Built up roofing systems
B.U.R. These roof systems are commonly referred to as “tar and gravel” roofs. BUR systems generally are composed of alternating layers of bitumen and reinforcing fabrics that create a finished membrane. Built up roofs generally are considered to be fully adhered if applied directly to roof decks or insulation. The bitumen typically used in BUR roof systems is asphalt, coal tar or cold-applied adhesive. Surfacing for built up roof systems include aggregate [such as gravel, slag or mineral granules), glass-fiber or mineral surfaced cap sheets, hot asphalt mopped over the entire surface, aluminum coatings or elastomeric coatings. The properties in the cap sheet is the determining factor the CRRC uses to measure the cooling ability of the roof.