dymock’s series is very thorough but a bit higher spec than I was planning for this build. Trying to work out where I can reasonably cut corners and expenses.


i referenced ali dymok just for the piers


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## Daniel2 (2 Jan 2023)

Joe1975 said:


> Yes, one end will be a workbench, with a tool cabinet on the wall. The other end will be for a bandsaw, small table saw, and wood storage. Of course it would be nice to have more space, if things get serious I will need more power as well.



I was pulling your leg 
It sounds a reasonable size.
But " represents inches & ' represents feet. 
Good luck with the build. 

ETA: I see @Jameshow beat me to it.


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## Jameshow (2 Jan 2023)

Mel769 said:


> I built my shed from old doors and free timber found in skips ect about 15 years ago and its still standing. Almost all the timber was salvaged (incl the featheredge. Floor was 4x2's on cast concrete padstones with some dpm on the ends. Decided on a green roof and its not leaked (yet). See the photos below


Pretty cool!!


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## Mel769 (2 Jan 2023)

Jameshow said:


> Pretty cool!!


Thanks, thought id show for the original poser really, for insulation we used thin (20mm or there abouts) celotex wedged between battens screwed to the doors (walls) on the inside, and then plasterboard. Had no issues with damp atall. However the floor tends to get a bit damp only when it snows, not sure why this is ? The floor is made up of doors above the joists with floorboards above the doors, its odd as when it snows (and only when the snow has settled) I can see rising damp along the edges of each floor board; its fine in all other weathers.


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## Jameshow (2 Jan 2023)

Mel769 said:


> Thanks, thought id show for the original poser really, for insulation we used thin (20mm or there abouts) celotex wedged between battens screwed to the doors (walls) on the inside, and then plasterboard. Had no issues with damp atall. However the floor tends to get a bit damp only when it snows, not sure why this is ? The floor is made up of doors above the joists with floorboards above the doors, its odd as when it snows (and only when the snow has settled) I can see rising damp along the edges of each floor board; its fine in all other weathers.


Your probably leaving the door open!


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## Joe1975 (2 Jan 2023)

Daniel2 said:


> 16" x 8" is quite small by workshop standards


Okay, got it now!


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## Joe1975 (2 Jan 2023)

Jameshow said:


> " = Inches
> ' = Feet.


Thank you, got it now!


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## Joe1975 (2 Jan 2023)

This is the plan at the moment. Any comments?

Is it worth putting a vapour barrier (plastic sheet) between the floor joints and the plywood? And run it up the outside of the bottom 4x2.

NB: The weed barrier would go between the blocks (not as shown). Also just noticed I haven’t drawn the OSB extending over the bottom 4x2.

Not sure how to do windows and doors, or flat roof yet.


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## Joe1975 (2 Jan 2023)

Can you get away without joist hangers for the floor?


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## John Brown (2 Jan 2023)

Joe1975 said:


> Can you get away without joist hangers for the floor?


I don't know, but I can tell you that nailing in the joist hangers for the floor was an extremely boring task!

I somehow ordered about three times too many galvanized nails for my joist hangers, the surplus of which you are welcome to if ever passing my way (GL11)


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## Molynoox (3 Jan 2023)

Joe1975 said:


> View attachment 150353
> 
> This is the plan at the moment. Any comments?
> 
> ...


Looks good 
I would consider 22mm chipboard instead of ply for the floor, this is more common
You could put rodent mesh at interface of base and ground
My only concern with your plan would be your foundations, how much hardcore are you putting under those blocks?
Also I haven't seen your roof design yet, it's easy to get that wrong - I would recommend a similar diagram for that 

Martin


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## Mr Christopher (3 Jan 2023)

On our build we used Rockwool slabs. After building the frame we wrapped with breathable membrane and fitted the exterior weatherboard. Then in went the insulation before finally finishing the inside with 11mm OSB.


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## jcassidy (3 Jan 2023)

So one thing i did to cut costs is use pallet wood for the interior and exterior cladding. On the inside, just nailed on, for the outside I T&G'ed the wood.

I also lucked out by getting a van full of expanded polysytrene foam insulation from a demolition site, so I only used expensive foil-backed foam for roof and underfloor.

My workshop is 16' by 6'!


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## HamsterJam (3 Jan 2023)

I’ve just built a 3x4m log cabin to use as a workshop. It is on a concrete slab which I got a local builder to put down for me although it could have gone down on anything resembling a patio as long as it’s flat. 
It has 40mm thick walls and double glazed doors/window. I added 50mm PIR between the roof and the felt shingles and same under a chipboard floor on top of a DPM. 
Total cost excluding electrics was comfortably within your budget and it is an easy build once the base is down. 
This one is fed via a 40A breaker off the main house board but I built similar at our previous house and that was fed from one 13A socket. I use a 1.5kW oil filled radiator on frost setting and have not had a corrosion or condensation issue.


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## Joe1975 (3 Jan 2023)

Molynoox said:


> Looks good
> I would consider 22mm chipboard instead of ply for the floor, this is more common
> You could put rodent mesh at interface of base and ground
> My only concern with your plan would be your foundations, how much hardcore are you putting under those blocks?
> ...


Thank you Martin it’s very reassuring to get someone else’s view, is chipboard as strong and water resistant as plywood?
I will draw up another diagram for the roof when I’ve given it more thought.
I would dig down to reasonably hard soil and use 4-6” of hardcore.


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## Jameshow (3 Jan 2023)

Joe1975 said:


> Thank you Martin it’s very reassuring to get someone else’s view, is chipboard as strong and water resistant as plywood?
> I will draw up another diagram for the roof when I’ve given it more thought.
> I would dig down to reasonably hard soil and use 4-6” of hardcore.


I'd use plywood dosent urn to Weetabix if it gets damp. 

Use 18mm on 400mm joist centres.


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## John Brown (3 Jan 2023)

Why not OSB?


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## Joe1975 (3 Jan 2023)

Jameshow said:


> I'd use plywood dosent urn to Weetabix if it gets damp.
> 
> Use 18mm on 400mm joist centres.


Thank you, there do seem to be water-resistant forms of chipboard, but I am still leaning towards plywood.


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## Joe1975 (3 Jan 2023)

John Brown said:


> Why not OSB?


I want a decent surface on the floor, but am planning on OSB for walls and ceiling.


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## Molynoox (3 Jan 2023)

Joe1975 said:


> Thank you Martin it’s very reassuring to get someone else’s view, is chipboard as strong and water resistant as plywood?
> I will draw up another diagram for the roof when I’ve given it more thought.
> I would dig down to reasonably hard soil and use 4-6” of hardcore.


Seems to be three factors for the flooring material
1 strength
2 damp resistance
3 water resistance

Chipboard is strong enough... Its tongue and groove design means that once it's glued and screwed down it acts like one massive sheet. An advantage of that is you don't need to worry about finishing the board edges on the joists so you get better utilisation of the boards and also minimised cutting.

On wet and damp I wouldn't trust chipboard anywhere near water, as James mentioned, but on damp I think it's only the edges that might be at risk as the underside is usually a shiny plasticised surface that I would expect to do pretty well with normal humidity. The exception would be if you have an unusually large amount of humidity / condensation in which case you have other problems you need to solve. I think ply is probably more expensive but it's certainly an option and plenty of people use it. OSB3 too. Ply comes in lots of flavours and some are more water resistant than others so if going that route it's worth thinking about that side before buying.

On the foundations thing it's a tricky one because, as you alluded to, the ultimate factor is the soil underneath the foundations! So the fact you are aware of that and are assessing soil conditions and not just blindly throwing in 100mm of type1 on top of decayed leaf sludge is probably the most important thing  Its a judgment call at the end of the day and I think my concern was that its dependant on factors you can't really control or measure I.e. the soil 'strength'. For that reason I would be digging down a bit further than I felt it needed and adding slightly more hardcore than I felt it needed.

It's the main reason I prefer groundscrews over piers actually, but I do like the pier foundations... they are cheap and fast which are big selling points 

Martin


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## Fitzroy (3 Jan 2023)

Joe1975 said:


> I want a decent surface on the floor, but am planning on OSB for walls and ceiling.


I used 18mm ply rather than osb on a recent job as it was cheaper! Crazy world we live in.


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## Joe1975 (3 Jan 2023)

Would these be worth using to hold the hardcore at the base of the pillar ‘foundations’?


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## Colin the helper (4 Jan 2023)

Hi what I will say if you can build it to max size you will e surprised how much room you need when you start your wood projects my shop is 5m by 3m with a small 3m by 2m conservator which I use as my wood store only a cheap aluminium but cheap way for more room I have french doors in the front and a single door in the front a double glazed door on the side to go to the wood store helps with natural light hope this gives you some ideas and the more windows and doors you have the less ply or strand board you need if you go to a window and door company you can get some good secondhand doors and windows as when they remove them from houses they put it all in a skip by second hand scaffold boards rip them down and glue together cheaper than four be to as you no scaffold boards last forever pre treat them all saves money hope this helps you


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## charles79130 (4 Jan 2023)

John Brown said:


> Why not OSB?


I used osb for mine


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## John Brown (4 Jan 2023)

charles79130 said:


> I used osb for mine


Me too. On my previous even smaller shed I had 24mm(?) flooring grade ply. Luxury!


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## Joe1975 (4 Jan 2023)

Colin the helper said:


> Hi what I will say if you can build it to max size you will e surprised how much room you need when you start your wood projects my shop is 5m by 3m with a small 3m by 2m conservator which I use as my wood store only a cheap aluminium but cheap way for more room I have french doors in the front and a single door in the front a double glazed door on the side to go to the wood store helps with natural light hope this gives you some ideas and the more windows and doors you have the less ply or strand board you need if you go to a window and door company you can get some good secondhand doors and windows as when they remove them from houses they put it all in a skip by second hand scaffold boards rip them down and glue together cheaper than four be to as you no scaffold boards last forever pre treat them all saves money hope this helps you


Thanks for your advice. It’s going to look very strange if I increase its width from 2.4m. I could potentially make it a bit longer, maybe 6m instead of 4.8m.
I do have a plan if I need more space in the future.


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