Fiberglass-reinforced construction lays flat for an attractive roof appearance and avoids telegraphing wrinkles through your shingles, Each 36-Inch x 144-Feet roll of Shingle-Mate Underlayment covers approximately 432 sq. ft., excluding laps, Each roll equates to 2 rolls typical #30 asphalt felts, resulting in less rolls to load and install on the roof, Helps eliminates the need to slit wrinkled felt (which can compromise the integrity of your roofing system), For use with asphalt shingles and can be used over plywood, wood planks and other approved decks for versatility, NOTE: Shingle-Mate® Roof Deck Protection must NOT be left exposed to precipitation,