SBS Premium Base is a superior performing base sheet featuring a blend of SBS (Styrene-Butadiene-Styrene) rubber polymer and high-quality asphalt reinforced with a glass fiber/glass mat laminate. The addition of SBS rubber polymer optimizes the asphalt blend to increase its natural waterproofing properties, adding elongation, elasticity, and flexibility to the sheet. The inorganic fiber glass reinforcement resists moisture absorption. It also provides strength and stability to the product, yielding a membrane that resists natural forces and other factors on the rooftop. SBS Premium Base is designed specifically as a base layer for use with SBS Modified Bitumen Systems and is ideal for use on both new construction and reroofing projects.