RUBEROID 20 membrane is a tough, resilient modified bitumen membrane manufactured to stringent GAF Materials Corporation specifications. Its core is a strong, resilient non-woven glass mat that is coated with flexible, SBS polymer-modified asphalt. RUBEROID 20 is designed for new roofing and recover applications as well as in the construction of flashings. RUBEROID 20 is an ideal base or interply roofing membrane in modified bitumen systems including GAF Composite Roof and 20/30 systems.