An asphalt-saturated and/or an asphalt-coated felt membrane. Roofing felts are used asunderpayment for shingles, for sheathing paper, and forreinforcements within the construction of built-up roofs.They are made from a combination of shreddedwood fibers, mineral fibers, or glass fibers saturatedwith asphalt or coal-tar pitch. Sheets are usually36 inches wide and available in numerous weights from 10to 50 pounds. These weights refer to excess weight per square(100 feet).