Mass timber is at a crossroads. Cross- and glued-laminated timber, and the material's ilk with potential for massive builds, are at the center of a growing ecosystem of architects, manufacturers, contractors, and consortiums who attended the last month's International Mass Timber Conference in Portland, Ore.
The industry’s economics are promising with analysts citing mass timber’s nearly $2.5 billion share of the global construction industry by 2027. Another metric closer to home for conference organizers is the event’s growth. This year, the seventh annual International Mass Timber Conference drew more than 3,000 attendees from 39 countries, up from 2,100 attendees last year hailing from 33 countries. In 2022, Arlington, Va.–based Trifecta Collective in partnership with New York private equity firm GreyLion acquired the conference, as well as its bellwether annual report, from the Forest Business Network for an undisclosed sum.
Two big questions related to scale drove the agenda and many of the side discussions this year. The first often elides glossy coverage of architects in blogs and Sunday magazines: Can we successfully manage forests to realize mass timber’s greatest ambition to increase the volume of its projects?
That’s a matter of agricultural limits around supply and demand, but it’s also a matter of ownership with divergent interests among private forests, public land trusts, tribal governments, and forest certification organizations and their applicants. Some observers have a dim view that these issues will get resolved. Others see the notion of scaling up as an impossibility in the first place. In the days leading up to the conference, the head of an Austrian civil engineering institute claimed mass timber will never be mainstream because there aren’t enough mature trees to fuel its ambitions.
The second question about scale is broader than the first, and perhaps more encouraging: Can mass timber’s prefabrication, quick installation, and its industry’s improving claims for affordability help solve problems that require a rapid and repeatable solution such as, say, affordable housing? The answer depends on who you ask.
“There’s no reason why it shouldn’t be affordable,” says Andrew Waugh, director and co-founder of London–based Waugh Thistleton Architects. “We do an ongoing analysis of our buildings, which [number] 30 now, and the mass timber itself never takes up more than 21 to 24% of the budget, from supply to erection. If someone tells you their budget problem is mass timber, they’re just blaming mass timber for some other problem.”
Waugh’s firm has been working with mass timber since 2003 and recently completed the Black and White Building, an office tower that opened in London’s Shoreditch neighborhood last year and earned a place as the tallest mass timber edifice in the city. Unlike many mass timber buildings, whose architects make concessions to concrete for a two-story plinth or steel for some of the more demanding spans, the Black and White Building uses cross-laminated timber floor slabs, glued-laminated curtain walls, and laminated veneer lumber for its framework.
Still, Waugh says, what matters is livability, which other architects designing workplace environments feel is an important environmental standard to observe, just as it has always been for the home front. “What’s exciting about the Black and White Building for me is that it’s incredibly low carbon without feeling like it’s a big compromise or suffering,” he says. “We’ve managed to build somewhere that’s lovely to be in.”
Starting Close to Home
Architects at the vanguard of practice have often looked to the scale of the individual house as an ideal place to test ideas. (Think of Le Corbusier’s Maison Dom-ino, or Frank Lloyd Wright’s Usonian Houses, or Charles and Ray Eames’ Case Study Houses.) Mass timber is no different, despite the tall buildings that steal the spotlight away from steel. Single family residential design presents a unique opportunity to answer the scale question of affordable housing because it can be a vital laboratory to test how materials work and, more important, test how the supply chain that’s vexed so many architects and contractors over the last three years might ideally operate.
Jennifer Bonner has been the owner-architect of two cross-laminated timber homes—Haus Gables, a single-family house in Atlanta, and Blank House, a Portland, Ore., residence slated for completion in June of 2024. Both projects are scaled small, but both are also meant to be proving grounds for other architects looking to do work in this vein at multiple scales.
The technology is there, Bonner says, so now it’s a matter of willpower.
“Scalability,” she says, “works when you have automated tools that help both manufacturing and building. Tools we all have access to.”
Bonner, founder of the firm MALL and an associate professor of architecture at Harvard University Graduate School of Design, spent five years researching and building Haus Gables, explaining that cross-laminated timber has reshaped her approach to design.
“This is a good direction for American homes to go in,” she says. “Tall buildings make sense for mass timber now, but we also have to make single family homes and small multifamily homes work with CLT, too.”
Conference organizers seemingly agreed with Bonner, and curated sessions on housing, money, and supply chains, as well as keynotes around three key claims: job creation can drive social equity, forestry restoration can drive environmental stewardship, and savvy financing can drive economic vitality.
“We’re motivated by doing good and by healing the planet and helping people, and that’s an unusual skillset for an industry,” said Michael Green, AIA, founder of Vancouver-based Michael Green Architecture during his keynote address to attendees. “The best way to design with mass timber is not to force structure to work with design but to make design work with structure. That’s how we make it affordable and make it smart.”
Conference keynotes and sessions were both implicit and explicit about the classic triple bottom line of sustainability—defined by people, planet, and prosperity—but it was about more than co-opting business school theory. It’s an important playbook for mass timber as a movement that’s now mature enough to have its precedents and its north stars.
A-P Hurd is a Seattle-based advisor and founder of SkipStone, a consultancy that works with public, private, and non-profits to solve what she calls “thorny real estate challenges.” Presenting on a panel about affordability, Hurd noted reinforced that neither equity, stewardship, nor financing is more than a formula. It represents a multi-year and, ideally, a multidecade commitment—especially in opportunity zones where owners’ tax benefits don’t kick in for 10 years after their equity investment.
“We had investors who were in for 10 years, but then we’d be selling a 10-year-old building, which has this net effect of creating a commitment among investors for high-quality construction that has to be viable in the long-term,” she said. “A mass timber building is a 100-year or 200-year building.”
Facing Industry Realities
In the Venn diagram of mass timber’s design concerns and industry realities, Susan Jones, FAIA, of Atelierjones wields influence that continues to define discussions about mass timber’s value. Her own Seattle residence, CLT House, completed in 2015, has been heralded as a “wooden wonder,” and her self-described “code nerd work”—with colleagues whose fondness and reverence for her is palpable—is credited with strengthening mass timber’s value proposition via the International Code Council’s 2021 International Building Code.
Jones’s latest project, Heartwood for Seattle’s Capitol Hill neighborhood, is an eight-story, 126-unit building for residents earning 60 to 100% of the area household median income. It’s a beacon for the “missing middle” decried by economists, and it’s the industry precedent for the IBC Type IV-C allowance for heavy timber construction with a two-hour fire rating, which Jones authored.
Notably, Heartwood—Jones’ prototype for nationwide, repeatable, middle-income, mass timber multifamily housing that may be scaled to different needs and circumstances—also leverages the efficiencies mass timber has found in prefabrication.
“I am committed to the Cascadian Bioregion, which is everything within 500 miles of where I design and build. I love my European colleagues and the materials they use, but I am committed to using what’s around me while fostering a new method of building everywhere,” Jones says. “In terms of Heartwood, it can be repeated in lots of regions in the United States. We’re not going to make a dent with 126 units. But we can make a dent with more Heartwoods.”
Heartwood raises another point about scalability, which is not to consider the total amount of wood available in the world, but to understand what’s possible at the regional level. The key to making a dent with more Heartwoods, then, is about understanding transference from biome to biome. If one possible goal of the mass timber industry is to have a robust supply network of responsibly harvested wood in any region where there’s suitable material, that might offer a clue about how to modulate demand.
Geography is perhaps the biggest factor outside of forest management that will determine the industry’s success in the long run. If you ship a container too far, you stand a good chance of negating the embodied carbon benefits you might have otherwise realized on the project. If you fail to fully understand the microclimates of your site (or perhaps underestimate the effects of climate change), you stand a good chance the product won’t perform very well, negating the operational carbon benefits.
Then there’s moisture, mildew, critters, and pests. It is wood, after all. (During one housing panel, Leander Moons, an architect who has worked in Zanzibar, spoke about the challenges posed by termites. The solution, he says, is to lift the building up, and use copper and aluminum strips to discourage infestations.)
Termites aside, mass timber’s architects, owners, manufacturers, and contractors individually seem primed to address questions of forest management and affordable housing’s urgent demands. Whether that can be a coordinated industry capability is another question.
"When we have two intractable problems like lowering our carbon footprint and creating more affordable housing, instead of seeing them as individual challenges," says Jones, "we should make them bigger and expand the perimeter of the solution set.”