plastic fibers, mineral wool or fiberglass. Fiberglass is the most common option for attic insulation and may come precut to fit typical attic trusses and rafters. Blanket insulation may also have an air and vapor barrier on one
If there is no vapor barrier, double it to one square foot of NFA for every 150 square feet of attic floor space (half for intake, half for exhaust). These are broad guidelines, so be sure to check with your local building code. (Source: NRCA, Stanley Complete Roofs and Siding, Air...