Wood Building Materials Are Sustainable and Renewable
Everything old is new again, especially when it comes to construction. Suddenly, architects and builders around the world are discovering that wood building materials are sustainable and renewable — and beautiful,too.
Wood has many advantages over traditional building materials such as concrete or steel. Trees absorb carbon dioxide as they grow. When trees are made into building materials, that carbon dioxide remains sequestered in the finished products. When wooden building materials reach the end of their useful life, they are often be repurposed or recycled into new products. All that stored carbon dioxide is kept out of the atmosphere virtually forever.
Wood Is Sustainable And Renewable
A study by Architecture And Design and published in the Journal of Sustainable Forestry finds that the world’s forests contain more than 400 billion cubic yards of wood, but relatively little of that is turned into wooden building materials. Globally, there is a virtually inexhaustible supply of wood.
The world has come to rely on concrete, steel, aluminum and brick building materials, but the study finds that 16% of all the fossil fuel consumed every year is used to turn those raw materials into construction products. Using wood and specially engineered wood products instead would drastically reduce global carbon dioxide emissions and fossil fuel consumption. Managed properly, this could be done without loss of biodiversity or carbon storage capacity.
Architect Michael Green of Vancouver says “The Earth grows our food. The earth can grow our homes. It’s an ethical change that we have to go through.” Australian architect Alex de Rijke adds, “The 18th century was about brick, the 19th about steel, the 20th about concrete, and the 21st century is about wood.”
New Wood Construction Products
Wood as a construction material has gained favor with many builders and architects thanks to new technologies. The most promising is cross laminated timber (CLT) — a process that resembles plywood but on a larger scale. According to the American Wood Council, cross laminated panels are made from industrial dried lumber stacked together at right angles and glued over their entire surface. They are almost as strong as steel, retain their static strength and shape indefinitely and allow the transfer of loads on all sides. Panels are prefabricated based on the project design and arrive at the job site with windows and doors pre-cut. CLT panels can be made up to 54 feet long and 10 feet wide and may contain 3, 5, 7 or more layers.
Architect Michael Green has completed a 6 story CLT building in Prince George, British Columbia known as the Wood Innovation Design Center, but he says CLT wood construction products could be used for buildings up to 30 stories high. He calls them “plyscrapers.” Based on Green’s work, the provincial government has enacted a regulation that requires the use of wood as the primary building material in all new provincially funded buildings. Australia’s largest building contractor, Lend Lease, has constructed an 8 story apartment complex in Melbourne using CLT construction materials.
Prefabricated wood products go up in 30% less time and create less waste on the job site, which saves money for contractors and building owners.
New Products Need New Tools
CLT panels can be custom manufactured to meet the needs of a particular building design. But to maximize the environmental benefits of building with wood, shouldn’t the structural framework be made of wood, too?
Meet Reinhard Sauter. He is the founder and president of Sauter Timber in Rockwood, Tennessee. His manufacturing facility uses a special 6 axis CNC machine to make CLT timbers up to 20 feet long for the structure of wooden buildings. His customers buy enormous Douglas fir logs in the Pacific Northwest or pine logs from the South and have them trucked to the Sauter Timber facility to be turned into CLT products. The finished beams have their ends milled precisely so they can be assembled quickly and accurately when they arrive at the job site.
Sauter also imports CLT panels up to 39.5 feet long and 3.9 feet wide from Europe to serve as the side walls and roof panels of wooden buildings. Why those precise dimensions? Because otherwise they wouldn’t fit in a standard shipping container, says Mr. Sauter. Because the CLT panels are so strong, roof beams only need to be placed every 20 feet, he says, which saves time and money for builders.
It wouldn’t do for Sauter Timber to be housed in a traditional steel frame building, so Reinhard Sauter has built the largest wooden commercial building in the United States for his business. It also serves as a “proof of concept” display for those who might be skeptical about building with wood.
Why Not Use Whole Trees?
Whole Trees of Madison, Wisconsin, in cooperation with the Forest Products Laboratory of the U.S. Department of Agriculture (USDA) Forest Service, has pioneered a new method of turning entire trees into trusses, beams and joists in building construction. These are trees that the Forest Service routinely harvests as part of its is routine thinning program and would be discarded otherwise.
Whole Trees then dries and treats the trees to protect against shrinkage and pests. Pound for pound as strong as steel in tension, the unmilled timber requires less than 2% of the energy needed to make concrete and steel building materials. “We are positioned to occupy a large niche in the approximately $13 billion U.S. sustainable structural systems market,” president Amelia Baxter told Forbes magazine recently.
Wood Is Good For Your Health
Architecture and Design reports on a new study by Planet Ark entitled “Wood – Housing, Health, Humanity.” The study finds that “being surrounded by wood at home, work or school has positive effects on the body, the brain and the environment and can even shorten hospital stays through reduced recovery times.”
That’s especially important because people spend as much as 90% of their time indoors where they cannot interact with nature on a regular basis. “The studies examining the effects of wooden rooms and furnishings clearly demonstrate that the presence of wood has positive physiological and psychological benefits that mimic the effect of spending time outside in nature,” Planet Ark says.
“The feelings of natural warmth and comfort that wood elicits in people has the effect of lowering blood pressure and heart rates, reducing stress and anxiety and increasing positive social interactions. Wood products within a room have also been shown to improve indoor air quality by moderating humidity.”
There is one more benefit to building with wood and it has nothing to do with structural strength or carbon sequestration. Wood adds beauty to the interior and exterior of any building. It is warm to the touch and pleasing to the eye. When you consider all the advantages of wood, it’s no wonder that more and more architects are calling for buildings made of wood for structures of the future. As Alex de Rijke says, “The 21st century is about wood.”
Photo credits: Architecture And Design