Warm Flat Roof Construction Vapour Barrier

There is no requirement for any air gaps.

Warm flat roof construction vapour barrier.

It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation. A vapour control layer or vcl on a warm flat roof sits between the roof decking and the insulation. It has transpired that there is no vapour control layer fitted. Vapour control layers vcl.

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. 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. Because of this the vcl always sits at the warm side of the insulation. The roof is an unventilated warm roof design finished with a single ply membrane.

Provided your vapour control layer is intact then there should not be any risk of condensation. Including fibreglass roof kits torch on felt and liquid rubber products everything you need for flat roofing is in one place. Ideally you need to ventilate the roof and have a 50mm air gap above your insulation. 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.

If this is a habitable room beneath the roof then you should be constructing a warm roof as per building regulations c l. For all warm flat roofs a fully intact vapour barrier would be required on the room side under the insulation. 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. The architect plans stated requirement for a vapour control layer below the insulation or a 3 in 1 insulation board including vapour control layer and an additional foil backed plasterboard.

A vapour control layer helps you shield your building from the consequences of condensation.