Ply IV Sheet is asphalt impregnated, glass fiber mat reinforced roofing ply which has been designed to provide superior durability and ease of application. Ply IV Sheet is designed for use in the construction of Elevate Asphalt Built-Up Roof Systems. Ply IV Sheet can be used in conjunction with Elevate Modified Bitumen Base and Cap Sheets to build Hybrid Systems. Ply IV Sheet may be used as a ply in Modified Bitumen and Built-Up Roofing Systems.