Why is wood used for residential buildings

At least three carbon effects must be tallied up. First, some greenhouse gas emissions are released by the supply chain, starting with forestry. In logging, soil carbon is disturbed and released, plant and wood waste is generated that eventually rots and releases carbon, and emissions are generated by the vehicles and machinery necessary to cut the wood, transport it to the mill, and treat it.

Second, there is some amount of carbon embedded in the timber itself, where it is sequestered in buildings that could last anywhere from 50 to hundreds of years. Though the exact amount will depend on tree species, forestry practices, transportation costs, and a number of other factors, Green says a good rule of thumb confirmed by this study is that one cubic meter of CLT wood sequesters roughly one tonne 1.

Third and most significantly, substituting mass timber for concrete and steel avoids the carbon embedded in those materials, which is substantial. Cement and concrete manufacture are responsible for around 8 percent of global GHG emissions , more than any country save the US and China. The global iron and steel industry is responsible for another 5 percent. Something like half a ton of CO2 is emitted to manufacture a ton of concrete; 2 tons of CO2 are emitted in the manufacture of a ton of steel.

All those embodied emissions are avoided when CLT is substituted. Exactly how those three carbon effects balance out will depend on individual cases, but research suggests that, for all but the most poorly managed forests, the overall impact of using CLT in place of concrete and steel will be a reduction in GHGs.

It allows buildings to be constructed faster, with lower labor costs and less waste. If provided detailed plans by architects and designers, the factory can fabricate, e. It virtually eliminates material waste — there are no door and window cutouts to throw away because the wood was never put there in the first place.

With computer-guided fabrication, wood is placed only where it is needed. Because these prefabricated pieces can be assembled a few at a time, in sequence, with relatively little labor, they can be shipped to the construction site on a just-in-time basis, avoiding massive on-site inventory and minimizing on-site disruption. Construction projects can be squeezed into tight, idiosyncratic urban spaces.

Even tall towers can be constructed within weeks, with low labor costs. Mass timber will help change that. The performance of mass timber in earthquakes has been much tested and tested and tested and has proven remarkably good. While concrete simply cracks in earthquakes, which means concrete buildings must be demolished and replaced, wood buildings can be repaired after earthquakes. Mass timber is also lighter and can be built on urban land, e.

It is appealing on a primal level, a connection to nature. Architect Susan Jones of Atelierjones LLC oversaw the building of one of the first CLT single-family residences — her home of five years in Seattle, built to super-efficient passivhaus standards. It was featured in Dwell Magazine.

Forests in the West have become tinderboxes, in part thanks to climate change and in part thanks to years of poor management. They are filled with trees dead or weakened from pine beetle infestations. Decades of overzealous fire protection have left them choked with closely clustered, small-diameter trees.

The land is being permanently scarred. This has given Franz an idea : use weak and small trees, for which there is no other market, for mass timber. Logs with tops as small as 4. A sufficiently large market for mass timber would create funding for thinning those trees out. As a bonus, Franz wants to use mass timber to build low-cost affordable housing on publicly managed land. Softwood mostly pine, spruce, or fir forests in the US are predominantly found in the Northwest and the Southeast, and the communities that live and work in them have been struggling, especially since the housing crash and the great recession.

New demand for softwood could help reopen some of the closed mills and revive some of those communities, aligning their interests with a Green New Deal-style program of national revitalization.

In his TED talk, Green notes that billions of people worldwide lack homes — a half-million in North America — and will need to be housed in the coming century, largely in cities. If all that urban housing is accomplished with concrete and steel, the climate is hosed. A more sustainable alternative must be found. And wood is the only material sufficiently abundant and renewable to do the job. But Build With Strength is, ahem, sponsored by the concrete industry.

By and large, architects and builders are excited about mass timber, as are timber businesses and communities, timber-state politicians, climate hawks concerned about the carbon impact of building, and city officials looking for ways to accelerate decarbonization and win some good PR. A material that can be grown in abundance, creates rural jobs, reduces construction waste and labor costs, and slows the growth of concrete and steel seems like a win-win-win.

The good-faith reservations that do exist are about the supply chain, and they come in two forms. First, protecting and properly managing forests is a huge part of fighting climate change and preserving a livable world. Intact forest ecosystems provide not only carbon sequestration but ecosystem services, wild animal habitat, recreation, and beauty.

Universities in critical need of student housing have found a fast and economical solution in prefabricated and modular construction. The storey residential tower is home to more than students. The design is deliberately straightforward, demonstrating that timber construction can be a safe and repeatable approach to high-rise construction.

Erected in just over two months, the superstructure has prefabricated exterior wall panels with wood-fibre-and-resin cladding. The five-storey student residence was the tallest building of its kind when construction in and added beds for students. The beautifully illustrated, page publication contains more than 65 innovative wood buildings and projects, including how wood is being used in multi-family residential projects and accommodations.

Four continuing education units have been developed based on the book. They are recognized by the Architectural Institute of British Columbia and are available at naturallywood. Download the Naturally Wood e-book at naturallywood. Delivering affordable housing is an urgent issue across Canada, yet there are ex The DCN stories driving their way to the top spots this week include a large-sca This week on the Construction Record podcast digital media editor Warren Frey sp Work continues at the commercial tower Front Street West in Toronto.

The pr Pre-Bid Projects. This material contains chemicals including formaldehyde, which has been shown to significantly worsen indoor air quality. Forest owners argue that a large-scale move away from wood will actually hurt the environment; without a market for trees, they say landowners have little incentive to grow them and may instead turn their land into farmland or houses.

Around 1 billion trees are planted each year in the United States, according to the National Alliance of Forest Owners.

The forest products industry argues that moving away from lumber would cost jobs in sawmills and manufacturing; they estimate that forestry-related businesses support more than 1 million jobs. Many timber companies even offer discounts to customers whose homes have burned down to offload supply.

Piles of old-growth trees salvaged from burned forests sit in lumber yards around town, he says. One by one, though, they started dropping their commitment to use less flammable materials as contractors told them that they only had the capacity to build with wood. The latest report from the Intergovernmental Panel on Climate Change says the atmosphere will warm by as much as 2.

Meanwhile, the high demand for lumber may be causing more trees to be cut down, rather than fewer. Poachers have cut down at least old-growth trees this year on Vancouver Island in Canada as lumber prices rise. And as fires ravage more of the West, timber salvagers are removing old-growth trees from burned forests, taking advantage of lax post-wildfire rules.

As fire season approaches again this year, timber companies are trying to convince western states that they need to increase logging in order to prevent forest fires.

In the end, it may take the same economic factors that nudged Sean Jennings to push others in that direction. When he was planning his new house, Jennings learned that insurers would not cover it because of its fire-prone location; that persuaded him to seek out non-flammable materials to protect his investment. Because of changes to hurricane building codes in the southern U.

Watson, the builder in Northern California, has been approached by some wineries who have had their fire insurance revoked and are looking for alternatives to wood. But widespread adoption is a long way off.