We installed 6 nominal inches of spray foam insulation on the roof deck of the attic space and 4 inches of open cell foam insulation in the wall cavities. Spray foam insulation creates an air seal, sealing up gaps and cracks that fiberglass insulation and cellulose insulation leave open. This means the home will be more comfortable and energy efficient. The home will have less dust, fewer outside allergens allowed in, reduced outside noise, fewer bugs, and lower energy bills.