No, we’re not talking about unseasoned lumber. In this case, “green” refers to reconstituted wood products that have recycled content, low toxicity or other eco-friendly qualities. These products include formaldehyde-free composite wood panels, bio-panels made from agricultural fibers such as sunflower hulls, wheat straw, and sugar cane fiber, arsenic-free pressure-treated lumber, engineered structural wood, and recycled wood/plastic composite lumber.
A good example of an eco-wood product is Homasote, a fiberboard made from 100% recycled paper (mainly newspaper, lottery tickets, and paperback books) with no formaldehyde or asbestos additives. The panels are fully biodegradable, have twice the insulation value of wood, resist insects, water, and mold, and act as a noise barrier. They are typically used as a sound insulator under drywall and other wall coverings.
Formaldehyde-free medium density fiberboard (MDF) is now available. Two of the best known brands are Medex and Medite which are made from waste wood fiber that is a by-product of wood processing and lumber milling operations. MDF can also be sandwiched between wood veneers to create panels with a solid wood appearance. Although heavy, such MDF wood panels excel at furniture applications where flatness and dimensional stability are important. They also save on the use of solid timber and create a healthier indoor environment because of greatly reduced formaldehyde out-gassing.
Traditional engineered wood products such as plywood, oriented strand board (OSB or “wafer board”), glued-laminated timber, wood I-joists, and laminated veneer lumber are an eco-friendly option in the sense that they are generally manufactured from fast growing, underutilized, and readily replenished wood species such as aspen and poplar. Their use helps to reduce logging pressures in older, more valuable forests. In fact, it seems likely that the engineered-wood industry will do more to save our old-growth forests than any other factor, given the overall size of the industry. Unfortunately, the glues and resins used to create these products are typically not very eco-friendly from an air-quality perspective.
For outdoor applications, a very viable eco-choice is manufactured lumber made from recycled plastic and wood. Composite plastic lumber is low-maintenance, arsenic-free, rot proof, and will not crack splinter or chip. It also does not require finishing or sealing. It is ideal for non-structural uses such as decks, outdoor furniture, fences, and landscape borders. Composite plastic lumber is a great way to recycle materials that might otherwise end up in the local landfill.