This attic had existing loose fiberglass insulation with an R-value of 3.2 per inch. This material allows air to easily pass through it and escape into the unconditioned attic and out of the home. For this homeowner, we installed an R-38 of blown-in cellulose insulation. Cellulose is more dense than the loose fiberglass, is 85% recycle material, and is fire retardant due to being manufactured with borate, a substance that deters pests.