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, there are no localized wet areas that might give mold or other microorganisms the moisture they need to multiply. The borate-based fire retardants used in cellulose help, too, because they have antimicrobial properties.
The attic you'll be working in sounds well-ventilated, but cellulose's ability to accommodate moisture also allows it to work in unvented dense-packed roof assemblies. Its density prevents airflow - which we now know is the major transport mechanism for moisture - while moisture that enters through diffusion transport is managed by its...
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