Choosing the “greenest” wood
By Boone Guyton on 03/16/2009
A woody dilemma
I was looking out at the view from our Candler home at a ridge that had been partially clear-cut, and it inspired me to become serious about reducing the board feet of wood used in our home-building business. It felt hypocritical to criticize someone for harvesting the trees in my view, while at the same time demanding wood from the builders’ supply, which in turn had once been in someone else’s view.
One of the basics of green building has always been the use of sustainable materials. Wood is a renewable resource—as long as it comes from a source that is managed for sustainability. There has been a lot of attention given to forests, both as sources for human consumption and for the essential services they provide to the ecosystem. We now realize our forests must be healthy if our planet is to sustain and support us. According to the N.C. Department of Environment and Natural Resources, “We rely upon our forests for a wide variety of resources, we value them for a range of social and cultural reasons, and they are an essential component of a healthy planet.”
What is forest health?
Think of a forest as a tree-dominated community of plants, animals and microorganisms. These living beings interact with each other and with the soil, water and the climate, DENR scientists explain. When the community is healthy and properly managed, trees, for example, provide such benefits as protecting soil from erosion, reducing runoff and improving water and air quality.
There is a growing awareness of the need to maintain healthy forests while providing wood products for humans, both now and for future generations. The predominant third-party certification system is the Forest Stewardship Council. FSC certifies that the wood in a product has been sustainably produced. Key FSC principles include the protection of forest watersheds, soil and indigenous species, as well as restrictions on chemical use and limits on genetic engineering and ensuring that fair-labor policies are upheld and local populations have influence over forestry operations.
More than 100 million hectares of forest distributed over 79 countries worldwide were certified to FSC standards in April 2008. Products that are FSC certified show up in Home Depot and Lowe’s stores regularly, though getting entire framing packages for home building is still difficult. There are also other certification programs, such as the American Forest and Paper Association’s Sustainable Forestry Initiative, which was started by the forest industry in response to FSC, but is not based on a required third-party audit.
The principles of reducing, reusing and recycling can be applied to the use of wood in home building. According to the National Association of Home Builders, the average home in the United States is 2,330 square feet, up from 1,400 square feet in 1970, and uses about 17,000 board feet of lumber or about 85 trees. Reducing the size of a house and simplifying the geometry is the easiest way to reduce the embodied energy overall and the board feet involved in the construction.
In residential construction in North Carolina, wood framing is the predominant method of home building, and there are specific ways this wood can be used more efficiently. Optimal value engineering or advanced framing techniques can reduce the board feet in the framing of a house by 11 to 19 percent. Replacing large dimensional lumber with engineered lumber like roof trusses, floor trusses, I-joists and micro-laminated beams reduces the board feet used by substituting engineering for material. There are also structural insulated panels, which greatly reduce the amount of board feet in the building envelope. Stressed-skin panels can save between 25 and 50 percent of the framing lumber used in a typical house.
There are also methods, such as insulated concrete forms, that substitute concrete for wood framing in an insulated, stay-in-place form. These have embodied energy costs, but must be considered when looking at alternatives to wood.
There are options for recycled and reclaimed wood from companies that deconstruct buildings and mill the wood into new products, as well as companies that salvage wood that had been lost in shipping years ago and can be recovered from the bottom of rivers. One example is Old Growth Riverwood from Wilmington, N.C. Often there are opportunities to deconstruct or salvage from local buildings, if you have the time to work at it. We once used wood from an old bowling alley to construct the countertop in a house.
Buy local wood
Probably the best wood choice is the sustainably managed, locally sourced wood. We are fortunate to have many local sawmills in our area, some that are stationary and some portable mills that will bring the saw to the site. Then, there are kilns to dry and mills to manufacture the wood into finished products from flooring to moldings. There is more scheduling and time involved in seeing the process through from standing tree to finished wood, but the unique and unquestionable sustainability of the products that employ local people is an important added value.
Also, local wood has much less embodied energy from transportation. We have used local walnut, cherry, poplar, Virginia pine and locust for moldings, flooring, decking and cabinets. Take note: There is a new business in town, the Asheville Treecyclers, whose mission is “to cooperatively and sustainably utilize our downed urban trees; to provide locally grown and manufactured sustainable wood products; and to work cooperatively to further the awareness and practice of sustainable urban forestry in our community.”
Turning what was otherwise a waste product or destined to be ground to mulch into a higher-value product is an innovative solution—much like turning restaurant grease into bio diesel. Making choices about wood use and wood products impacts our ecosystems, and good choices contribute to the sustainability of our forests. You’ll find many local businesses that are part of the solution in this directory.
Boone Guyton is a partner in Cady and Guyton Construction, a HealthyBuilt Home builder. He is also a founder and current board member of the WNC Green Building Council.