Perm-A-Barrier VPO is blackish green and designed for exposure to indirect and intermittent sunlight, such as behind open joint rain screen systems. Perm-A-Barrier VPO is a one component, fluid-applied vapor permeable air barrier membrane that provides continuous air tightness and water protection throughout the wall assembly.

Perm-A-Barrier VPO is for wall assemblies requiring "breathable" characteristics. As a vapor permeable membrane, Perm-A-Barrier VPO permits the transfusion of water vapor that may otherwise condense in the wall structure; but is impermeable to liquid water, which allows the material to act as a water drainage plain.