CertainTeed Flintlastic Ultra Poly SMS Base Sheet is designed for use as a base sheet for both hot and cold applied SBS modified bitumen or built-up roofing systems. It is suitable for use in the construction of various types of roof membrane assemblies for both new construction and reroofing, over a variety of substrates. Also suitable as a mid ply in multi-layer systems or as a torched-down base sheet over a gypsum coverboard. Flintlastic Ultra Poly SMS Base Sheet will provide additional strength when used as the first ply over nailable, non-nailable and insulated substrates. In addition, it will perform as a venting base sheet when spot mopped over approved insulations.