[Closed] Best way to insulate single skin garage?

Is it worth combining these threads?

https://singletrackmag.com/forum/topic/insulate-my-garage-roof-please/

Is it worth combining these threads?

No, its a specific question that I didn't want to get lost in that thread if possible.

Build an interior stud wall in front of the brick wall attached to the floor and rafters (sil gasket between floor and bottom stud). Spaced away from the brick for a complete thermal break. Whatever insulation and vapor barrier that fits your budget (spray foam, mineral wool, wool wool, Kingspan or whatever rigid foam is called in the UK)
French drain/weaping tile perimeter drain outside with whatever other moisture management you need on the footings.

Plasterboard, ply or whatever to finish.

Would be cheaper and easier than outsulation id expect. But depends if you're ok to loose that space internally.

I have a concrete sectional. Can't afford to lose inside same it's small enough already and 3 walls are in my neighbours garden so outsulation not possible.

Just 2 part epoxy closed cell foamed in inside faces. Has worked well .

Might not be the "best" thermally but it's been solid and markedly better than before.

Oh and dont forget ....mostly the worst offender is the door.

Build an interior stud wall in front of the brick wall attached to the floor and rafters (sil gasket between floor and bottom stud). Spaced away from the brick for a complete thermal break. Whatever insulation and vapor barrier that fits your budget (spray foam, mineral wool, wool wool, Kingspan or whatever rigid foam is called in the UK)
French drain/weaping tile perimeter drain outside with whatever other moisture management you need on the footings.

Plasterboard, ply or whatever to finish.

Would be cheaper and easier than outsulation id expect. But depends if you’re ok to loose that space internally.

Cheers

Do I need to ventilate the cavity? The more I read the more I see different responses to this? or would a gap between the wall into the loft space be enough?

I’m practical enough to do it, just want to make sure I do it right.

Can insulated plasterboard just be stuck on to a single brick thickness wall - inside obv! Or would the plasterboard get damp?

An option that may take up less space:

Insulated plasterboard with integral vapour control layer on vertical 50mm deep battens on DPM strips at 600 c/c mechanically fixed to wall.

What are you using the garage for? Unless as an office or something, I just put a fan heater on for 20 minutes if it's uncomfortably cold with a coat on. I do have an insulated roof and a draught proof door, but otherwise it's single skin.

Insulation won't make it any warmer unless you are going to heat it anyway, although it may keep it a little cooler in the summer.

I just put a fan heater on for 20 minutes if it’s uncomfortably cold with a coat on.

Yeah, MTFU and just get a proper winter coat.

Can insulated plasterboard just be stuck on to a single brick thickness wall – inside obv! Or would the plasterboard get damp?

It will get damp, bricks aren't water proof (they're not bad, but not good enough). You'd need a vapour barrier at least - a barrier and air gap even better.

Another option is just closed cell foam (cellotex etc) against the wall, tape it up etc to seal the gaps and you get insulation and vapour barrier in one go. That's how our workshop was built. Plasterboard over the insulation.

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Personally I'm not a fan of putting something directly against a single skin wall. The insulation robs energy flux though the wall anyway reducing drying potential and you cut the ventilation for drying in half. Over time you have the potential for moisture to accumulate in the wall, and migrate to it's base, potentially worsening damp ingress at the floor/wall interface, and degrading the condition of the wall. I would clad the outside and include a ventilation space to keep direct moisture off the exterior, but allow the structure to breath if you went that direction.

Circumstance specific of course.

Personally, I'd do what Ogden says. If you're worried about internal space, you could batten out the wall with DPC behind the battens, and the fix the insulated plasterboard to the battens you'll probably save about 50mm per wall doing it that way compared to a stud (if you build it using 4x2), but it will take longer, especially if the wall is rough.

My office is half of my garage which I insulated.

I build a stud wall, stuck Celotex to it. Screwed battens to the wall and stuck Celotex to them. Stuck Celotex in the floor, then laid some MDF floorboards on top. Celotex ceiling placed on top.

It has been like this for a few years and I'm planning a few upgrades. New double-glazed window is on order and I think I might add ply to the walls and maybe more insulation above (maybe just loft insulation laid on the Celotex?).

I never bothered plasterboarding the walls, I figured it will always be damp (single skin also) and it would end up a mess.

The rest of the garage gets damp but I think this is condensation. I am heating and working in one end and all the vapour must escape. Dehumidifier probably required.

I heat it with an oil filled radiator.

is your garage detached? I take it no heat source?

If it's to combat damp it may be easiest to to improve air flow. Either tile vents or some sort of extractor fan.

is your garage detached? I take it no heat source?

If it’s to combat damp it may be easiest to to improve air flow. Either tile vents or some sort of extractor fan.

Yeah its detached.

The idea is definitely to do stud walls set away from the wall with PIR and tape the joints. I just don't wanna go to the trouble of doing it all and then it all going rotten and need to be torn down. Not sure if I should plasterboard it or use OSB for the walls.

Could air brick into the cavity work?

What are you using the garage for? Unless as an office or something, I just put a fan heater on for 20 minutes if it’s uncomfortably cold with a coat on. I do have an insulated roof and a draught proof door, but otherwise it’s single skin.

Just want to make a nice space to work on my bikes.

If it’s to combat damp it may be easiest to to improve air flow. Either tile vents or some sort of extractor fan.

They all have the downside of making it colder...

A dehumidifier will warm it up a bit whilst keeping it dry - but obviously if you have too much ventilation you're just trying to dehimidify the atmosphere, which isn't going to work.

Yeah OSB, that's what I think I'm going to use. I reckon it will be more resistant to knocks and damp than plasterboard. I don't care what it looks like.

The rest of the garage gets damp but I think this is condensation. I am heating and working in one end and all the vapour must escape. Dehumidifier probably required.

Be better if you just insulated the rest of it surely.

Fwiw ive been heating and working in my concrete sectional for 6 months now since I foamed it. No damp (was condensatingnonnthe roof previously due to the inside heat and cold outside)

Considerable improvement for what was a very quick job. Considering osbing inside to make it look nicer now.

@trail_rat You are probably right but it's massive (long), with a metal door in the "cold end". I don't want to go to the expense of doing it all.

Look at long term running costs of a dehumidifier .

You'll find that initial upfront cost Vs dehumidifying what is essentially the great outdoors might (nee) will be cheaper .

Could easy be a tenner a month

So do I try to ventilate the cavity or not? I’m none the wiser 🤷🏻‍♂️

I’m by no means any expert but if you erect an internal stud wall with vapour barrier I would try add ventilation for the potential build up of moisture. Especially if the floor is a concrete slab. A few air bricks should be fine and easy enough to do. Also make sure you have ventilation in the roof space as well.

I dont think its worth insulating garage fir that use case at all. Assuming you're in there for, say, 2 hours of an evening, the amount of heat lost over those 2 hours won't be massively improved, and however well you insulate it will be stone cold the next time you go in. Just put a fan or ir heater in and turn it on when you want to

Agree with 5lab, the cost of materials and kit to do it could easily run into a few hundred pounds, and then all the heat still disappears out of the metal door.
That much money could power a small heater for a lot of hours if you're only going to be in there a couple of hours at a time.
A colleague of mine has some infra-red heaters set up so they're pointed at him while he's at his workbench, warming him rather than the empty end of the garage.
Maybe some secondhand big thick curtains infront of the metal doors would help with heat loss and some thicker flooring to stand on so that you're not stood on cold concrete.

Interested as I have a similar issue. Our new to us 70s double garage is cold (unsurprising as it's unheated) but it's not really the cold that's the problem, it's the damp that's making all my tools rusty.

I do have to divert the water course that sometimes flows through it (we're at the bottom of the hill and the path through our garden directs the run off under the side door) and fix the flat roof (hoping to lift it a bit and add a pitch) but is there anything else I should be doing? As mentioned above will insulating it actually do anything or should I just paint it inside and throw a heater in there for a bit of comfort for the few winter hours I'll send out there?

G

I've got an internal garage which is double skinned mostly with only a small single skin at the front where it pitches out. There's no heating, the door is uninsulated up and over. It's cold, but the thing that has improved the comfort level is laying carpet tiles on the floor. It stops a lot of the cold coming up through the floor so reduces the feeling somewhat. I have a small electric heater when I'm working in there which serves a purpose. I wouldn't personally bother with trying to insulate it, without heating it's not going to get warmer.

Any tips to insulate the single skin internal wall of a cold integral garage - to stop it acting like a heat sink for the rest of the house? Not too bothered about retaining heat in the garage, it's more for the house benefit.

The wall (garage side) houses every service imaginable - electrical incomer, meter, DB, cables clipped direct, gas and meter, DHW and heating pipes etc. I reckon I can get a good run of battens, notched at the back for the services, but any issues with insulating around or too close to pipes and cables? It feels like it's going to be a massive jigsaw puzzle with some impossible gaps to fill.

May be less hassle (but more £££) to replace the functional but drafty and uninsulated electric roller door?