This specification covers prefabricated bituminous sheet materials reinforced with a combination of polyester fabric and glass fiber, with or without granules, modified by styrene butadiene styrene (SBS) thermoplastic elastomer, and are intended for use in the fabrication of multiple ply roofing and waterproofing membranes. This specification is intended as a material specification only. Hence, issues regarding the suitability of the specific roof constructions or application techniques are beyond this scope. Also not addressed here are in-place roof system design criteria such as fire resistance, field strength, impact/puncture resistance, material compatibility, uplift resistance, and others. Materials shall conform to specified values of the following dimensional and physical properties: total and bottom coating thickness; net mass per unit area; peak load before and after heat conditioning; elongation at peak load; ultimate elongation; tear strength; low temperature flexibility; dimensional stability; compound stability; and granule embedment.