Vapour Barrier For Cold Flat Roof

Because of this the vcl always sits at the warm side of the.

Vapour barrier for cold flat roof.

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. In general the installation of a cold roof is not recommended for the construction of new properties. Most diagrams on the internet i have seen have plasterboard on joist insulation air gap osb board then roofing material.

I am building a cold flat roof on an extension. 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. Any advice would be great. A flat roof vapour barrier such as iko s mvp modified vapour protector offers appropriate moisture protection.

Bituminous vapour retarders asphalt mixed with felt or fiberglass or non bituminous vapour retarders plastic. 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. For cold flat roofs the vapour layer needs to be positioned underneath the insulation layer on top of the room below to create an effective barrier. Self healing if punctured by fixings.

The sloping ceiling areas include closed cell or foil backed rigid board insulants most of which are highly vapour resistant. When the temperature of the vapour falls to or below its dew point the water vapour condenses on cold surfaces. It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation. Its not cheap purchasing it by the role and by the pallet load is cheaper but is a considerable layout.

Flat roof vapour barrier materials when constructing a flat roof there are two types of materials commonly used. Vapour resistance of 2000 mns g. Room in the roof constructions often use a combination of warm and cold roof constructions with varying types of insulation. Temporarily waterproofs the roof can stay uncovered for up to 3 months.

Why is it the best vapour barrier for flat roofs. Condensation within a flat roof mainly occurs during cold weather when moisture vapour in the air which has been generated within the heated building rises from the room below into the cold roof void above the ceiling.