MemBrain™: Just how smart is it?

No matter where you live, no matter what your climate, moisture can put both your family and your home at risk. In hot humid summers, it migrates into your walls from the outside. During cold dry winters, the moisture generated by everyday indoor activities – cooking, laundry, bathing, etc. – creeps into the walls from the inside. Once it’s in there, it can condense on every surface, compromising your insulation and creating a breeding ground for mold and a catalyst for rot.

Conventional vapor barriers (or more accurately, vapor retarders) like polyethylene sheeting and the kraft facing on fiberglass insulation aren’t a complete solution. In fact, they can trap moisture inside your wall cavities, increasing the risk of future problems.

MemBrain™ by CertainTeed may look like a normal poly film, but it’s far from it. It’s a polyamide (nylon)-based material with pores that adapt in size based on ambient humidity levels. That’s important, because when the summer humidity inside your walls is high, MemBrain opens up to let the walls breathe and the moisture inside them dry out. In winter’s low humidity, MemBrain acts like a conventional vapor retarder, blocking moisture from getting into the walls. That means all year long, MemBrain dramatically reduces the risk of damaging moisture accumulating within the wall cavity.

The manufacturer calls this remarkable ability MoistureSense™ Technology and the product a smart vapor retarder.

If you wonder, even for a minute, whether enough moisture can get into your wall to cause real problems, just Google “mold on insulation” and look at the images that come up. I dare you.


So is MemBrain a better solution than a conventional vapor retarder? That seems pretty clear too. It has won a Most Valuable Product (MVP) award from Building Products Magazine, an Innovative Housing Technology Award in the energy category from the National Association of Homebuilers Research Center and EH Publishing (the publishers of TecHome Builder), and the trust of professional builders and contractors all across North America.