BY BRIAN LIBBY
This week Lever Architecture founder Thomas Robinson dropped by the Center For Architecture to speak with the Portland chapter of the American Institute of Architects' Committee on the Environment about a new generation of timber-framed buildings rising around the world, especially in Europe but increasingly in the United States. Two upcoming Lever-designed office buildings, Albina Yard and Framework (the latter of which is not to be confused with a Works Partnership-designed building of the same name), rely on timber framing and in particular a new generation of cross-laminated timber (CLT).
Last September, the unbuilt design for the 12-story Framework building in the Pearl District (which is developed by Project and Home Forward and set to break ground early next year) won the US Department of Agriculture’s Tall Wood Building Competition, which included a $1.5 million research grant that Lever is using largely on a series of tests to prove that Framework and this kind of cross-laminated timber framing (including glulam columns, beams and ceilings) is safe and viable.
As Robinson detailed in his talk, this is an exciting turning point for timber-framed buildings, whether it's for sustainable or seismic or aesthetic reasons. In all cases, there is a compelling case for a future in which steel and concrete-framed buildings are no longer the norm. Timber framing is not a new technology, of course. It's as old as architecture itself. But the ability to build taller and more fire-safe than ever before is turning out to be a game changer.
Although the renderings Robinson showed of these two upcoming projects were beautiful, my enduring memory is a photo he showed of a ceiling in the house on Cape Cod that his grandfather built in the 1920s. "It was all Oregon timber," the architect said. " It’s not a big house. But for me it’s probably the reason I became an architect. The reason was the experiential quality of the space was so rich. I had this desire to re-create it. I think it has sort of come full circle with the projects we’re doing today."
Robinson titled his talk "Forest To Frame," which he said borrowed from the farm-to-table movement in food: the idea that CLT can "start the conversation between how growth in cities connects to rural economic development in a place like Oregon. The reason our cities are healthy is because of the land-use planning of the 70s, I think. How do you re-establish that connection? Oregon has some of the most native timber land in the world. This is one of the best places in the world to grow timber. I don’t know if every architect knows that. And it’s growing in its native habitat. Even if you’re just using Oregon wood, it’s being harvested in its native habitat. Even if it’s not FSC certified, using a local renewable resources like this is a really good thing"
The architect also noted CLT's less environmentally damaging manufacturing process and its relation to fighting climate change. "You’re basically sintering rock in a kiln to make Portland cement. With steel you have a furnace that uses tons of energy to make it. Wood is a renewable resource. Half the weight of wood is carbon, so it’s a way to store carbon. Instead of a forest rotting or catching on fire, that carbon is being sequestered in a building for 50 to 100 years." But, he added, "It comes down to exactly how that wood was fabricated and sources. You need to source it from a managed forest to make sense."
The architect prefaced his discussion of CLT at Framework and the under-construction Albina Yard (the first instance of an office building using domestically fabricated CLT) with mention of two wood-heavy projects that preceded them (both of which were also developed with Project): the Union Way shopping complex in the West End (which carved a wood-festooned shopping alley through the middle of an early 20th century auto garage) and the Arthouse residence hall for Pacific Northwest College of Art.
Before Arthouse, the firm's first ground-up project, "I’d never done a large wood structure before. Everything had been steel or concrete. I was dubious of doing five floors of timber over a floor of concrete. But as I got into it with Walsh [Construction], we realized there were these advantages: the lightness, the precision, the speed. No one would know this is a timber structure, but it fundamentally is."
Although wood-framed buildings have been around for centuries, it's improved connections between the pieces and better engineered wood products that are making them popular again, as well as new hybrids of wood with steel and concrete, and a heightened appreciation for wood buildings' resilience. "Trees are the tallest living things on the planet, and they withstand massive forces and winds. There’s a limit to just wood, but where you get to really higher structures is hybrids of concrete and wood. There are taller wood buildings like these being built all over. With Framework, it’s a little more uncommon in that it’s all wood."
Perhaps what's most exciting about CLT is its seismic performance and durability. "Wood is inherently strong. It can take huge loads," Robinson went on. He described Framework as ""basically a post-CLT tension system. You think of my forearm as a 140-foot-tall solid wall. We take the CLT and connect it together with dowels or stiffening agents, and then we tension it in the center with steel rods. The idea is that whole wall can rock slightly in an earthquake, up to three percent, and the steel rod pulls it back. It allows us to withstand larger seismic forces than a conventional building. We believe we can not just withstand a larger earthquake but create a building that’s reparable after an earthquake. Most of the larger steel and concrete buildings after a large quake would have to be torn down. In a lot of the testing, like the research done in New Zealand after the Christchurch earthquake where they were looking at more resilient systems, this was one of the answers they found."
Union Way's wood all came from a forest three hours outside of Portland in Boardman, Oregon. "I remember driving past this forest on the way to The Dalles a couple times and going, ‘What is that?’ What was this forest?' That motivated us through some folks we knew to contact the owner directly and look at using it," Robinson explained. "We actually went to the forest's owner; they harvested a certain amount of wood and milled it to our specifications. Why do it? Because it was really inexpensive. But it was also FSC certified."
The $1.5 million USDA grant for Framework is mostly going to a series of tests "to show that our building meets the performance criteria of the code with an alternative structural system," he said. "We have to do like 30 tests: fire, seismic, acoustic. We did a two-hour fire test about a month ago. It withstood a fire for two hours and actually could have gone longer." How is it that wood won't burn? Well actually it does, but the bottom layer acts as "a sacrificial layer," Robinson explains. That bottom layer burns, but the fire doesn't spread to the other layers of the CLT."
For Albina Yard, which has been described as the first speculative office building in the country using domestically manufactured CLT, Robinson saw the project as a chance to overcome some of the issues with permitting that could have delayed its later, larger sister building, Framework. "We had to get the city and state to agree to figure this out. I didn’t want to do that for the first time on the larger project, but at this smaller scale it seemed doable," Robinson explained. Using CLT instead of tongue and groove wood brought "the ability to do these larger more continuous spans. It’s cantilevering five feet in each direction, so you can span 10 feet no problem."
The architect also emphasized the paramount importance of working with fabricators and suppliers.
"If you’re serious about doing this, you have to understand and almost start with the supply chain," he said. "Right now it’s not robust. It’s a new industry. DR Johnson’s the first but there will be others. We have Structurelam in British Columbia and they’re also doing work here. There’s a manufacturer in Quebec. But everything else is coming from Europe. To do this type of work, you have to go from the detail to the fabricator. They may say you have to find a different way. Without that level of coordination, we would have been in big trouble. You can have a great idea, and it may not be feasible, so you have to change the idea to make it work, and that’s OK."
Of course these two Lever buildings are among many wood-framed and in some cases CLT-utilizing projects in Portland or by Portland firms. Earlier this week, for example, the Oregon BEST CLT Design Contest gave top honors to a SRG Partnership-designed parking garage in Eugene framed with CLT, and runner-up to Carbon 12, an eight-story mixed-use condominium in Northeast Portland designed by PATH Architecture. And though it's not CLT-framed, I was quite wowed a few weeks ago touring the Works Partnership Architecture-designed building that's also known as Framework, this one at NE Seventh and Davis, with its wood framing and ceiling visible through the glass facade almost like a ship in a bottle. That's part of what's exciting: not only is wood framing simultaneously a throwback and a new era of architecture in Portland, and not only is it encouraging on a seismic-performance level, and not only is the material a whole lot more sustainable than steel or concrete, but some of Portland's most talented, perennial award-winning firms are embracing it first.