Virtual tour of Ascent tower shows promise of mass timber

Builidng a high-rise tower with timber isn’t quite like using steel or concrete. Milwaukee’s 25-story Ascent Tower, the largest such project in the world to use mass timber instead of standard construction methods, is showing the industry why.

Finding an insurer for the unconventional building, on which ground was broken in August 2020, proved difficulty. Also hard was showing building officials that the new construction material would be safe for a high-rise apartment tower.

In the end, though, it took a relatively small construction team significantly less time to build the tower than a bigger team would need for a more conventional project. And the use of mass timber rather than steel or concrete demonstrated an effective method of lowering a new project’s carbon footprint.

“It’s a fact that real estate — both construction and operation — is a humongous contributor to the CO2 footprint in the United States, about 40%,” said Tim Gokhman, managing director for New Land Enterprises, the developer of the Ascent tower. “We absolutely need to change the way that we build buildings and operate them.”

Gokhman and officials in the Ascent’s design and construction team joined the Washington-based nonprofit Woodworks on Wednesday to discuss how the project came together and how other developers might do something similar.

Crews overseen by C.D. Smith Construction topped off the 284-foot tower last month and are working to have the entire project completed by this summer. The building relies on a six-story concrete parking structure to support a 19-story structure built with mass timber, a material made of wood that has been pressed together.

Jason Korb, principal at Milwaukee’s Korb + Associates Architects, said the project team worked with Milwaukee’s Department of Neighborhood Services early in the planning phase to obtain the various code variances needed to ensure the project could proceed. Thornton Tomasetti also served as the project’s structural engineer.

Although previous research had strongly suggested that building such a structure with mass timber would be possible, the project team was nonetheless eager to verify the new construction method would hold up in the real world, Korb said. The team therefore performed tests at the U.S. Department of Agriculture’s Forest Products Laboratory in Madison to evaluate how the timber beams and columns and the laminate that holds them together  — would stand up, say, in a fire.

“The key is to engage code officials immediately,” Korb said. “If the code officials don’t buy it, then you don’t have a project.”

The tower’s project team also met to plan for the construction of the Ascent, said Chris Johansen, a project manager at C.D. Smith. Contractors held a series of 60 weekly meetings, each lasting from three to four hours, to plan for every step of the project.

The timber tower required different construction techniques than a typical concrete apartment building. C.D. Smith, for example, employed about a dozen workers in the installation of each of the tower’s floors. A typical concrete building, in contrast, would require 50 or so workers, Johansen said.

The smaller crew also completed each floor in about five to six days. On most projects, crews need from 8 to 10 days for a floor, Johansen said.

The work on the mass-timber project also produced less waste. Each of the Ascent tower’s beams or columns was labeled independently and designated for a specific part of the project.

“Everything on the job has a specific place that it needs to go,” Johansen said. “There’s not really any one column or beam that’s replaceable.”

Construction crews took great care to keep moisture from staining the wood components, Johansen said. Every floor was equipped with a sump pump into which workers would use leaf blowers to move water within 24 hours of a rain storm.

“Everyone is on-board and aiming for the same goal: turning this thing in hopefully ahead of time and on budget,” Johansen said. Follow @natebeck9