1.1 This specification covers polyolefin-based plastic lumber products for use as exterior residential decking boards. 1.2 Plastic lumber products are currently made predominantly with recycled polyolefin plastics (in par This specification covers polyolefin-based plastic lumber products for use as exterior residential decking boards. Plastic lumber products are currently made predominantly with recycled polyolefin plastics (in particular high-density polyethylene) wher