EXOSTK 40MIL Peel and Stick Underlayment is a premium-grade, self-adhering underlayment. EXOSTK 40MIL is engineered to exceed rigorous industry standards. It features an SBS-modified Bitumen compound laminated onto a non-woven polypropylene fabric making it an effective secondary barrier against water and moisture under asphalt shingles, metal roofing, slate, and tile. Select grades of polymers enhance the adhesion to diverse substrates such as plywood, OSBs, wooden particle boards, concrete, and metal surfaces. The robust polypropylene mat offers exceptional anti-slip properties, improving walkability on sloped roofs. Combined, the adhesive compound and the durable surface provide superior temperature resistance and heightened durability against weathering.