Roof Vapor Retarder

Sopra vi is composed of a proprietary formulation of bitumen and is reinforced with a high quality random glass fiber mat.

Roof vapor retarder. In a low slope roof assembly the vapor retarder is normally installed under the primary roof insulation. Typically a vapor retarder has to have a perm rating of 1 0 or less to be successful. 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.

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. Sopra vi is a bitumen coated base sheet for use in approved built up roof assemblies. This eliminates the need for a separate air barrier that could potentially prevent the moisture from escaping. The need for use and design of a vapor retarder in the design of a roof system used to be a hotly debated topic.

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. 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.