Vapour Barrier For Cold Flat Roof

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.

Vapour barrier for cold flat roof.

Any advice would be great. The notion behind a vapour control layer is to install it on the room. 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. It s the first line of defence against high vapour pressure air entering the roof structure and causing interstitial condensation.

When the temperature of the vapour falls to or below its dew point the water vapour condenses on cold surfaces. Flat roof vapour barrier materials when constructing a flat roof there are two types of materials commonly used. In general the installation of a cold roof is not recommended for the construction of new properties. A flat roof vapour barrier such as iko s mvp modified vapour protector offers appropriate moisture protection.

Its not cheap purchasing it by the role and by the pallet load is cheaper but is a considerable layout. Because of this the vcl always sits at the warm side of the. Room in the roof constructions often use a combination of warm and cold roof constructions with varying types of insulation. Vapour resistance of 2000 mns g.

Why is it the best vapour barrier for flat roofs. 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. Cold roof areas usually include vapour open fibrous insulation e g mineral wool quilt. Bituminous vapour retarders asphalt mixed with felt or fiberglass or non bituminous vapour retarders plastic.

Which ventilation solutions are available. Do i need a vapour barrier between the plasterboard and the bottom of the joist. Temporarily waterproofs the roof can stay uncovered for up to 3 months. Most diagrams on the internet i have seen have plasterboard on joist insulation air gap osb board then roofing material.

The sloping ceiling areas include closed cell or foil backed rigid board insulants most of which are highly vapour resistant. A vapour control layer or vcl on a warm flat roof sits between the roof decking and the insulation.