Fast-N-Stick HD-Base Mechanically Attached Base Sheet is made from tough composite reinforcement of non-woven polyester strengthened with a glass fiber scrim in both machine and cross directions that is coated with select SBS polymers and premium quality asphalt. A dual release selvage that incorporates an adhesive SBS coating provides for complete self-adhesive lap seaming of Fast-N-Stick HD-Base. The top surface of the product is covered by a thin layer of micro-perforated film, which disappears upon heat welding of the cap sheet. The bottom surface is sanded to prevent sticking in the roll. Fast-N-Stick HD-Base is a strong “lay flat” base sheet intended to be used as a mechanically fastened base sheet in the Fast-N-WeldTM System.