TEMP-COAT 101 can be used on the exterior or interior. As a thermal reflective coating, a 15 mil thickness has been rated by certified labs equivalent to an R-20. TEMP-COAT 101 is applied using airless spray equipment. Coverage at 15 mils is 60sq. ft. per gallon. TEMP-COAT 101 is a perfect fit for metal, shingle, BUR and other roof surface types for use on exterior roof and wall surfaces. In some cases, a primer is recommended. This product offers a wonderful opportunity to add R value back to a structure that is poorly insulated or a building in which the insulation has failed. This product is applied and the old insulation is left in place.