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A rendering showing plans for the 21-story Ascent tower in downtown Milwaukee — which promises to be the largest “mass timber” building in North America when completed. (Rendering courtesy of Korb + Associates Architects)
When a building known as T3 opened a few years ago in the North Loop of Minneapolis, it was the largest mass-timber office structure in the country.
Now it stands to be surpassed in Milwaukee by the proposed Ascent tower, which is being developed by a local firm named New Land Enterprises.
These projects are just two among many that promise to take a building technique now mostly found in Europe and move it forward in the U.S.
Proponents of mass timber contend this building technique reduces carbon emissions and has more aesthetic appeal as a builidng material than steel or concrete.
Wood construction also stands to soon play a part in many sorts of plans to reduce carbon emissions. Buildings now account for about 40 percent of all carbon emissions, according to federal and international studies.
The idea that mass timber buildings could be the answer, or part of the answer, is compelling, especially in states where there are healthy forests and real estate professionals who are searching for new ways to draw in tenants.
Wood is common in single-family homes and in apartment buildings of six stories or less but still fairly rate in commercial office buildings. The Ascent tower has already become the subject of some international interest.
City officials recently approved plans for the 21-story tower. Now, the project developers are tweaking plans to add two more floors, a change that would make the Ascent the second-tallest mass-timber building in the world, behind a 24-story timber tower in Vienna, Austria.
The project would add floors supported by timber atop a four-story concrete parking garage. Unlike buildings made of steel or concrete, the tower will be able to go up fairly quickly. Timber components beams can be fashioned and assembled off-site and installed in just months.
The work could begin as early as spring 2020 and wrap up in 2023. But the Milwaukee tower, for now, is an outlier.
For one, most mass-timber buildings are still being put up on the coasts, according to HGA structural engineer Lauren Piepho. Speaking at a U.S. Green Building Council event in Minneapolis this summer, Piepho said mass-timber buildings are “absolutely coming to the Midwest but (the trend) has been a little slow on the uptake. It’s definitely something coming down the line.”
The United States has 545 mass-timber projects that are either built, under construction or in a design phase, she said.
Environmental benefits
Wood, besides being a material capable of making a building distinct, sequesters carbon and provides environmental benefits that can last generations. What’s more, it usually takes relatively little time and energy to harvest wood and put up wood buildings.
Wood has 65 percent less weight than steel or concrete. Being lighter means that the foundations of wooden buildings don’t require a great deal of concrete to provide support, she said. Less weight also means less labor. A floor deck installation needs 25 percent fewer workers, she said.
Construction times can be reduced, too, by at least 25 percent. The developers of a Hillsboro, Oregon, credit union saved two to four months on construction, she said, and T3 went up in just 9½ weeks, much faster than comparable office buildings.
Wood allows builders to do more prefabrication than other materials, which reduces construction time. “That’s a huge benefit,” she added.
Also, wood tends to look attractive.
“It’s really an experience quite different than most other buildings,” said Carolyn Bates, vice president of Midwest Research for JLL, which leases T3. The building is “beautiful” and offers tenants “a brick and timber vibe” but with all new features.
T3 also has “brand new amenities,” she said. “It’s a differentiating product. When you’re marketing an office building it’s important to stand out, and T3 does that.”
One question that arises with mass timber buildings is whether they are as fire-resistant as other structures. Piepho said most wood projects use glue-laminated timber, cross-laminated timber, and nail-laminated timber. All have been tested extensively and all have strong fire-resistant qualities, she said. Mass timber chars on the outside, insulating the interior wood.
In the future, wood buildings are likely to reach only higher. The current limit on their height is set at 85 feet, according to the International Building Code. The number will increase to 18 stories in 2021. Taller buildings are coming, said Piepho.
– Frank Jossi of Finance & Commerce contributed to this article.
