Wood Plastic Composites (WPC)

Wood Plastic Composites or WPCs – the combination of wood and plastic – are gaining popularity as a safe, environmentally sustainable and long-lasting material for use in outdoor decks, fences, railing and window frames. Today, WPCs can be found everywhere from National Parks to your neighbor’s backyard.

WPCs offer a wide range of advantages over alternatives such as pressure-treated lumber and naturally durable cedar or redwood: weather resistance, long service life and lower maintenance, to name a few. These products also play a role in developing a more sustainable future: many WPCs use recycled plastic and wood as raw materials in the manufacturing process.

Tests of WPCs in harsh outdoor exposures have unveiled one potential downside to this miracle material: wood fiber not completely encapsulated by plastic is, by its very nature, food for fungi.

Tests show that, left unprotected, the wood fiber in WPCs may be susceptible to wood destroying organisms such as decay fungi and termites. Standard laboratory tests evaluating the performance of commercially-produced WPCs against decay fungi have exhibited weight losses of between 10 and 20%. Because typical WPCs have a wood:plastic ratio of 50:50, this loss equates to a reduction of between 20 and 40% of WPCs’ wood component.

But there is also good news from the laboratory and the field: Borogard® ZB – used in preservative treatment of WPCs – provides long-lasting protection against decay fungi.