Wood's New Wave

Advances in computer software and computer technology make wood more viable as a structural component.
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Nancy B. Solomon, AIA

Given the current sense of urgency regarding global warming, this calculation alone has encouraged increasing numbers of green-minded practitioners to build with wood. Designers, of course, point to wood's many other desirable qualities as well—from being highly renewable to aesthetically pleasing—for additional reasons why they select it.

The caveat is that the wood must be sourced from responsibly managed forests. “We are not talking about clear-cutting,” stresses Peter Busby, managing director of the San Francisco office of Perkins+Will. He notes that the relatively recent increase in availability of sustainably harvested woods at reasonable prices makes environmentally minded practitioners feel more comfortable about specifying wood today.

Resource Management

Because natural lumber is limited in size, and the long-term preservation of our forests is yet another environmental priority, architects working on larger projects are increasingly turning to engineered-wood products to obtain the structural dimensions they need while lowering a building's carbon footprint. Since engineered woods are generally manufactured by pressing together with adhesive smaller, often lower-quality, pieces of wood—from lumber and veneer to strands and particles—the growing cycle for the raw material is much shorter than is needed for natural lumber of equivalent size and strength.

According to Karsh, it can take hundreds of years for a tree to grow large enough to supply solid-wood timber for traditional post-and-beam construction, whereas it takes about 40 years for a tree to supply the 2x6s that are typically used to manufacture glue-laminated timber, or glulam, an engineered-wood product that has been on the market for decades. And it takes only about 10 to 15 years to grow the trees used to produce wood chips for laminated-strand lumber (LSL), another common engineered product. When the life cycle of timber production is shortened, our forests become more productive. “If we manage our forests responsibility, which includes generating products that have a shorter renewal period, we don't risk depleting our forests,” states Karsh.

Engineered woods have many other benefits as well, notes Nabih Tahan, chief sustainable officer of CREE Buildings in San Francisco. For example, they can be manufactured to desired performance standards; are very stable, so they will not twist or shrink; and can be cut to very fine tolerances so components will fit together exactly in the field.

Iconic Forms

According to Busby, Perkins+Will began working seriously with wood about 15 years ago. “It started with wanting the qualitative characteristics of wood,” he recalls. The firm was engaged in designing the Brentwood Skytrain Station in Burnaby, British Columbia, and the goal was to create a warm, friendly, noninstitutional feel to encourage residents to get out of their cars and use public transit. The designers created a curved roof diaphragm out of glulam, and the exposed structural canopy met with great success. “Since then, we have tried to get wood components into every building we work on,” Busby says.

The design team behind the VanDusen Botanical Garden visitor center (opening spread and above) relied on three different computer-modeling programs – Rhino, Revit, and Inventor – to develop the overall roof shape and individual components.

Image courtesy Perkins Will

So wood was a logical choice for Busby when specifying the roof structure for the new visitor center at the VanDusen Botanical Garden in Vancouver. The client wanted a signature building that would increase public interest in its plant collections, bring people in closer touch with natural surroundings, and minimize negative impact on the environment. Perkins+Will responded with a highly organic design based on a native orchid for the 1,000-square-foot building. Its iconic roof, which is covered by extensive vegetation, looks like a flower with undulating and overlapping petals radiating from a central stem.

 

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Originally published in GreenSource.
Originally published in March 2013

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