Vapor Membrane Roof

The billowing roof membrane can also create a sound issue for the owner as it flaps up and down.

Vapor membrane roof.

The bottom membrane s primary function is that of an air barrier but it s material characteristics are such that historically it has also been a vapor barrier. The roof is a large part of the building envelope and therefore has a significant impact on the flow of energy in and out of buildings. The purpose of a vapor retarder is to minimize or reduce water vapor diffusion into a low slope roof or wall system. A separate air barrier would need to be installed below the membrane likely below the insulation layer as well.

The firestone v gard vapor control membrane is designed to be used as vapor control layer in firestone roofing systems. When discussing air barriers roofing membranes and the building envelope another important topic comes to mind. Typically a vapor retarder has to have a perm rating of 1 0 or less to be successful. In fact it is almost a perfect vapor barrier.

Because of the billowing effect a mechanically attached roof membrane does not count as an air barrier. There is often confusion between air barriers and vapors retarders. 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. Everyone knows that water in roof systems is never a positive.

That reduction of air and moisture infiltration can then help improve roof longevity. Vapor control membranes play a very important role in this.