This specification covers SEBS (styrene-ethylenebutylene-styrene)-modified mopping asphalt intended for use in built-up roof construction, construction of some modified bitumen systems, construction of bituminous vapor retarder systems, and for adhering insulation boards used in various types of roofing systems. This specification is intended as a material specification and issues regarding the suitability of specific roof constructions or application techniques are beyond its scope. The specified tests and property values are intended to establish minimum properties. In place system design criteria or performance attributes are factors beyond the scope of this specification. The base asphalt shall be prepared from crude petroleum and the SEBS-modified asphalt shall incorporate sufficient SEBS as the primary polymeric modifier. The SEBS modified asphalt shall be homogeneous and free of water and shall conform to the prescribed physical properties including (1) softening point before and after heat exposure, (2) softening point change, (3) flash point, (4) penetration before and after heat exposure, (5) penetration change, (6) solubility in trichloroethylene, (7) tensile elongation, (8) elastic recovery, and (9) low temperature flexibility. The sampling and test methods to determine compliance with the specified physical properties, as well as the evaluation for stability during heat exposure are detailed.