While 20th century architecture was arguably defined by the innovative use of concrete, steel and other modern materials, it looks more and more like 21st century design will be defined by one of the most traditional building materials of all: timber.

To be clear, it’s not log cabins we’re talking about here. Thanks to major technological advances in the past few decades in the realm of engineered wood products, 3D computer modeling and digital fabrication, today’s timber products are sturdy, reliable and, perhaps most importantly, more sustainable than comparable materials.

The key innovation in the space has been the development of mass timber, a category of building materials that includes modern engineered wood products such as cross-laminated timber, or CLT panels, and glue laminated timber, also known as glulam columns and beams. These materials are increasingly popular in design- and sustainability-focused projects, notes Erica Spiritos, mass timber preconstruction manager for Swinerton, the 131-year-old commercial design and construction firm.

“With each announcement of a new or completed project in a few pioneer cities, awareness and excitement about mass timber is growing across the country,” Spiritos says. “We have completed three projects, have four in construction, and the number keeps growing. We are currently tracking 8 million square feet of mass timber products being built in the U.S. in the next couple of years. That’s significant.”

The key to mass timber’s sustainability, she explains, is the use of small-diameter, fast-growing trees.

“WoodWorks calculated that it would take Oregon timberlands 46 minutes to grow the wood for a 156,000 square-foot office building. Demand for lumber, coupled with new forest management practices that support a broader array of ecosystem services, is incentivizing sustainability and having positive impacts on our forest land.”

The benefits of mass timber don’t stop there, though. The flexibility of the material allows for faster builds and up to 75 percent fewer deliveries to a job site, Spiritos says.

And then there’s the labor advantage, says Corey Martin, architect and principal at Hacker Architects. “In markets that have really big labor shortages, you can take advantage of the precision manufactured product to be more efficient with your field installation crews. Parts are brought to the site, ready to be assembled. So you can have a team in the 10- to 15-person range assembling a typical office building structure, as opposed to the 50-plus-person team that kind of site usually needs.”

“It’s the ability to create enduring value” that excites Noel Johnson, principal at developer Cairn Pacific, about mass timber. “I think you can be creative,” he says. “That’s why I do it.”

“I think it’s telling that a lot of architects are designing and moving into their own timber buildings,” says Eric McDonnell, principal at Holmes Structures. “Quite simply, they’re the best places to be.”


Panel Discussion: The Case for Mass Timber

At a Feb. 5 forum hosted by the Portland Business Journal, panelists Corey Martin, principal at Hacker Architects, Eric McDonnell, principal at Holmes Structures, Erica Spiritos, mass timber preconstruction manager at Swinerton, and Noel Johnson, principal at Cairn Pacific, discussed how use of mass timber can make projects more cost-effective, more sustainable and more attractive. The discussion was moderated by Timm Locke, director of forest products for the Oregon Forest Resources Institute. Comments have been edited for length and for clarity.

What does the term “mass timber” mean to you?

 Martin: I think we’re in the process of figuring that out. There have been a lot of different ways of building with wood over the years, and lately we’ve been focusing on certain products like CLT (cross-laminated timber), but a lot of new technologies and ideas are coming out of the lumber industry. You could say anything that’s built out of wood of a certain size that has a certain thickness to it qualifies as mass timber.

Johnson: Mass timber can certainly be defined by its physical properties, but it’s also something more intangible. On a societal level, it can be a reaction to carbon pollution, or it can be an interest in getting connected to where materials are coming from or how products are made, or who it’s being made by, or the craftsmanship of it. It’s a neat, super broad response to certain issues with current building materials.

Spiritos: We’ve been building with timber of significant dimensions for hundreds of years. The difference is that when we build with mass timber products today, we’re building with engineered wood products that are typically glued-together lumber coming from small diameter trees, whereas a hundred years ago we were using large diameter, primarily old-growth trees to make those heavy timber components.

What are some common mass timber materials, and how do they differ from other timber products?

McDonnell: First of all, I think it’s great that we’re using the term “mass timber,” because when cross-laminated timber first came out, a lot of people were kind of fixated on CLT. But mass timber is actually a broader set of materials. Glulam, or glued laminated timber, for instance, is typically made up of two-by materials adhered together, with all the fibers running in strong directions, basically creating beams or columns. With cross-laminated timber, on the other hand, the orientation of the fibers tends to be perpendicular. You’re gluing the materials together into big panels, like 10-by-40-foot panels. There are some newer products as well, like mass plywood products. And then there are other products that have been around for a long time, such as LVL (laminated veneer lumber)-type materials and parallam (parallel strand lumber) materials. All of these products that are made up of smaller pieces of wood formed together into bigger pieces are considered mass timber, as well as traditional big, heavy timbers.

Why is mass timber getting so much attention these days? 

Spiritos: Mass timber responds to some of civilization’s most pressing issues today. We’re talking about a way of building that addresses issues around climate change, that addresses issues around densification of cities due to population growth and rapid urbanization, that addresses need for housing in cities that already exist. I recently learned from the Director of the Council on Tall Buildings and Urban Habitat that we need to build a new Chicago every every month somewhere on the planet in order to accommodate global population growth. I think to myself, “How are we going to do that? Are we going to do that in a way that is fast and safe and uses renewable resources, and boosts local economies?” Mass timber enables us to do that.

Johnson: I think that with my parents’ generation, there was a lot of excitement about post-tensioned concrete and what it could do. And then in my grandparents’ generation, steel was the big breakthrough. So there are periods of time when the built environment industry is thinking creatively and there’s a lot of energy. I think the mass timber boom is analogous. But the best part is that these large mass timber buildings that were built in my great-grandfather’s generation and before — they’re all still there. They’re not rusting. They don’t have cables inside that we have no idea how they’re going to fare in 300 years because it’s a technique we’ve never done before. Timber buildings are proven. If you go to other nations that are older than ours, we see these buildings, and they’re just so alive and thriving, and they’re beautiful structures.

Spiritos: I grew up in New York City – the concrete jungle. I moved to Portland in large part to be closer to nature, and to me, mass timber is a way to bring nature into cities. I am a city-dweller, to be sure, and that’s where I feel comfortable. And I think there’s no denying that the trajectory of our civilization is toward cities. But with that kind of urban lifestyle and our increasing reliance on technology, mass timber can serve as a vital reminder of humanity’s interdependence with the natural world.

Why do you prefer to work with mass timber materials?

Martin: As a designer, wood is just an amazingly beautiful material that has this great quality of connecting people to the landscape. And of course one of my goals in design and architecture is to connect people to nature — no matter what kind of building I’m designing. Even if I’m designing a building for downtown New York, I want to figure out a way to connect people to nature, and using wood (and mass timber) is one of the ways we’ve always been able to do that. I’m also a sculptor, though, and I’ve spent years sculpting mass timber. There’s just something really tactile and meaningful about digging into a piece of wood. So as I’m thinking about designing buildings, I’m thinking about them as architectural spaces connecting people to nature, but also as sculpture and art. And the great thing, for me, about wood is that it combines those two aspirations into one practice.

What are the advantages of using mass timber for a project?

Johnson: For one thing, it can be quite profitable. From a developer’s standpoint, there are two schools of thought about how to make money in real estate. One is to try and squeeze costs as much as possible on every level. The other is to try and build something that’s a little bit better, something a little bit unique and new. Mass timber falls into that latter category. I think when you create value through that mechanism, when it’s a true expression of creation, you can actually have a profitable project that everyone enjoyed working on, as opposed to a project that was technically profitable, but that no one really enjoyed working on or that the community doesn’t really profit from.

Spiritos: From a construction standpoint, the technology around mass timber enables us to take a natural material that’s inherently imprecise due to the hygroscopic nature of wood, and transform this material into a precision-manufactured component that allows us to build 12 or 18 story structures with ease and reliability.

Martin: Mass timber can definitely be faster than other methods. Of course, it depends on the team and the project, but since it’s a precision manufactured product and there’s a lot of technology that we can take advantage of, we’ve found that mass timber can be a lot faster. We can CNC the pieces in the shop and bring them to the site and assemble them much more quickly, because a lot of the work is done off site. That’s definitely an advantage.

Spiritos: We’re also finding that a lot of the cost savings associated with the mass timber comes from thoughtful consideration of how the mass timber structure integrates with other building systems, whether that’s the foundation or the facade or the fire sprinkler system, and then integrating the prefabrication process into those other building systems. For example, on the project for First Tech Federal Credit Union, we were able to achieve a 4 percent savings over a more traditional steel structure and delivered the structure four months ahead of schedule, because we simplified the interface with the building envelope, and because we had a lighter foundation, among other savings.

In what ways is mass timber more sustainable than concrete and other modern building materials?

Spiritos: Wood, by chemical composition, is about 50 percent carbon by dry weight. When you cut down a tree, that carbon remains in the lumber or the glulam beam or the CLT panel for as long as that material exists in that building. So what we’re doing when we use timber is shifting the carbon sequestration from the forest into the city and then sequestering new carbon in the forest by growing new trees.

Martin: Whereas other materials actually release carbon in their production.

Spiritos: Right. Exactly. And it’s kind of counterintuitive, but the healthiest forests are actually the ones that are generating revenue. In the United States, most of the forestland that’s logged for lumber and other forest products are privately owned. And to maintain any piece of land, no matter the function it’s serving, you need some kind of revenue generation. So it actually makes sense that cutting down more trees is the way to incentivize and ensure sustainability in our forests and improve wellbeing across those lands. So instead of the policy being “cut fewer trees, use less wood,” I think the more sustainable policy to promote forest health is “grow more trees, use more wood.”

McDonnell: I think the most compelling thing is that wood is the only structural material that we have that is grown with just sun and water. There’s something pretty special about that.

How does mass timber affect the way you design and build?

Martin: There’s a labor component that I think shouldn’t be understated. Precision manufacturing and machining of the parts can reduce the amount of people it takes on site, which is important in markets that have a really big labor shortage, like San Francisco. For a building that’s 150,000 square feet, there’s a team of people in the 10 to 15 range, versus the 50 or so that it usually takes to erect a structural system for the building. And they’re doing it very quickly and quietly in a smaller amount of space because they don’t have to have all of the gear and all of the equipment on site that they would normally need. But that’s just one aspect that makes mass timber more appealing. As Erica said, to build one Chicago a month is going to take a lot of people. And the number of people required to build buildings isn’t going to go down. We’ll need more and more labor. So how can we make it more efficient?

McDonnell: I think that’s probably one reason you’re seeing even more of these types of buildings being built in Europe, where the labor market is even more restrained than ours. As our labor market moves more in that direction, I think we’ll see increasing interest in mass timber.

How can mass timber buildings improve conditions for occupants?

Martin: There have been a lot of studies done on the importance of what we call now biophilia, which is basically the impact of nature and natural materials on human beings. And tests have shown that people are more productive and take fewer sick days at work when they’re in workspaces that are better designed and more humane. So with mass timber designs people can be happier at work, but it also affects the bottom line, because companies that are hiring can get better returns on their labor force by designing and providing spaces that are more humane, and ultimately more productive, for their workers.

McDonnell: I also think it’s very telling that a number of the architects we work with are designing and moving into their own timber buildings. It’s great to go to those offices and spend time in those conference rooms. They’re the best places to be.


Meet the panelists

Corey Martin, Principal,Hacker Architecture

Corey Martin joined Hacker Architecture in 2011, and his design leadership has guided some of the firm’s most notable, award-winning projects incorporating wood, mass timber, and CLT. As an Oregon native, Corey is strongly influenced by the unique relationship between the natural and built environment of the Pacific Northwest, and he has received wide acclaim for creating modern buildings that display a particular sensitivity to the natural environment, daylight, spatial dynamism, and craft. His work has received numerous national and international awards for excellence in wood design and construction, including Lakeside at Black Butte Ranch, the Unitarian Universalist Fellowship of Central Oregon, and First Tech FCU.

Eric McDonnell, Principal, Holmes Structures, Portland

Eric McDonnell is an industry leader in the development and implementation of mass timber structural systems. A native of the Pacific Northwest with a natural affinity for timber structures and a strong background in wood engineering, Eric has traveled the world to absorb the latest in mass timber technology. Shaped by work experiences in San Francisco and post-earthquake Christchurch, he also brings a knowledge of resilient seismic design to his projects. He has coupled these strengths to present cutting-edge solutions with enhanced seismic performance to numerous mass timber projects. Eric is also committed to advancing the profession through collaborative research efforts, including participation in code committees, development of mass timber design guides and speaking engagements.

Erica Spiritos, Mass Timber Preconstruction Manager, Swinerton

Erica Spiritos has long been interested in the design of urban environments in ways that honor the natural resources on which our lives depend. Following her Civil & Environmental Engineering studies at Carnegie Mellon University, Erica discovered mass timber structures and their potential benefits to the construction industry. She joined a major mass timber supplier and became a cornerstone of the mass timber movement in the Pacific Northwest, educating the AEC industry and facilitating solutions to deliver eight projects, including both the tallest and the largest CLT projects in the USA. With Swinerton, Erica provides project-specific expertise to support appropriate and optimal mass timber design, estimating, BIM integration and procurement strategy.

Noel JohnsonPrincipal, Cairn Pacific

Noel Johnson has worked in commercial real estate since 2001, sourcing, capitalizing and building innovative, institutional-scale housing, office and retail developments. Cairn Pacific is a full-service urban development company with experience ranging from neighborhood infill projects to large downtown high-rises. Johnson was one of the early leaders in the mass timber movement, developing buildings such as Clay Creative, The Hudson and 120 Clay in the Portland area to attract millennial workforces, while providing product differentiation to investors. He has also focused on redevelopment of urban brownfields, using unique public-private indemnity structures to enable institutional-quality investments.

Moderator: Timm Locke, Director of Forest Products, Oregon Forest Resources Institute

As OFRI’s Director of Forest Products, Timm works to increase awareness among designers, builders, and policymakers in Oregon of the many advantages of CLT and other mass timber products. He is active in Oregon’s Wood Products Working Group and an organizer for the International Mass Timber Conference, which will be held in Portland in March. His efforts have helped establish Oregon as the epicenter of the mass timber movement in the U.S.

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