Patent ID: 7914634

Claim:
A method for providing a vapor retarder for a building, the method comprising: providing a film having a vapor diffusion resistance that varies as a function of the relative humidity of ambient air, wherein the film includes a mixture consisting of a polymer and an ionomer, wherein the ionomer comprises 50% to 80% by weight of the mixture, wherein the ionomer is a copolymer including: 50 mol-% to 99 mol-% ethylene; and 1 mol-% to 50 mol-% methacrylic acid; and having acid groups that are 0.5% to 100% neutralized with inorganic cations and wherein the polymer consists of a polyester, a polyurethane, or a polyolefin, or a combination thereof; and applying the film to a building so as to provide a building vapor retarder.