This specification covers the standards for asphalt impregnated and coated glass fiber base sheet intended for use as the first ply of built-up roofings. This sheets are also suitable for use as a vapor retarded under roof insulation or between multiple layers of roof insulation. The materials shall conform to the physical requirements, dimensions, and masses prescribed herein. The products shall not crack nor be too sticky as to cause damage upon being unrolled. The specimen shall also undergo testing to determine the following properties: breaking strength, moisture content, and pliability.

1.1 This specification covers asphalt impregnated and coated glass fiber base sheet, with or without perforations, for use as the first ply of the built-up roofing. When not perforated, this sheet is suitable for use as a vapor retarder, with a solid mopping of asphaltic material, under roof insulation or between multiple layers of roof insulation.

1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.