CertainTeed Flexiglas Base Sheet is designed for use as a base sheet for hot asphalt applied, inorganic built-up or modified roofing systems. It is suitable for use in the construction of various types of membranes for both new construction and reroofing, over a variety of substrates. In addition, it will perform as a venting base sheet when spot mopped over plastic foam type insulations. Also suitable as a mid-ply in multi-layer systems. Flexiglas Base Sheet will provide additional strength and improved handling and pliability when used as the first ply over nailable, non-nailable and insulated substrates.