Raw materials and production methods for coal-tar flat-roof pitch and specifications for fiat-roof bituminous materials are discussed. The importance of satisfactory long-term service as a basis for specifications of basic types is emphasized. Properties of bitumens determined by long-term basic fundamental studies which govern the success or failure of roofing binders are described. Particular reference is made to the chemical, water absorption, rheological, and adhesion properties; the resistance to light, water, and oxidation; and the results of accelerated and atmospheric exposure. Investigations of the properties of currently available bituminous materials for flat-roof construction are described and data presented. The authors recommend coal-tar pitch for dead level and low slope roofs and non-Newtonian asphalts for higher slope built-up roofing structures.