CertainTeed MemBrain™...The Smart Vapour Barrier for walls.
MemBrain™ Smart Vapour Retarder is a polyamide film that changes its permeability with the ambient humidity condition. The product's permanence is 1 perm or less when tested in accordance with ASTM E96, dry cup method, and increase to greater than 10 perms using the wet cup method. MemBrain™ allows closed building envelope systems to increase their drying potential with seasonal climate changes. With a high resistance to water vapour in winter or low humidity, MemBrain™ behaves like a moisture vapour barrier such as 6-mil polyethylene sheeting. With an increase in relative humidity, MemBrain™'s permeability increases dramatically, permitting drying to occur and decreasing moisture accumulation within the construction and the potential moisture damage.
This product can be used in place of traditional vapour retarders with unfaced fibreglass insulation, loose fill, or spray foam to provide an insulation system that is ideal in some of the more severe climate condition areas in terms of both temperature and humidity.
MemBrain™'s performance in rooms with short peaks of high humidity, such as bathrooms and kitchens, will not be affected because of the buffering action of interior finishes.
Do not use low permanence interior finishes such as vinyl wallpaper or vapour retarding paints with MemBrain™. The drying benefits of MemBrain™ will diminish with the use of low permanence finishes.