This specification covers asphalt-impregnated and coated glass felt roll roofing surfaced on the weather side with mineral granules, for use as a cap sheet in the construction of built-up roofs. The glass felt shall be a thin porous sheet composed predominately of fine glass fibers uniformly deposited in a nonwoven pattern. It shall contain a water-insoluble agent and may be reinforced with random, or parallel oriented glass yarns, or both, which may be gathered or twisted, bonded or unbonded. The products shall meet physical property requirements as to pliability, mass loss and behavior on heating, moisture, and dimensions (width, mass, and area).