Taking a Close Look at Composite Lumber
This material is a recycler’s dream, mixing together scrap plastic and wood fiber wood mill sawdust into relatively stable boards that have been used for outdoor decks and railings, garden accents, trim and window frames, and even for interior flooring, to name a few options.
On the plus side, the product requires no painting and little maintenance during its lifetime. Slivers are almost unheard of, and while each board contains a considerable amount of plastic, the finished product has a texture that more resemble wood than some of the cheaper plastic-only predecessors.
Fewer trees need to be chopped down and the cost of hiring a finish painting crew is significantly reduced, as most composite lumber comes pre-finished. Composite wood manufacturers will usually claim that products produced with recycled wood/plastic lumber are more durable than conventional preservative-treated lumber, adding that these products contain no toxic chemicals such as those used in conventional treated lumber – a very important consideration.
Composites have as many different formulas as there are products, but generally recycled wood/plastic composite lumber consists of a 50/50 mix of wood fibers from recovered saw dust and waste plastics that include high-density polyethylene and PVC.
The material is formed into both solid and hollow profiles. Recycled wood/plastic composites are typically more rigid than 100 percent recycled plastic lumber because the wood fibers act as reinforcement.
It is the plastic that encapsulates and binds the wood together to resist moisture penetration and degradation from fungal rot.
There are some negatives to consider, however. Some recycled wood/plastic lumber products can weigh considerably more than standard lumber products. Like other plastic products, recycled wood/plastic lumber can become more flexible in hot weather and more rigid in cold weather than other decking materials. The plastic character of the boards is usually more brittle than wood. Most carpenters have learned the hard way that a deck screw driven to hard with a drill gun can go right through the board. Not all of the finishes are as durable as one might like, The boards have been known to change into inconsistent color patterns due to sun, weather or rain.
There is also the issue of cost. Composite lumber has a price point equal to higher quality wood. According to Toolbase.org, composite wood prices out at about $2.00 a linear foot.
Regardless of the price issue, Toolbase.org adds, “By eliminating or reducing the amount of virgin materials used in production, and by making use of existing materials in its manufacture, recycled wood/plastic composite lumber contributes to the efficient use of resources. In addition, the lumber is not impregnated with chemicals in the manner of preservatively-treated (sic) lumber.”