CertainTeed's Flintlastic® Base 20 is a robust SBS-modified bitumen base sheet, delivering the benefits of a homogenous roof system when paired with SBS-modified bitumen cap sheets such as Flintlastic® GMS, Flintlastic® FR-P and Flintlastic® Premium FR-P. Many members of the design and specification community prefer multi-layer modified bitumen roof systems constructed with the same polymer-modified material and application methodology for base and/or interply and cap sheets, to optimize stress resistance to the roof system with materials expanding and contracting at the same rate. This 92 mil base sheet is manufactured with tough, dimensionally stable fiberglass reinforcement that is highly resistant to tearing and punctures. The fiberglass mat is saturated and coated with an SBS-modified asphalt with elastic, waterproofing properties. Flintlastic® Base 20 can be mechanically attached but is more commonly mopped with hot asphalt or cold adhesive, such as FlintBond® Brush to...See More avoid roof penetrations and allow for extended warranty durations. Reach out to your local CertainTeed Territory Manager to request a sample and demonstration of Flintlastic® Base 20. See Less