should have an R-value of about R-38 Energystar.gov basics salesperson Energy Star Tips on adding attic insulation from Energy Star EPA’s Energy Star® DIY guide adding attic insulation properly insulated ENERGY STAR insulation Energy Star attic insulation recommendation Tips on adding attic insulation from Energy Star gives it an R-value of around R-38 Department of Energy's guidelines﻿ More information ENERGY STAR Insulation Level basics Energy Star: Isolamento térmico no sótão [em inglês] Energy Star DIY ADDING ATTIC INSULATION insulation levels Energy Star DIY ADDING ATTIC INSULATION about 10 to 14 inches of insulation 10 to 14 inches Energy Star Attic insulation Attic Insulation insulation attic insulation tips Energy Star recommends R-38 Energy Star recommends R-38