Cutting-edge Timber Technology

The new cross-laminated timber Design Center building goes up at UMass Amherst last winter; it’s quite a contrast to the appearance of the concrete building beside it. Photo by Emily Kingston / New England Forestry Foundation

A new breed of building appeared on the UMass campus in Amherst this past winter. In a landscape full of concrete, brick, and stone rose a four-story wooden frame, fitted together like a piece of Ikea furniture.

It’s an architectural anomaly, yes, but the 86,000-square-foot Design Center’s true distinction is its contribution to softening climate change. Wood that’s harvested sustainably has a substantially smaller carbon footprint than steel or concrete, and carbon that would otherwise be released into the atmosphere when a tree dies is sequestered in finished wood products. As such, architects estimate that this building offsets carbon in the atmosphere by roughly the same amount in a year as taking 500 cars off the road.

“The building is basically a carbon storage tank....Wood is the original carbon fiber,” said Peggi Clouston, a wood mechanics professor at UMass and a driving force behind the project. The Design Center is the second building of its kind in New England.

Suddenly, wood construction has gone from quaint to cutting-edge. The new technology – called cross-laminated timber, or CLT – is exciting architects, woods-economy boosters, and sustainable-forestry advocates. Architects and engineers worldwide are racing to see who can build the tallest wooden structure. The current record holder is a 14-story apartment building in Bergen, Norway, but a 24-story building is going up in Austria. Last September, the U.S. Tall Wood Building Prize Competition awarded its first $3 million prize, which was shared between a 10-story building in New York City and a 12-story building in Portland, Oregon.

Closer to home, the University of Maine is hustling to complete testing of a hybrid engineered wood panel that officials hope will be well-positioned to capture business in the East Coast construction industry. (The panels used at UMass came from Chibougamau, Quebec, nearly 700 miles and a country away.)

Cross-laminated timber technology was developed in Switzerland and refined in Austria during the 1990s. The material is essentially supersized plywood made of crisscrossed layers of dimensional lumber. It’s strong enough to serve as a structural element and can be delivered to jobsites with window openings and fastener holes precut; speed of construction is one of CLT’s selling points for builders.

But it’s the carbon-storage capacity that gives CLT its sex appeal.

Trees breathe in atmospheric carbon as they grow, storing it in roots, branches, and trunks; if harvested for timber, the carbon then stays locked up in long-lived products like furniture and buildings. “It’s a very compelling story,” said Clouston – particularly with architects, who are early decisionmakers in the choice of building materials. “It’s better for the environment, but that isn’t the whole story. Money speaks.”

The introduction cost of CLT was nearly its undoing.

Informed by her roots in British Columbia and her three-decade career in wood engineering, Clouston had advocated for a wooden building at UMass for years. But a cost comparison with steel-frame construction jeopardized the wood option until it was rescued by an additional $3 million secured by then-Congressman John Olver. The extra millions were justified as necessary to cover the added costs of introducing a new building technology: the code-variance requests, supply-chain challenges, and caution and inexperience at all levels.

The Design Center helps to showcase CLT technology through the intentional visibility of wood in the design. “It’s a demonstration structure, so everything is exposed,” Clouston said. “Being in this building is going to be a completely different experience. . . . Wood really feels different.” One goal of the project was to spread the word about CLT: a plethora of photos, text, and videos on the UMass website help to document the building material and process, and the building’s story is being told by those who know it best, including Boston-based architecture firm Leers Weinzapfel Associates and Suffolk Construction, Boston’s largest building construction company. The departments occupying the new space include, appropriately, Building and Construction Technology, Architecture, and Landscape Architecture and Regional Planning. For her part, Clouston speaks at conferences on the topic as often as she can.

“We’re trying to have a ripple effect,” she said.

“We’re trying to talk to people who can make a difference: architects and engineers.”

The prospect of growing demand for these high-tech wooden buildings has some folks in Maine talking of opening a CLT manufacturing plant in the state, which desperately needs new forest products industry jobs given the recent closures of at least four paper mills and two biomass plants.

Cutting-edge Timber Technology Image

Russell Edgar, lab operations and wood composites manager at the Advanced Structures & Composite Center, beside a stack of cross-laminated timbers. Photo by Lee Burnett / Forest Works!

The current center of CLT talk in Maine is the Advanced Structures and Composites Center at University of Maine at Orono. The lab pioneered wood-composite glulam bridges in 2001, then moved on to offshore wind development. I recently toured the airplane-hangar-sized facility with Russell Edgar, lab operations and wood-composites manager. He showed me how CLT panels earn their grades in a vertical viselike machine that delivers a crushing weight that’s equivalent to that of a locomotive engine. Testing has found that CLT panels made from Maine-grown red-spruce lumber break more easily than those made from Quebec-grown black spruce or West Coast-grown Douglas fir, according to Edgar.

But it turns out that one of the most durable combinations is red-spruce lumber sandwiched around a core of laminated strand lumber (LSL) made of pressed aspen chips. The spruce handles the compression and tension forces on the outside faces, while the LSL panel handles the rolling sheer force inside. “It kind of made sense; it was the perfect match,” Edgar said. The hybrid panels meet or exceed the standards of the American National Standards Institute, although the ultimate arbiter will be the marketplace, he said.

“Where does a hybrid CLT fit?” he mused. “Which grade is there market-demand for?”

The materials testing is one of the many early steps in developing a wider market and, ultimately, determining whether there is enough demand to justify a CLT manufacturing plant in Maine.

“We’re behind the curve, for sure,” said Edgar, referring to the three Canadian CLT mills and one Oregon mill already in operation. But after attending a mass timber research workshop in Wisconsin last November, Edgar has become bullish. “There is serious momentum behind this. . . . This is going to happen. There’s a critical mass of architects and engineers. It seems like it’s inevitable. The only question is how much time it will take to get a plant built.”

It will be a slow process, predicts Lloyd Irland, an economist and forest industry consultant. “The amount of ballyhoo per square foot that this is generating is infinite,” said Irland. “We’ve heard breathless examples of individual buildings. But we don’t have any idea what the demand will be. Really, new building concepts don’t happen overnight.”

While beautiful “prestige” wooden buildings like the UMass Design Center capture imaginations and help to promote awareness of new technologies, it’s far more numerous commercial structures that will drive the need for a CLT plant, he said.

“For every architect that’s excited, there’s a half-dozen others saying, ‘my clients don’t want that.’ A lot of building clients are more interested in function, service, and cost. They’re not interested in stunning.” Patrick Strauch, executive director of Maine Forest Products Council, sees the tall building competition, recent federal legislation accelerating research and development of CLT, and strong demand for bio based products as all pushing a “renaissance in the use of wood, coming full circle.” An example of that renaissance is a new affordable housing project in downtown Portland, notes Senator Angus King, I Maine. Avesta Housing used prefab wood frame construction – instead off conventional concrete and steel – in constructing a four-story, 42-unit, multifamily housing project in one of the city’s low-income neighborhoods. The design won an award for lowering the cost of housing.

“It’s kind of back to the future,” King said.


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