I have a garage with a tin roof and I want the insulated, cars winter dries and these drops of water are frozen on the roof of my car, without counting the furnace of summer. Roof made of sheet metal with 3 sleepers.
As you can imagine, the phenomenon results from the condensation that occurs on the underside of the sheets: you release water vapor in the garage (if only by letting the engine of the car turn for a moment) ), and it condenses in contact with the sheet that is cold. The simplest is to fix polystyrene plates of good thickness under them.
Nevertheless the system is not ideal. The best is still to insulate the sheet from the outside by over-roofing, with a system comprising corrugated EPS sheets (polystyrene foam) which marries the cover, then again corrugated sheets of synthetic material. This is the EVERISOL system from ONDULINE.
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