Vapour Barrier For Warm Flat Roof

If it is not a habitable space or as per the old design for flat cold roofs then you would use foil backed plasterboard which acts as a vb.

Vapour barrier for warm flat roof.

Much like the cold roof it stops the transfer of warm moist air from inside the building into the warm roof layers. The vcl is easier to maintain in a warm roof construction as it s generally out the way of the dangers of plasterboard fixings and downlighters. A vapour control layer helps you shield your building from the consequences of condensation. A vapour barrier sometimes referred to as vapour retarder is typically a plastic or foil sheet used for damp proofing to prevent interstitial condensation from forming in various building assemblies such as walls roofs foundations and floors.

Condensation is generated when warm moist air rises and condenses into a liquid on contact with the cooler areas above the insulation. Ideally you need to ventilate the roof and have a 50mm air gap above your insulation. Often the vcl in a warm roof is bonded to a timber substrate which helps the integrity however in a warm roof the vcl has two important functions. Rose 1997 regales readers of this history.

A roof design that includes an adhered roof membrane with multiple layers of insulation with board joints offset and staggered over a vapor retarder air barrier helps lower the risk that air and the moisture it carries will infiltrate the roof system. Vapour control layers at roofing superstore our choice of flat roof materials includes everything you need to create a long lasting weather proof flat roof that performs and looks good too. The buildup of a warm flat roof starts with a good vapour barrier followed by insulation then more decking or just the roofing materials depends on if you want the roof soft or solid. The notion behind a vapour control layer is to install it on the room side of the insulation so it stops the passage of warm moist air entering the structure.

Including fibreglass roof kits torch on felt and liquid rubber products everything you need for flat roofing is in one place. It is frightening indeed that construction practices can be so dramatically. Vapor barriers are also a cold climate artifact that have diffused into other climates more from ignorance than need.