The race is on to build the world’s tallest wooden skyscraper—and re-imagine the urban skyline

May 10, 2022, 8:13 AM UTC

Brumunddal is a small Norwegian city on the shores of Lake Mjøsa, about halfway between the capital Oslo and the ski resort of Lillehammer. Until recently, this community of 10,000 was best known as a docking point for the Skibladner, which locals say is the world’s oldest paddle stream ship still in service.

For the past three years, however, Brumunddal has earned a new claim to fame: home to Mjøstårnet, the world’s tallest wooden skyscraper—a record that will probably fall in a matter of weeks. Half a world away, in Milwaukee, construction crews are putting the finishing touches on Ascent MKE, a luxury-residential, mass-timber high-rise that’s scheduled for completion this summer. That wooden structure will soar to 284 feet above the Milwaukee city streets, taking the crown as the world’s tallest, a mere four feet higher than Mjøstårnet.

Losing the record is no big deal, insists Øystein Elgsaas, a partner at Voll Arkitekter, the Trondheim, Norway firm that designed Mjøstårnet. Besides, he notes, there are other mass-timber skyscraper projects planned that will tower over Milwaukee’s Ascent in the coming years. “The most important thing about this project is to inspire others,” he tells Fortune.

So far, mission accomplished.

Climate benefits of wooden buildings

Mass-timber buildings are beginning to transform skylines around the world with new-builds on drawing boards across Asia, Europe and North America. Google parent Alphabet, for example, broke ground in November on a grand, mass-timber office building in Sunnyvale, Calif. And Japanese timber giant Sumitomo Forestry unveiled plans in 2018 for a 70-storey timber-hybrid building, which is poised to break yet another height record.

Climate hawks and city planners consider wood an intriguing eco-friendly building material that could begin to replace at least some of the concrete and steel used in new high-rises and high-density building complexes. Builders see environmental advantages in wooden structures as the more precise construction design produces less landfill waste and noise pollution at the job site. They also tout the cost savings. Wood high-rises can often be erected quicker, and done so with smaller crews. (Incidentally, specialists in the burgeoning field of 3D-printed construction herald their technology as delivering superior speed, cost, and waste-trimming advantages over conventional home-builds, too.) Elgsaas estimates the builders shaved months off the construction time of the Mjøstårnet because so many pieces were pre-fabricated off-site, and then assembled quickly onto the structure like attaching giant Lego pieces to a tower.

Added bonus: wood buildings, like a forest, can function as the lungs of a neighborhood.

“Tall wooden buildings store carbon, preventing it from entering the atmosphere by sequestering it in the building for decades,” says Warren Mabee, a renewable energies expert, and director of the Queen’s Institute for Energy and Environmental Policy in Kingston, Ontario. “In contrast, buildings made of steel and concrete generate large amounts of carbon emissions per tonne of material produced,” he says, referring to that early step in any building phase: the energy-intensive, high-temperature industrial process of making the steal and concrete.

For that reason, and because of the energy expended on heating up or cooling down the massive structures each day for occupants, buildings are one of the biggest polluters, generating nearly 40% of the planet’s CO2 emissions.

To get a glimpse at the future of these giant tree houses, all manner of designers, engineers and architects have been making the pilgrimage to Brumunddal, or telephoning Elgsaas’s small firm to get the low-down on how to build these massive wooden structures. “This building has gotten way more attention abroad than in Norway,” Elgsaas marvels.

‘Glulams’ of Norwegian spruce

The 280-foot-tall (85.4-meter) Mjøstårnet is a lakeside structure that serves as office space, a 72-room hotel and restaurant, and residential apartments. It was built of Norwegian spruce harvested from a forest less than a half-hour drive from Brumunddal; even the elevator shafts are made of wood. (The four uppermost floors sit on concrete slabs, the railings are made of steel, the windows are glass, but everything else—the skeletal core, the facade, the flooring, and furniture—are all milled timber from the nearby forest.)

Inside an apartment at Mjøstårnet.
On the top floor of Mjøstårnet, there is one penthouse apartment and a public viewing terrace.
Courtesy of Voll Arkitekter

The slim, tower-like design is emblematic of these mass-timber buildings. As Mabee points out, these are no vertically-built log cabins. To give the structures strength and durability, they are constructed with layers of wood bonded together with adhesive to create the beams and panels. The technical terms for the key pieces are cross-laminated timbers, laminated veneer lumber, or “glulam” for glued laminated timber.

Last year, Mjøstårnet won the coveted “award of excellence” in architectural design from the Council on Tall Buildings and Urban Habitat, a Chicago organization recognized as the official records-keeper for the world’s tallest and grandest buildings. The New Yorker‘s Rebecca Mead visited the building earlier this year, and called it “an audacious gesture and a proof of concept.” Elgsaas says that Mjøstårnet has become a kind of model for designers interested in using locally sourced materials to build the high-rises of the future.

Voll Arkitekter's Mjøstårnet restaurant.
Interior of Voll Arkitekter’s Mjøstårnet restaurant.
Courtesy of Voll Arkitekter

“Wood is a material that is light. It is environmentally friendly. You can build quickly with it. Maybe we can use it to replace the beams and columns made from reinforced steel and concrete because it’s a very efficient way to stabilize the buildings,” Elgsaas says. He’s not predicting we will see a bunch of mass-timber Mjøstårnet copycats, but “I think we will see more and more hybrid versions” that increasingly use wood.

Lumber price sticker shock

Nobody expects to see 100% wooden skyscrapers towering over steel and glass structures any time soon—if ever. “Mass timber is probably limited in terms of height,” Mabee tells Fortune. But then, he adds, we shouldn’t get hung up on height records. A new generation of designers and architects are beginning to push the boundaries of what’s possible with wood construction for high-rises. “What I suspect will happen is that traditional concrete and steel and emerging mass timber will hybridize as the push for height continues,” he continues. “What we end up with might be considerably lighter and stronger buildings than we have today, but with innovative combinations of steel, concrete, and wood elements.”

Construction of Ascent MKE, the soon to be tallest timber structure in the world.
Work is done on the mass timber Ascent apartment tower in downtown Milwaukee in December 2021. Once completed, the 284 feet-tall tower will be the tallest mass timber structure in the world, according to developer New Land Enterprises.
Mike De Sisti—Milwaukee Journal Sentinel/USA TODAY NETWORK/Reuters

But there are a few boundaries to overcome along the way. For starters, the cost of lumber has skyrocketed in the United States, which could put some developers off these kinds of designs until prices moderate. In any case, Elgsaas and other design experts see wood as a viable building material only in timber-rich countries, and only if harvesting can be done in a sustainable manner. Another issue: local officials concerned about fire-safety hazards will have to be convinced this material meets the most rigorous building standards.

Elgsaas says his team confronted the latter issue in Norway, a country where wood construction dates back centuries, and has otherwise earned widespread trust from the public. Still, he admits, when your plan is to build a wooden skyscraper, “you kind of have to… prove to the (regulators) that this is possible,” he says. To demonstrate the fire-retardant qualities of Mjøstårnet’s glulam beams, he says, they put one into a roaring furnace for two hours. On a Teams call, Elgsaas shared photos of the charred, but intact wooden beam that held up remarkably well under fire, and ultimately convinced the fire marshals it more than lived up to the country’s most stringent fire codes.

The Mjøstårnet opened its doors in March 2019, and Elgsaas still gets asked to present the story of the project and give tips on how similar structures could win construction approval elsewhere. In the years since, his team has consulted on similar projects across Europe, he says, including in timber-rich Germany, Russia, the Netherlands, and Paris.

“The way we see it, since we were the first, we should make it easier for other projects to follow us,” he says.

Each week, Fortune covers the world of innovation in Breakthrough. You can read previous Breakthrough columns here.

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