Ok. Bit dull but…

Having just moved house I have a garage in a block – it’s on the end of the block, single skin walls and cement/asbestos corrugated roof. It appears to develop a bit of condensation in there and I don’t really want all that moisture around my bikes.

I want to use it as a storage/workshop kind of space but there’s no power to it. I’m in the process of rigging up some solar charged 12v lighting in there but I’m wondering about cheap forms of insulation to try and prevent the damp air.

Anyone solved a similar problem? Googling the issue throws up many different suggestions…

Advice appreciated.

Had a similar problem with a metal-roofed garage. I bought a job lot of 50mm thick polystyrene sheets and glued them to the ceiling.

Our garage had a condensation issue – it was largely coming up through the concrete floor as there is no membrane. I put a few coats of floor paint on which greatly reduced it.

I would have preferred to put a non-slip self levelling screed (epoxy or polyurethane) but wanted a quick fix and never got round to it.

Putting a cheap hard wearing carpet down with a plastic backed underlay also works and is nice and warm to work on.

Your roof is probably concrete fibre stuff and not asbestos.

it’s on the end of the block, single skin walls and cement/asbestos corrugated roof. It appears to develop a bit of condensation in there and I don’t really want all that moisture around my bikes.

that should be as secure as a chocolate teapot, as for insulation, get sme insulation from wickes or b and q, cut to length,and then fix to inside of roof with chicken wire, just done it for a customer and it seriously improves the warmth.

it’s on the end of the block, single skin walls and cement/asbestos corrugated roof. It appears to develop a bit of condensation in there and I don’t really want all that moisture around my bikes.

that should be as secure as a chocolate teapot, as for insulation, get sme insulation from wickes or b and q, cut to length,and then fix to inside of roof with chicken wire, just done it for a customer and it seriously improves the warmth.

It’s only condensation?

I used 50mm thick kingspan sheets and expanding foam to seal any gaps, seems to have worked a treat:-)

Found mould on saddles and bar tape so would rather get it fixed. There is a DPC on the floor so it probably isn’t coming up – I like the carpet idea still. Nice ideas for cheap insulation – was worried I was looking at some sort of expensive closed cell spray foam arrangement! Now I’m thinking kingspan and glue.

This will cover the air gap. Should I fit an airbrick or is it best to not bother with airflow, it’s not a heated space.

Any one used epoxy paint/sealant as a moisture repelent – I understand these cement roof tiles are pourus.

As for security. It’s the best I have so will have to do. Going to fit a garage defender ASAP, and we’re in a pretty friendly/neighbourhood watchy low crime cul-de-sac kind of area – and the other garages in the block look more inviting that ours to thieves (dark corners and lax security) – unless they spy what I’ve got in there of course!

The thing is supper dooper security and they know theres something worth while in there, decent locks and an alarm should hopefully work as oppose to a door restrictor, that only works on the bottom of the door, theyll bend the door out at the top.

You could also make a false floor from 3 x 2 studding treated timber, fill the void with insulation, and cover with chipboard etc.

Rigid insulation board and a bit of squirty foam is probably the cheapest option, but will look a bit rubbish and will be time consuming to fit…especially to what is potentially an asbestos cement roof that you would want to avoid drilling into.

For a ‘done in a short afternoon’ job, you want expanding foam insulation. Its not the messy, highly flammable and extremely expensive canned stuff, it comes in two canisters with a spray gun and is extremely easy to apply as long as you warm the cylinders properly and change the nozzles regularly. I used it in my camper conversion. Foam to cover 16m square at 1″ thickness will set you back around £285. You will find the condenstation will move to the next coldest surface, probably the metal door.

Is the condensation bad first thing in the mornings?

Sounds like its night sky radiation / cooling. Warm(ish) days cold clear nights. Particularly problematic with single skin metal roof decks. Insulate or ventilate are solutions.

I would suggest looking to add ventilation first to see if it provides a solution. A bit suck it and see. Aim to try and promote cross flow ventilation.

Ideally any insulation should be in contact with the internal face of the roof sheet to eliminate air voids. Otherwise these should be venilated.

Is it a new or an old development? If old the roof sheets will be asbestos cement so tread carefully!

I think it’s fairly well vented already – but you’re probably correct with the night sky radiation.

Agree with the insulation being in contact with the surface which is why I’ve been reluctant to fit Kingspan so far. Spray foam might be the next step then. It’s not cheap though.

All depends on what you want to spend???

As mentioned Kingspan or similar, foamed to the ceiling/roof. hold it in place with a length of timber till the foams set. No screwing, drilling into existing ceiling/roof. Carpet on the floor and walls??

Cheapest would prob be the standard loft insulation held in place with chix wire (as said)

An air brick might help air flow

Loft insulation could become sodden, and will probably fall down. If it gets too wet, could bring the roof down?!

I agree the spray foam appears expensive, but when you add up the rigid insulation, plus a load of canned foam, you’ll probably find its not far off. The major benefit of the spray foam is it will block all draughts, minor leaks, and will help hold the roof together. As the foam will stick to the corrugated roof it will eliminate condensation, whereas rigid board may still get wet in the voids above it, which will then leak through.

Might also be water coming through the walls, in normal construction the cavity stops water penetrating from the outside. WHen I moved into my brand new house 10 years ago the detached single skin garage had water pissing through the walls (very porous bricks in my case although all bricks and stone are to some extent porous). There was a membrane under the concrete slab and a damproof course. I fixed it by putting extra damproof membrane into the walls and then covered the entire wall surface with the plastic sheet they used under the slab. Held it on the walls with 50mm baton and then filled the cavity with loft insulation and then chipboard over the top. Pretty much stopped the damp problems. Also filled the voids between rafters with polysturene sheet and the same for the rear of the door. Only condensation issues now are when i have the gas heater running.

same problem here
just purchased 17 rolls of 170mm loft insulation from home base for £22
WORTH A TRY ?
chicken wire and a bag of staples to hold it up. im worried it just gets soaked do going to to a test area first.

Where is the heat coming from to form condensation? i.e. surely for condensation to form there must be a significant heat difference between outside and inside.

I have a garage in a block of 3 with a corrguated fibrous cement roof, single skin walls, old workshop style roller door that slides to the side rather than an up and over and never had any condenstaion issues. There’s electricity in it, but nothing putting out any heat so it is roughly the same temp as outside.

Ventilation can help. I had a concrete garage with no insulation at all. I never had condensation issues as there was good air flow. Insulation won’t remove dampness from the air.

same problem, I looked and large sheets of corrugated plastic work out about the same price as chicken wire in B&Q, so was thinking about loft insulation and that. If I remember correctly, about 70 quid all in for my garage.

I got rid of the the condensation in my garage by fitting a humidity controlled fan (try the icon from TLC Direct) and cladding the outside with overlapping 6″ boards on batten. Not cheap, but looks a helluva lot better!

just purchased 17 rolls of 170mm loft insulation from home base for £22
WORTH A TRY ?
chicken wire and a bag of staples to hold it up. im worried it just gets soaked do going to to a test area first

Fibreglass or recycled plastic bottle insulation is usually made from plastic or glass so iit doesnt absorb water, try some in a bucjket of water and see.
Also the roof may be permeable, eg leaks coat with bituminous paint, DONT STAND ON ROOF TO DO IT T HOUGH.