USP Base Sheet is manufactured with a heavyweight, select fiberglass mat designed and constructed to be strong, while remaining wrinkle resistant. The strong glass mat is saturated with a high quality, nonfilled asphaltic bitumen for a strong, durable yet uniformly consistent in roll out for ease of application. USP Base Sheet is designed for use as a replacement for coated organic base felts, as the fiber glass (inorganic) mat reinforcement is rot resistant and has low moisture absorption. It is ideal for applications as a base ply in where mechanical attachment of the sheet to the roof substrate or roof deck is desirable, or for hot mop specifications, compatible cold adhesive applied in conjunction with cold adhesive specifications and torch applied roofing applications and specifications requiring base sheet.