This specification establishes requirements and test methods for materials, impact strength, appearance, surface flame spread, and windload resistance of siding products manufactured from polypropylene material. The use of polypropylene recycled plastic in this product shall conform to the specified requirements. The siding shall be made principally of polypropylene compound, prepared from polypropylene homopolymer or copolymer. The polypropylene compound shall be compounded so as to provide the heat stability and weather exposure stability required for the siding market application.