Humidity No Problem for MemBrain

Meghan Stromberg, Senior Editor
August 1, 2003
Professional Builder

The benefits of a vapor barrier are indisputable — it retards moisture penetration into insulated cavities, thus reducing the chances of moisture buildup, rot and mold growth. As the weather changes from cold and dry in the winter to hot and humid in the summer, that same vapor barrier becomes a potential liability, as it limits the drying capabilities of cavities.

MemBrain is CertainTeed's new solution to the problem. Made of a nylon-based material, MemBrain alters its permeability according to the ambient humidity. The pores change size, allowing a permeability of less than 1 perm at low humidity to greater than 20 perms at high relative humidity.

The product replaces traditional polyethylene vapor retarders with unfaced fiberglass insulation. "MemBrain allows closed building envelope systems to increase their drying potential with seasonal climactic changes," says Glenn Singer, manager of building science for CertainTeed's Insulation Group. "It can help reduce the risk and liability concerns due to excess moisture in homes that is so common today."

The "smart vapor retarder" concept debuted in Europe seven years ago and is now available in the United States.

MemBrain, a patented "smart" vapor barrier, changes its permeability so moisture can escape wall cavities.