Cold Roof Vapour Control Layer

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.

Cold roof vapour control layer.

Because the waterproofing layer constitutes a vapour control layer on the cold side of the insulation there is a high risk of harmful interstitial and surface condensation on the underside of the deck or the upper surface of the. No vapour control layer is required. Vapour control layers should be provided to warm roofs and. The roof is an unventilated warm roof design finished with a single ply membrane.

It has transpired that there is no vapour control layer fitted. 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. We would recommend either a fully warm roof with insulation on top of the roof deck or a cold roof with a minimum 50mm well ventilated cavity between the roof deck and the top of the insulation. This type of roof has normally been used over small extensions to dwellings using timber joists and plywood deck.

Bs6229 2003 gives advice on vapour control layers in flat roofs and the control of condensation within the building generally. Access hatches to cold roof voids should have. Don t get caught out by ignoring the vapour control layer. Where the ceiling below a cold pitched roof includes a vapour control layer the design should ensure adequate ventilation is provided to the habitable areas to prevent condensation problems in the home.

A vapour control layer helps you shield your building from the consequences of condensation condensation is generated when warm moist air rises and condenses into a liquid on contact with the cooler areas above the insulation. It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation. To solve this we recommend installing an air vapour control layer avcl such as duponttm airguard control beneath the vapour open quilt insulation. A vapour control layer or vcl on a warm flat roof sits between the roof decking and the insulation.

The notion behind a vapour control layer is to install it on the room.