Insulating wooden workshop advice

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Dreadhead

Bushcrafter through and through
Just moved house, and got me a 10x12 workshop. But I need some advice.

It's wood, has a concrete base and a new tin roof. Got lights and power installed too.
I know I need to replace some guttering and give the outside a fresh sealing with something which is straight forward.

But I need advice on how best to insulate the inside in a relatively simple and cost effective way.

I've been reading up and thinking of lining the walls with polystyrene insulation in between the studs (leaving a gap between polystyrene and outer wall), then a vapour proof layer, then cover in chip board. I've read it's good to put a breathable membrane directly into the outer wall, but as it's already built the studs are in the way, would it just be a case of cutting it into sheets and fitting between the studs?

Also need to decide on whether to insulate the top ceiling, or board up on the rafters lower down to create lower workshop with storage above it

Am I on the right track? Or missing something obvious? Im essentially out of work until I get this sorted as don't have space to work in the house right now so it's my priority

Cheers folks
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Broch

Life Member
Jan 18, 2009
7,978
7,755
Mid Wales
www.mont-hmg.co.uk
Looks like great space Hamish (but someone looks less than pleased :) )

My studio looked very similar to start with some 20 years ago. I put a lining up between the studs then fibre insulation (polystyrene will be less prone to rodents but I don't like the fire hazard). I then finished with plaster board inside but just painted it; didn't plaster. I put hardboard down on the floor, then underfelt and carpet for the 'comfy' half (a lot of cold comes through the concrete floor) but just painted concrete for the 'messy' half; I have a dividing wall and door.

I'm just about to replace the hardboard ceiling (it was cheap!) with 4mm ply - that will be topped with roof insulation and some boarding where I want storage.
I'm also going to put in a small log burner :)

However, it's nearly spring, you could delay everything till autumn if you need to get on with work. But I do appreciate it's much easier to do it all before you 'take residence' :)
 

Dreadhead

Bushcrafter through and through
Haha aye swmbo was cold and tired when we got in today.

That's braw sounds similar to what I want to do. I was thinking plywood or chip board over plaster board as it's a bit better for screwing shelves and racks into, not sure if there is any other difference between them.

I like idea of boarding on the beams just above head height and insulating that to create loft space for storage, also less space to heat underneath. Just need to check what beams are like and how viable.

I need this all done asap really so I can make it home. I practically live in my workshop so got to get the ship shape :)

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daveO

Native
Jun 22, 2009
1,453
513
South Wales
Retro fit is always a bit tricky on a budget. What you have to remember is that there is more chance of water getting into the structure and degrading the timber. Once you add insulation you can trap that water in places so ventilation within the structural studs is key to maintaining the integrity of the wood.

For a new building with timber cladding (working from outside) you would have your timber cladding boards, strips of DPC between the boards and a 50mm stud (The DPC reduces wetting of the studs and the 50mm cavity is the minimum required to prevent rain breaching the cavity). Then you would have breather paper fitted to the external face on 9mm OSB board with, usually 89mm structural studwork internally. The breather paper protects the structural stud from wetting and allows any moisture to escape back out.

If this was my workshop I would remove the cross bracings and anything else and get back to just the vertical studs. Staple a breather paper to the studs in long horizontal lengths starting from the top. Then screw OSB or ply (minimum 9mm) to the studs which will replace all that cross bracing and make the structure nice and stiff. Now you're pretty much free to do what you want inside. I would put a continous layer of insulation boards around the whole place* then fit another layer of ply, boards (or even reclaimed pallet planks) screwed through into the previous ply layer or the studs if you've made a note of where they are. If you want a lot of shelves or heavy fittings then I'd put another layer of vertical 50x50 batten internally before the ply or use an independant structure internally.

*insulation could either be polystyrene or the foil faced stuff like Celotex. Foil faced is best and 50mm would be overkill for the job but fit it tightly, fill gaps with expanding foam and tape the joints if you do use it which will give you your vapour barrier. You need about twice the thickness of polystyrene to get the same effect as Celotex but polystyrene is much more resistant to wetting so if there's a chance of damp getting in somewhere then don't waste money on foil faced boards. On jobs where I've converted these to houses we've used a breathable multi-foil insulation but it's either crap or too pricey.

I just designed the conversion of one of these into a holiday let/rural skills workshop. The planning approval very strictly stated the building had to remain and be converted as it stood. We took the whole thing down, built a brand new house on the spot and reconstructed the old building back around the outside. No one seems to have noticed :doh:
 

Broch

Life Member
Jan 18, 2009
7,978
7,755
Mid Wales
www.mont-hmg.co.uk
Now you've had the professional response; wish I'd had that before I did mine :)

Oh, just one point, while I remember, make sure you make the roof space rodent proof! Well, as near as you can anyway. The main reason for me having to replace the ceiling on my studio is that squirrels nested in the roof space and they make a real stink! :(

DaveO, you don't fancy a bushcraft weekend up in my wood when I'm building the shepherd's hut do you ;)
 
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srod

Forager
Feb 9, 2017
111
59
argyll
Simple stuff:

Insulated boilersuit!

Make sure place is dry, weatherproof and sound.

Solid fuel stove?
 
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daveO

Native
Jun 22, 2009
1,453
513
South Wales
The cheapest option actually (if you know some people and fancy some hard work) would be to use sheep wool. The proper treated stuff is expensive but straight off the farm and washed will work just as well if you fit it right. I know some smallholders can't get rid of the stuff. Wool breathes so less risk to your timberwork and you don't need vapour barriers. I'd still fit a breather membrane between the timber and insulation though just to be sure. Just fit it slack so you can stuff the wool down between the studs as you board up the inside (pallets again would work great for that). Rodents are the problem with this approach though and moths but if you get problems it should be easy enough to add more wool or replace some.

I also forgot to say that you can use a spray wood treatment on the inside of the shed before doing any work which will also help prolong the life of the timber, nothing fancy just Ronseal type stuff, and keep the cladding tidy on the outside to allow water to run off well. Keep the water moving is your mantra with timber.
 

Toddy

Mod
Mod
Jan 21, 2005
38,937
4,570
S. Lanarkshire
It's often better in a workshop to heat the person than the air around them.
Best advice if you're sitting at a bench for hours in an outside wooden workshop is to create a 'nest'. Build in a sort of wall behind you between you and the doorway to baffle the drafts and cold air. Get your feet off the floor somehow or other, duck board or padded low bench.
The Japanese traditionally sat to work with their feet in a pit, and the heater down there with them. It works and is surprisingly comfortable. I think I'd find some way to make something similar 'underbench'.

If funds are really tight, and yet the workshop is dry top and bottom and the walls are sound, you could just nail hardboard across the uprights and those rafters. It comes in 8 x 4 sheets and pins on easily just with panel pins. It creates a draught free wall space even without insulation. It's like making a room inside the walls kind of thing. Under eight quid a sheet from Wickes and the like. It makes a heck of a difference to a cold shed. Get something to heat it inside that space and it can become a very comfortable workshop very quickly indeed. It sort of breathes too, so condensation is often not an issue unlike on polystyrene sheeting, and it can be painted with the cheapest white you can find to reflect light.

If you do all that though, you'd be better not using gas or paraffin type heating in there. I know electricity is expensive, but it doesn't have condensation and that's a huge issue, especially if you have materials and tools sitting in an outside workshop. Electric oil fired heater under your bench could be very comfortable or a small storage heater.
A wood fired stove would give both heat and airflow, but it's a dirty thing with soot and the like, and it needs space around it, and it needs a chimney/flue that you can clean easily, etc., etc., Did watergypsy not have one on the boat ?

It sounds like you have potentially a great workspace Hamish :D best of luck sorting it out :cool:

M
 

Dogoak

Bushcrafter (boy, I've got a lot to say!)
Jan 24, 2009
2,285
286
Cairngorms
Can't really add anything apart from agreeing with DaveO.

Kingspan type insulation is easy to use and you can get a nice tight fit between the uprights, etc. When I was renovating our cottage I used https://www.secondsandco.co.uk good service and good prices, hope you find it useful.
 

Macaroon

A bemused & bewildered
Jan 5, 2013
7,209
362
73
SE Wales
All good advice above, but there are things to be aware of if the building is not yours or you may not have the use of it for long. It's very easy to spend a lot of dosh on this, and that's no good if you don't do a cost analysis thing in view of the length of time you'll have the use of the place. I'm just coming to the end of almost exactly the same re-furb on a slightly larger shed-type building I bought standing elsewhere and re-erected in my garden. I did walls and ceiling with 45mm Kingspan bought from the link Dogoak provides above and it worked out at about £400 to insulate the place, then another £150 to raise and insulate a timber floor. That took a lot of research and thought, not to mention time and labour, to get it done properly at that price. If you install a moisture barrier on the outside of the insulation you can double that, at least, as for it to be effective you'd have to do what daveO says and put studwork in agin the original walls; I didn't do that as I couldn't afford either the cash or the loss of space inside but what I did do was spend a few days going around the outside to weatherproof the exterior shell as efficiently as possible and keep the water moving as suggested above. I got all that finished just in time for the winter and it has remained dry and sound through the worse winter we've had here for a good while. I'm at an age now where the option of not having the whole space warm just isn't a goer for me. To line the inside I bought another shed standing and dismantled this one completely, using the exterior boards to line the interior of mine.

Something I became aware of a few workshops ago, when I went for the unnisulated model, was storage of consumables. I'd been using the shop up until mid-Autumn and went away for a couple of months; I cleaned the place up and left everything in good order for a period of absence but came back to find that the winter temperatures had destroyed all my adhesives, polishes, stains, varnishes and all the containers of things I'd made up for myself. I got a massive shock when I went to replace it all; we know it's become very expensive even when you need to buy stuff as it runs out, but I got the shock of my life at the cost of buying in a basic stock of those things. Since then I use a large shelved unit built in a hay box style with a tiny thermostatically controlled heater to keep it all at 8 degrees. Works a treat.
 

Dreadhead

Bushcrafter through and through
Thanks for the advice everyobe. I've been off grid for a while, hopefully get internet hooked up tomorrow.

So I've stripped everything back to just walls and studs. I've ordered some breathable membrane which I'll staple in between the studs as my first job.

I've noticed some big gaps around the eves. Should I leave these as they are for ventilation, or fill them? If I fill them should I use expanding foam or just some lengths of wood to plug the gaps?



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Macaroon

A bemused & bewildered
Jan 5, 2013
7,209
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SE Wales
If you can plug the gaps with scrap timber, do that; as long as the gaps are made small the pay-off is worth it as ventilation is important. As stated above if the water keeps moving it never gets damp, as long as it's not streaming into the place.
 

Dave Budd

Gold Trader
Staff member
Jan 8, 2006
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www.davebudd.com
i've been away and only just read this, but I was going to say exactly what has already been said about the membrane and celotex :)

My own dry workshop (which is where I do my leatherwork etc) was a flat pack shed of much inferior construction, but I did the same. In my case the studs were only 50mm so I lined the room with membrane and then put 45mm celotex i every gap I could find. The walls are then covered with 12mm plasterboard. In my case, the floor was the normal wooden shed flooring, but I put some 45mm celotex underneath it (I reinforced the base with OSB due to it being up on stilts by a couple of feet in places). I also put the same celotex against the roof panels and used triple walled poly carbonate sheet for my skylights. The insulation on the floor and the ceiling do at least as much good as that on the walls (and doors).

Another note is the heating. I use a wood burner, as you would expect. The room takes a while to warm up, but once the plasterboard has warmed a bit then the room stays warm for a lot longer than the burner is alight for. That is much better for controlling condensation on stuff in there and thus mould an the like on my leather! It also means that if I go in a day after I have had a few days working in there, but don't want the burner lit for a few hours, then it is still bearable :)
 

Dreadhead

Bushcrafter through and through
i've been away and only just read this, but I was going to say exactly what has already been said about the membrane and celotex :)

My own dry workshop (which is where I do my leatherwork etc) was a flat pack shed of much inferior construction, but I did the same. In my case the studs were only 50mm so I lined the room with membrane and then put 45mm celotex i every gap I could find. The walls are then covered with 12mm plasterboard. In my case, the floor was the normal wooden shed flooring, but I put some 45mm celotex underneath it (I reinforced the base with OSB due to it being up on stilts by a couple of feet in places). I also put the same celotex against the roof panels and used triple walled poly carbonate sheet for my skylights. The insulation on the floor and the ceiling do at least as much good as that on the walls (and doors).

Another note is the heating. I use a wood burner, as you would expect. The room takes a while to warm up, but once the plasterboard has warmed a bit then the room stays warm for a lot longer than the burner is alight for. That is much better for controlling condensation on stuff in there and thus mould an the like on my leather! It also means that if I go in a day after I have had a few days working in there, but don't want the burner lit for a few hours, then it is still bearable :)
Quality cheers mate good to know I'm on the right track!

The gutting continues, almost ready to staple in first layer.

Wee question for you smart folks, when I fit my polystyrene insulation in should I lay it straight against the outer wall or put some 20mm bits of wood in first to create an air gap between outer wall/membrane and the polystyrene? Seems to make sense to have an air gap
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Dogoak

Bushcrafter (boy, I've got a lot to say!)
Jan 24, 2009
2,285
286
Cairngorms
Quality cheers mate good to know I'm on the right track!

The gutting continues, almost ready to staple in first layer.

Wee question for you smart folks, when I fit my polystyrene insulation in should I lay it straight against the outer wall or put some 20mm bits of wood in first to create an air gap between outer wall/membrane and the polystyrene? Seems to make sense to have an air gap
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That's the way I'd go Hamish.
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,112
83
36
Scotland
Hamish, I've literally just ripped out all the carpets and underlay from my house. It's rolled up in the shed at the minute and will be skipped in a couple of weeks when I get ashore again. I need to keep some for the loft but you'd be more than welcome to have as much as you need if you want to put some down in there?

All the best
Andy
 

Janne

Sent off - Not allowed to play
Feb 10, 2016
12,330
2,293
Grand Cayman, Norway, Sweden
Hamish, to your question:
I would leave a small gap between the insulation, on both sides.
The outside wall of the shed is not made 100% weather proof, same with floor. I rather lose a bit heat than having a mould problem.
For insulation I would use closed cell foam type styrofoam sheets. Easy to work with, and mice will not build nests in it.

I ade and insulated a shed like this in UK about 11 years ago, and it is still going strong according to my old neighbours.

Electrics I would place exposed.
 

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