MemBrain

[kurt]

Anyone seen any of this Certainteed Membrain SMART vapor retarder? It's supposedly some kind of "goretex" sheet, that adjusts from low permeability in low humidity to high perm in high humidity.

Sounds very interesting; just wondering what anyone else knows...

[Steve Knight]

Kurt,

Some of the builders in my area are using this product for the vapor retarder in finished basements. The product is suppose to provide a vapor barrier with a vapor permeance of 1 perm or less during winter, but allow below grade block or concrete wall to dry to the inside during summer months and prevent moisture buildup inside a fiberglass energy wall.

I believe the University of Minnesota did some tests on this product, but I have not seen the results.

[Jim Katen]

Originally posted by kurt

Anyone seen any of this Certainteed Membrain SMART vapor retarder? It's supposedly some kind of "goretex" sheet, that adjusts from low permeability in low humidity to high perm in high humidity.

Sounds very interesting; just wondering what anyone else knows...

Doesn't felt behave like that?

- Jim Katen, Oregon

[kurt]

Well, in my perfect world, there would be no Tyvek, housewrap, polyethylene sheet, or whatever; everything would be lapped w/ 15# felt.

I use it for just about everything related to vapor transmission control. All the old joints I work on that had felt underlayment in walls, under floors, or wherever, are always in perfect condition; no mold, no stain, no nothing but perfect conditions.