From salvaged wood to plastic lumber, advice on choosing the most earth-friendly decking material If you’re thinking of adding a deck to your home or replacing an old one, you’ll find plenty of options for building materials. Which is the most earth-friendly? The answer's not that simple. Each one has its share of pros and cons. Here's what you need to know about the choices out there today. New Wood Redwood and cedar are traditional decking choices, being naturally resistant to rot. More recent deck-worthy options include hardwoods like ironwood, or ipe, (pronounced “EE-pay”) from South America. But be sure to select woods that are certified by the Forest Stewardship Council (FSC) as sustainably harvested to be sure you are not supporting clear-cutting. But, points out Marc Richmond, vice president of Working, a green-building consultancy headquartered in Boulder, Colorado, “If FSC-certified lumber or exotic hardwood must be trucked from far away, unfortunately, we still have transport-related pollution issues.” Safer Sealants Wood decks require periodic sealing to keep them looking good and wearing well. |
And even sustainably grown wood—typically pine or fir— can be pressure-treated with an infusion of toxic chemicals after it’s harvested to deter wood-eating organisms. The industry has switched from the use of chromated copper arsenate (CCA) to less-harmful copper combined with the fungicide azol. Still, pressure-treated lumber is not biodegradable. Cost per linear foot: 2-by-6 construction heart-grade redwood, $1.50; locally grown cedar, $2 to $2.50; ipe, $3; ironwood, $2. Maintenance: Yearly cleaning and sealing, occasional staining. Longevity: 15 years if well-maintained.
Reclaimed or Salvaged WoodIf you can easily get your hands on high-quality salvaged or reclaimed hardwoods, that can be the best option of all, says Richmond, because it conserves stands of old-growth timber. Salvaged lumber can be difficult to find, though. Search online for suppliers in your area or ask your local lumberyard to recommend a source. Depending on its age, recycled lumber is likely to have been treated with CCA. The substance has been in use since the 1940s and was widely used beginning in the 1970s. Cost per linear foot: Varies, depending on the source.
Maintenance: Yearly cleaning and sealing.
Longevity: 15 years if well-maintained.  Wood CompositesWood composites mix waste-wood fiber with either polyethylene or high-density polyethylene made from plastic grocery bags and milk containers. The mixture is molded into boards to create pest-proof decking material that doesn’t warp or splinter. Some brand names are Trex, Easy Care, Nexwood, TimberTech, Fiberon, LP WeatherBest, Epoch, and CorrectDeck. On the front end, these products are earth-friendly because they keep scrap wood and plastic out of landfills. But once the deck reaches the end of its lifespan, it isn't recyclable or biodegradable. The waste fiber is encased in plastic, so insects, fungus, and microbes can’t get at it to decompose it. Also, strength remains a challenge for the industry. Although composite decking has great compressive strength, it lacks tensile strength. In other words, it takes a lot to crush the material, but it bends easily. As a result, it cannot be used for deck framing. Instead, composite decking is typically installed on standard pressure-treated wood posts, beams, and joists. Cost per linear foot: $2 to $3.
Maintenance: There is no need to stain or reseal composite decking. Clean it once or twice a year with a bucket of soapy water and a bristle brush, followed by a squirt from the garden hose.
Longevity: Warranties range from 10 to 25 years. Plastic LumberPlastic lumber is made from 100 percent high-density polyethylene recycled from plastic grocery bags and milk containers, with no wood fillers. Brand names include Trimax, Carefree, and Durawood. Since it is solid rather than hollow, it can be cut in the same way as wood, with no special tools needed. Plastic lumber is earth-friendly in that it repurposes plastic that probably would have otherwise ended up in a landfill. According to manufacturers, plastic lumber is 100 percent recyclable. But it’s not biodegradable. Avoid polyvinyl chloride (PVC)—often labeled with the number 3. PVC is a leading source of dioxin, a potent environmental toxin. Composites react to fluctuations in temperature rather than moisture. To prevent buckling, a 1/8-inch gap is required between boards if you install the deck in hot weather. Stay away from mixed plastic products because each type expands and contracts at a different rate. Maintenance: Cleaning is the same as for wood composites.
Cost per linear foot: $2 to $3.
Longevity: Warranties vary from 10 to 25 years. | 
