Roof Vapor Retarder

Typically a vapor retarder has to have a perm rating of 1 0 or less to be successful.

Roof vapor retarder.

Gaf sa vapor retarder is an sbs modified bitumen vapor retarder for use in approved gaf roof assemblies. A vapor retarder is commonly installed on the warm interior side of a roof or wall. Everyone knows that water in roof systems is never a positive. In a low slope roof assembly the vapor retarder is normally installed under the primary roof insulation.

This eliminates the need for a separate air barrier that could potentially prevent the moisture from escaping. Sopra vi is composed of a proprietary formulation of bitumen and is reinforced with a high quality random glass fiber mat. The topside and underside are. When we use a vapor retarder in a roof system it will also act as an air barrier as long as it is sealed at all perimeters and penetrations and is tied to the wall air barrier.

The need for use and design of a vapor retarder in the design of a roof system used to be a hotly debated topic. A vapor retarder is a material or system that is designed as part of the roof system to substantially reduce the movement of water vapor into the roof system where it can condense.