Vapour Control Layer For Warm Flat Roof

A vapour control layer or vcl on a warm flat roof sits between the roof decking and the insulation.

Vapour control layer for warm flat roof.

This could be a 1000 gauge min polythene sheet. Because of this the vcl always sits at the warm side of the insulation. Including fibreglass roof kits torch on felt and liquid rubber products everything you need for flat roofing is in one place. Be it a cold or warm roof construction the primary function of a vcl is to keep warm moist air from inside the building inside the building.

A vcl is always used as close to the inner face of a wall as possible and reduces the amount of moisture passing through the layer to low levels ensuring only insignificant amounts of condensation occur within the structure. 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. With any warm flat roof detail such as this a vapour control layer should have been laid on top of the roof deck underneath the insulation. If this has not been done then we would recommend that you install one underneath the joists before the plasterboard goes up.

The answer to keeping timber framed walls and roofs dry is to use a layer to restrict the flow of moisture but not to try and stop it. Vapour control layers should be provided to warm roofs and. A vapour control layer helps you shield your building from the consequences of condensation. Include at least one layer of bitumen roofing membrane s2p3 below the insulation fully bonded or mechanically fixed to the structural deck as appropriate or a suitable self adhesive or torch on membrane.

This is known as a vapour control layer vcl or a vapour retarder. It has transpired that there is no vapour control layer fitted. It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation. 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.

Using a vapour control layer to control condensation. A vapour control layer is designed to catch this vapour preventing it from condensing on the insulation or elsewhere in the loft space or attic. Condensation is generated when warm moist air rises and condenses into a liquid on contact with the cooler areas above the insulation.