Wood-plastic composite (WPC)

Overview

Wood-plastic composite (WPC) is wood flour or fibre mixed with a thermoplastic, most commonly polyethylene (PE), but also polypropylene, PVC or PLA, and extruded into boards. Covema of Milan invented it in 1960 and it reached decking in the early 1990s (Wikipedia). It looks like a grey or brown board with a moulded grain. Furniture makers use it for outdoor pieces that should never need refinishing; it is not a fine-furniture material.

Pros

• Does not rot (Wikipedia), so there is no annual sealing or staining.
• Works with ordinary woodworking tools and can be bent (Wikipedia).
• Colour is built in, so no painting is needed.
• Uniform board with no knots.
• Wood content is commonly around 50/50 and can reach 70% cellulose (Wikipedia).

Cons

• Behaves mechanically like the polymer, so it is weaker and less stiff than wood and can creep under load (Wikipedia).
• Absorbs water, and the wood particles are susceptible to fungi (Wikipedia).
• The polymer is vulnerable to UV and some formulations stain (Wikipedia).
• Hard to recycle again after use, with a higher fire hazard than wood (Wikipedia).
• Expensive: Angi puts materials at $10-18 per sq ft, well above treated pine.

Variants and subspecies

• PE-based: by far the most common (Wikipedia).
• PP, PVC or PLA-based: less common formulations.
• Wood content: from about 50/50 up to 70% cellulose.
• PVC decking: a different, wood-free material; Angi prices it $5-15 per sq ft.

Working and finishing

Wikipedia says WPC is workable with ordinary woodworking tools and can be bent. Cut it with a carbide blade and follow the manufacturer's guidance on fasteners, gaps and expansion, since polymer content changes with temperature. We did not source tool-wear or fastening data. It needs no painting; Wikipedia says some formulations stain, so clean spills.

Staining and finishing colour

It is not stained. Colour is mixed in at extrusion, giving greys and earth tones (Wikipedia). Wikipedia notes UV vulnerability and that some formulations stain, so check the maker's warranty for sun and spill exposure.

Sustainability and handling

WPC combines wood waste with plastic. It is hard to recycle again after use, and Wikipedia lists a higher fire hazard than wood. We have not verified an embodied-carbon figure, so we make no carbon claim. Moisture uptake can feed fungi in the wood fraction (Wikipedia). Handling is ordinary lumber handling; dust is plastic and wood.

Popular projects

Decking and railings above all, plus fence boards, outdoor bench slats, planter boxes and cladding where low maintenance matters more than looks.

Buying notes

Sold mainly as decking boards and rails. Angi gives $10-18 per sq ft in materials for WPC and $5-15 for PVC. Compare wood content, capping, UV warranty and the manufacturer's span tables, and buy matching clips and fasteners with the boards.