Abstract: A composite sheet material especially suited as a roofing material is disclosed. The sheet is a composite of extruded top and bottom layers. The top layer is formed by extrusion of a mixture of cured rubber particles dispersed in a matrix of polypropylene. The bottom layer is formed by coextrusion with the top layer of a mixture of calcium carbonate and cured rubber particles dispersed in a matrix of polypropylene. The method of fabricating the composite sheet material includes trimming longitudinal edges of the material with powered circular blades as it moves between chill rollers and a pull roller assembly. The material is spooled with minimum winding tension so as to prevent tension forces from being set in the material.