Trex is the name brand of one type of composite wood material. Because of the glue used to hold the fine, sawdust-like grains together, Trex has far different weight characteristics than most comparable decking materials.
Trex and other composites like Practiwood, NewTech and TimberTech are produced by binding waste sawdust together with a virgin PVC or polyethylene adhesive.
Trex is approved for use in non-structural items like handrails and decking. Trex must be regarded only as a covering when used for decking and applied over a substrate of wood or metal struts.
Trex has a nominal density of 60 pounds per cubic foot for solid boards, and 2-by-2 Baluster Trex is approximately 64 pounds per cubic foot.
Trex weighs approximately twice as much per cubic foot as common softwoods like treated southern pine, cedar and redwood.
Hardwoods are much denser than softwoods and Trex's weight per cubic foot is nearly the same as oak, applewood or ash.