Wood-plastic composite is a composite material lumber or timber made of recycled plastic and wood wastes. It’s most widespread use is in outdoor deck floors, but it is also used for railings, fences, landscaping timbers, cladding and siding, park benches, molding and trim, window and door frames, and indoor furniture. Manufacturers claim that wood-plastic composite is more environmentally friendly and requires less maintenance than the alternatives of solid wood treated with preservatives or solid wood of rot-resistant species. Resistant to cracking and splitting, these materials can be molded with or without simulated wood grain details. Even with the wood grain design these materials are still visually easy to distinguish from natural timber as the grains are the same uniform color as the rest of the material. Well-known trade names include Tech-Wood, Trex, JER Envirotech, CorrectDeck, NewTech, and Weatherbest.

Wood-plastic composite is still a very new material relative to the long history of natural lumber as a building material but can be substituted in most instances. Besides being highly resistant to rot, the major advantage of this category of building materials is its ability to add another stage of upstream use to materials previously considered waste lumber. Although these materials continue the lifespan of used and discarded materials, and have their own considerable half life; the polymers and adhesives added make wood-plastic composite difficult to recycle again after use due to the many impurities in such a compound.