CertainTeed’s MemBrain™ Continuous Air Barrier & Smart Vapor Retarder remains tight in the winter when humidity is low to prevent moisture from entering the wall cavity, while increasing permeability in the summer to let moisture escape. Unlike traditional polyethylene vapor retarders that may actually trap moisture, MemBrain helps keep walls dry all year-round, significantly lowering the health and structural risks associated with moisture and mold. www.certainteed.com