APP 80 Glass Base is a smooth-surfaced APP modified bitumen roofing base sheet designed to be heat-welded. It consists of select asphalt, modified with atactic polypropylene, and reinforced with a non-woven glass fiber mat. The combination results in a flexible, durable, smooth-surfaced base sheet. APP 80 Glass Base membranes are ideal for both new construction and re-roofing applications as a base sheet in multi-ply and flashing applications.