Roof Vapor Retarder

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.

Roof vapor retarder.

A vapor retarder is commonly installed on the warm interior side of a roof or wall. 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. Sopra vi is a bitumen coated base sheet for use in approved built up roof assemblies. Typically a vapor retarder has to have a perm rating of 1 0 or less to be successful.

The need for use and design of a vapor retarder in the design of a roof system used to be a hotly debated topic. In a low slope roof assembly the vapor retarder is normally installed under the primary roof insulation. It appears now when vapor retarders are needed more than ever the design community seems to have lost interest which is not good considering how codes and standards altered through concerns for energy savings have changed how buildings are designed constructed and operated. Gaf sa vapor retarder is composed of a proprietary formulation of elastomeric styrene butadiene styrene sbs polymer modified bitumen in combination with a high tack self adhesive.

Sopra vi is composed of a proprietary formulation of bitumen and is reinforced with a high quality random glass fiber mat. Gaf sa vapor retarder is an sbs modified bitumen vapor retarder for use in approved gaf roof assemblies.