This specification covers asphalt-saturated organic felt used in roofing and waterproofing. Two types of asphalt-saturated felts are presented: type I - commonly called No. 15 asphalt felt, and type II - commonly called No. 30 asphalt felt. In the process of manufacture a single thickness of dry felt shall be saturated with an asphaltic saturant. The methods for the determination of openness of the perforations in saturated felts are presented in detail.