Timber Rising

Wood buildings are not only the Pacific Northwest’s heritage—they’re also its greener, taller future.

Written by Brian Libby

Renderings of Hacker Architects’ new First Tech Federal Credit Union headquarters in Hillsboro, Oregon, show how exterior paneling of varying widths and heights can be deployed to soften the volume of a large CLT building. From a distance, double-height panels disguise the number of floors and minimize the structure’s size to make its five stories look like only four.

Designed by Vancouver’s Michael Green Architecture, the 7-story T3 building (the name stands for “Timber, Technology, Transit”), in Minneapolis’s North Loop, is the largest mass timber building in the US. At right, a model of Lever Architecture’s Framework building.

Historically, the word "Skyscraper", called to mind monoliths of glass and steel towering amid major metropoles such as Chicago and Manhattan.

Few people have thought of wood—usually considered a lowrise, organic material choice—as part of a soaring cityscape. Yet next year, Portland’s Lever Architecture will add the wooden Framework tower, now rising in its hometown, to the picture. It will be the first all-timber high-rise ever constructed in the United States.

The 12-story, 90,000-squarefoot project is made from gluelaminated columns and beams, with a core and floor and ceiling panels of cross-laminated timber (CLT). It is the result of months of testing and close collaboration with state officials. “It’s really a catalyst project,” says Thomas Robinson, Lever’s founder and the project’s designer. Over the past year, the firm has successfully proved that Framework, built using its signature CLT— an engineered wood panel product made from layers of lumber glued together in alternating directions—can withstand fire. “We had to show that a CLT building could burn for two hours and still stand, in the unlikely event that the sprinklers failed and the fire department didn’t come,” Robinson says. “But now that we have, it’s changing the conversation about what’s possible.”

CLT was introduced in the early 1990s in Austria and Germany and went into mass production in the early 2000s, primarily in Europe. It’s quickly been embraced as a sustainable building material: wood naturally sequesters carbon, and, unlike steel and concrete, CLT does not require a carbon-intensive manufacturing process. As North American interest grew, builders began to import CLT from Europe, and soon local mills were churning out the material as well.

The Pacific Northwest in particular seized upon the new option: bountiful timber is available here, and a major earthquake has been forecast to strike in coming decades. “Wooden constructions perform way better seismically,” explains John Hemsworth, principal of Vancouver’s Hemsworth Architecture. “They are significantly lighter than traditional concrete structures.” Hemsworth, who often works with CLT, recently designed the wood-framed Upper Skeena Recreation Centre arena, now going up in Hazelton, British Columbia.

CLT projects also offer a streamlined onsite construction process that borrows its efficiencies from prefab techniques. “Wood can go up a lot faster,” says Jonathan Orpin, founder of timberframing firm New Energy Works, based in Portland and Farmington, New York. “You’re manufacturing offsite and assembling it with a crane in two days instead of 10.” Traditional concrete and steel buildings require specialized onsite manpower, and lengthy build times accrue significant costs. But with wood, Orpin says, “we’re basically bolting together large wooden LEGO sets.” As a result, developers are embracing timber framing for major commercial projects such as the T3 office building in Minneapolis, designed by Vancouver’s Michael Green Architecture and currently, at 224,000 square feet, the largest mass-timber building in the United States.

CLT’s introduction to North America hasn’t been completely seamless: in March, a CLT panel installed in subflooring at Oregon State University’s new Peavy Hall gave way, and a third-party investigation is seeking to confirm that a manufacturing flaw, rather than an inherent failure of CLT, led to the collapse. Builders also note that CLT construction makes creating big volumes of interior space tricky: the material can span only limited distances, and, because CLT doesn’t match the thermal performance of concrete and other types of masonry, it can add to a building’s heating and cooling costs.

Nonetheless, wood is proving itself a worthy price competitor to concrete and steel because of its condensed construction requirements and its accessibility as a material. “In the past, if you compared concrete or steel to timber, the timber didn’t stand a chance,” says David Keltner, a principal with Portland’s Hacker Architects, which designed First Tech Federal Credit Union’s headquarters in Hillsboro, Oregon. “But steel and concrete are getting more expensive, while wood is more available, especially in this region. Now, with more plants in the US, you can get it a little more affordably.” Yet the case for timber buildings ultimately transcends CLT’s practical application. People just seem to love them because wood elicits a strong sense of connection. “It’s that emotional response,” Keltner says. “When you walk into a wood building, you just feel good about where you are. It’s a real material that was once alive, that has tactility and variegation. You don’t have to do math or use a spreadsheet to justify it.”

Michael Green’s T3 building offers 224,000 square feet of office and retail space, as well as parking, and its more than 3,600 cubic meters of exposed mass-timber columns, beams, and floor slabs call to mind the heavy-timber construction used in the city’s older buildings.

Hemsworth Architecture's wood-framed Upper Skeena Recreation Centre arena, now going to Hazelton, BC, demonstrates that wood is a viable structural system for recreation centers when innovative design and engineering are factored in. The exposed wooden elements will be complemented by durable and efficient materials; concrete masonry, cast-in-place concrete, and galvanized metal.

People respond to wood buildings and tend to take better care of them. When people connect with a building, it lasts."

-- John Hemsworth, Architect