Mass timber construction has gained popularity as clients and architects seek to reduce embedded carbon in projects and design unique and inviting natural environments.

Derived from a sustainable source, mass timber offers employees health benefits leading to greater productivity and well-being, according to studies. Minneapolis has been among the leaders in mass timber with the T3 office building in the North Loop.

Despite escalating costs, many clients still embrace mass timber for its attributes. Four architects recently discussed mass projects they recently designed at the state’s American Institute for Architects (AIA) conference in November.

The projects included two offices, a government service agency and a school. In all cases, the architects said they had clients who embraced mass timber despite cost concerns, project hiccups and supply chain surprises. They all said the appeal of wood remained strong because of its durability and innate biophilic qualities.

The largest completed project showcased was the 35,000 square foot Blake School Early Learning Center in Hopkins that houses pre-K, kindergarten and first grade classes. Opened this fall, the school has been submitted for Leadership in Energy and Environmental Design (LEED) Gold level, a recognition awarded by the United States Green Building Council.

Structural engineer Lauren Piepho said the Blake School property featured a small forest near the school that made mass timber appealing. The Blake School incorporates the “Reggio Emilia Approach” to education that encourages environmental stewardship and sustainability.

The Blake school “has a very big commitment to strong connection to nature,” she said. “They have the kids outside in nature every day.” The HGA team thought “mass timber seemed like a really great fit from the get-go” as a way to link the school to the nearby forest and the outdoors, Piepho said, and Blake’s leadership agreed.

The mass timber pricing package from Bell Structural Solutions, however, came in higher than expected, leading HGA to remove plans for wood decks while keeping glulam timber columns and beams that it could locally source. Floors and ceilings would be steel and concrete, Piepho said, with a steel deck roof. Mortenson handled the construction.

“We felt that that really retains the core of the design and returns to the heart of what we were trying to do,” she said.  “We still see these beautiful wood beams and columns and the project was more manageable for the owner.”

Doing an entire project with mass timber may be too expensive but wood can still work when incorporated with steel and concrete. An analysis showed a reduction in embedded carbon over a traditional school building. “We were able to come up with a great compromise here,” she said. “It looks fantastic and we were able to give the client what they wanted.”

Sebastian Joe’s Ice Cream Café owners hired Christian Dean Architecture to build an office building in Linden Hills community of Minneapolis. Architect Jessica Harner said the owners embraced the idea of mass timber, sensing it would attract tenants and create neighborhood goodwill for the 44 Commons office building next to its Upton Avenue South location.

Christian Dean reached out to Woodworks, created by the Wood Products Council, for information on mass timber before hiring River Falls, Wisconsin-based A.M. Structural Engineering as the general contractor.  StructureCraft of British Columbia served as a consultant. During the planning, Harner and her team added a tube steel beam around the second level to add lateral stability and run the exterior walls past the timber floor plates to allow for a brick façade.

Harner said Zeman Construction Company acquired the wood and handled building the office. The company scheduled 24 weeks for the 17,000 square foot, four floor office. The project took just seven weeks and cost $32 a square foot, a considerably lower price than achievable today. The client “is really happy with how things turned out,” she said.

Alliance principal and lead designer Ernesto Ruiz-Garcia spoke about the 32,000 square foot Washington County Central Services Center.  Kraus-Anderson will manage construction after the bids have been completed and rewarded for the $30 million center. A major component of the building will be the license and passport center.

Government buildings are “not usually inspiring spaces,” he said. “I think what’s really most unique about this project is the county wanted to change that. What’s also unique is, honestly, how easily we got to the mass timber answer early on.”

The county wanted a “pleasant” environment for delivering services to constituents. Washington County sees itself as being connected to nature, Ruiz-Garcia said, which made the idea of mass timber acceptable. But the county had never done a mass timber project, which has higher costs, and had to publicly bid the building, which did not allow a contractor to come in early to help.

The Alliance asked the structural engineering firm Meyer, Borgman and Erickson to disclose the most efficient mass timber grids. Using the information, architects created a two-story glass-enclosed central space adjacent to an exterior civic plaza. The main entrance connects to the DMV, a passport center, an elections polling center and space for community corrections, health and public health.

Scheduling proved a problem. Some bidders had never done public bidding and needed to be educated, and then didn’t qualify to participate anyway. And then came a surprise. StructureCraft, which also worked on the building, informed Ruiz-Garcia that the glulam spruce would be coming from Austria.

“I questioned StructureCraft about how sustainable is this?”, he said. The company told him the wood supply came within budget, had better quality than competitors and received a sustainable forest certification. Ruiz-Garcia added that the main takeaway from the project was the challenge of bringing on new contractors late in the process due to the public bidding required of government work.

HGA design architect Joe Mollen presented a case study of a 611,000 square foot Sub-Zero Fabrication facility in Cedar Rapids, Iowa. Now under construction, the building will have an office portion and four entrances highlighted by mass timber.

Mass timber reduced embedded carbon by 89% over steel in the office of the building. Mollen said Sub-Zero considered mass timber but had too many concerns about moisture content leading into the plant based on its experience in another plant. Instead, HGA suggested mixing concrete with sustainable materials to reduce embedded carbon and creating a solar ready roof that may have panels installed after construction.

Mollen said the timber portion has gone to bid. “Even though mass timber was a relatively small portion of the project, the office was really nice size for mass timber we really learned a lot throughout this,” he said.

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