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After air sealing with spray foam, contractors blew in 13 inches of cellulose insulation, which should go a long way towards making my house more energy efficient and lowering my electric bills.
Q. I'm going to be removing the existing fiberglass batts from the attic of a moderately leaky older home, doing some air-sealing, and re-insulating with 16 inches of loose-fill cellulose. According to the homeowner, a dusting of fine powdery snow sometimes covers the batts after snowstorms, apparently because it sifts through the ridge cap of the metal roof. This hasn't seemed to hurt the batts any, but because cellulose is organic, I'm wondering if these occasional dustings of snow could lead to rot or mold.
A. Bill Hustrunk, technical manager of cellulose manufacturer National Fiber, in Belchertown, Mass., responds: The amount of snow you describe won't do any harm. Cellulose is highly hygroscopic, meaning it can disperse moisture over a very large internal surface area and then dry back out to reestablish its moisture equilibrium. Because of this,...
