# Vapour barrier for unheated garage



## travertine

Hi. Our new garage is being built with a wooden frame and I wanted to install a vapour barrier. The garage won't be heated so moisture in and outside will be present.

We're going to use a metal roof so I thought a waterproof membrane under the roof would deal with any condensation and direct it down and out. Under the waterproof membrane will be insulation - probably polystyrene or polyurethane boards (for ease of fixing).

The walls of the garage will be constructed with wooden studs. The sequence for the materials from inside to outside I'm guessing will be OSB, insulation, OSB, vapour barrier, batons (for air circulation), then cladding.

In Canada they use a heavy coated sheet (a bit like tar paper) called Tyvek that is attached to the external OSB and presumably could be used under the metal roof. Does anyone have any experience here in France with products that will do the job? If so could you share your wisdom. Thanks.


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## Lalla

I've seen metal roofing sheets that have a layer bonded to them that stops condensation forming.

Here's the sort of thing I mean:









Anti Condensation Roofing Sheets


Our anti-condensation roofing sheets are designed to eliminate any concerns about condensation with your roofing. The anti-condensation backing works by absorbing any formed droplets and will retain…




www.roofingsheetsbyrhino.com


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## travertine

Thanks for that suggestion. My British builder mentioned such a product a while ago but I've not seen it in the usual hardware stores e.g. Bricomarche, Weldom etc. Maybe he was also thinking about the UK. Will see what I can find.


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## Lalla

travertine said:


> Thanks for that suggestion. My British builder mentioned such a product a while ago but I've not seen it in the usual hardware stores e.g. Bricomarche, Weldom etc. Maybe he was also thinking about the UK. Will see what I can find.


You wouldn't see those steel roofing sheets in a typical DIY store in the UK, it's more from a specialist supplier.


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## LFBEUSTON

Every time you open the garage door water vapour will come in. Condensation only occurs when the vapour is subjected to a change in temperature. If you keep the garage in its 'natural' state and allow the temperature to fluctuate normally i.e. when it is cold don't heat it and vice versa then there isn't any need for 'special' roofing. If anything the best way to stop condensation is leave the garage door open so there is a free flow of air!!


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## ccm47

If you have the slightest intention of doing any jobs in the garage make sure you put in some sound insulation. Rain pouring onto the roof is deafening. We once sheltered from a cloud burst in a metal roofed horse shelter, not a good experience.


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## LFBEUSTON

ccm47 said:


> If you have the slightest intention of doing any jobs in the garage make sure you put in some sound insulation. Rain pouring onto the roof is deafening. We once sheltered from a cloud burst in a metal roofed horse shelter, not a good experience.


Is it really worth the expense, Why not wait until it stops raining,have a cup of coffee!!!!


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