Vapour Control Layer Cold Flat Roof

Hi i m in the process of building a single story flat roof extension.

Vapour control layer cold flat roof.

Cold flat roofs are difficult to detail correctly but where used they should be in accordance with bs 5250 and have. 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. Warm roof build ups can be installed on most modern construction material types such as concrete timber and timber based sheets. However the cross ventilation does not completely remove the moisture vapour in the ceiling void and a vapour control layer sealed at joints and penetrations is required under the insulation and over the plasterboard to provide a barrier against moisture vapour rising up from the room below.

Vapour control layers vcl. 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. The notion behind a vapour control layer is to install it on the room. Cold bridging through the system is easier to eliminate or control as ordinarily there are no breaches from the structural supports as there is in a cold roof construction.

A vapour control layer or vcl for short is a plastic layer that restricts the movement of warm moist air from inside a property into the fabric of the building. Vcls prevent excess moisture entering a wall s cavity behind the insulation. I have a 3 layer. 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.

Don t get caught out by ignoring the vapour control layer. An effective vapour control layer at ceiling level an unobstructed 50mm ventilation space above the insulation. Vapour control layer for a cold roof. What is the difference between a vapour control layer and a breather membrane.

The type of 3 layer roof. Bs6229 2003 gives advice on vapour control layers in flat roofs and the control of condensation within the building generally. I have been looking through insurance and they seem to ask about type of flat roofs. The flat roof has 2 roof lanterns.

A question for the experts. It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation.