Cold Flat Roof Vapour Barrier

Flat roof vapour barrier materials when constructing a flat roof there are two types of materials commonly used.

Cold flat roof vapour barrier.

Room in the roof constructions often use a combination of warm and cold roof constructions with varying types of insulation. A flat roof vapour barrier such as iko s mvp modified vapour protector offers appropriate moisture protection. The sloping ceiling areas include closed cell or foil backed rigid board insulants most of which are highly vapour resistant. Applicability limited to very cold subarctic and arctic regions.

The notion behind a vapour control layer is to install it on the room. This wall is a further variation of figure 6 but now it has a class i vapor retarder on the interior a vapor barrier completely eliminating any inward drying potential. Flat concrete roofs are generally not ventilated since the ceiling internally is generally a plaster and skim coat directly to the underside of the cold concrete. When the temperature of the vapour falls to or below its dew point the water vapour condenses on cold surfaces.

Any advice would be great. Creating a void between the old ceiling and new is better but ideally you need to eventually consider insulating the top of the concrete roof with solid insulation and a better. A vapour control layer or vcl on a warm flat roof sits between the roof decking and the insulation. 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.

Most diagrams on the internet i have seen have plasterboard on joist insulation air gap osb board then roofing material. Whether you re repairing a flat roof or laying a new one from scratch you ll find all the materials you need here. I am building a cold flat roof on an extension. Including flat roof vapour barrier for extra secure roofing solutions.

Bituminous vapour retarders asphalt mixed with felt or fiberglass or non bituminous vapour retarders plastic. Do i need a vapour barrier between the plasterboard and the bottom of the joist. Cold roof areas usually include vapour open fibrous insulation e g mineral wool quilt.