Mass Timber, CLT, Milwaukee, Wisconsin, Office Building, Architecture
Scott Hilling/ENR, Thonrton Tomasetti, C.D. Smith
Fire officials accept the unprecedented use of the sustainable material in a 284-ft-tall wood and concrete frame
In January 2019, Preston Cole left his post as Commissioner of the Milwaukee Dept. of Neighborhood Services and became Secretary of Wisconsinâ€™s Dept. of Natural Resources. It was a step up for the 25-year veteran of public serviceâ€”a forester by professionâ€”who as the cityâ€™s top building official had reformed DNS by creating one-stop permit shopping and fostering a developer-friendly environment.
For the building team seeking his required signature on a variance for an unprecedented 284-ft-tall mass-timber and concrete high-rise, Coleâ€™s departure from DNS was both untimely and unsettling. â€śWe had a scare when Commissioner Cole got a new job,â€ť says Jason Korb, principal architect for the local firm Korb + Associates Architects, which is designing the 25-story code outlier, named Ascent.
In May 2018, with Korbâ€™s initial concept for a 19-story mass timber apartment building in hand, the Ascent team approached Cole to feel him out about the project, which would break the cityâ€™s 85-ft height limit for wood. â€śIf he wasnâ€™t into it, no way would we go forward,â€ť says Korb.
A Milwaukee booster, Cole was all for a showcase for tall mass timber in the forest product stateâ€™s biggest city. â€śI liked their energy,â€ť Cole says of the Ascent team.
Green Building Material
He was so enthusiastic about the innovative use of the green building material that in July 2018 he directed the DNS commercial-building code variance committee to find a way to get the tall building, with its combustible wood frame, â€śacross the finish lineâ€ť without compromising public safety.
In January 2019, the Ascent team had no way to know, but Coleâ€™s departure would not throw a wrench in the works. Erica R. Roberts, Coleâ€™s successor as commissioner, also was excited about tall-timber innovation.
On July 24, two long years after the Ascent team first presented the concept to the DNS advisory committee, Roberts granted the variance for the buildingâ€”which had grown to 25 stories and 488,800 sq ft. The protracted approval time was necessary to thoroughly investigate the project, says Roberts. â€śI hope the steps taken by Milwaukee can be used by othersâ€ť to reduce approval time, she says.
Construction began in September. If finished as planned on July 1, 2022, Ascent will break height and size records both for pure timber and composite timber and concrete structures anywhere. Though only by 4 ft, the building will exceed the height of the worldâ€™s tallest wood buildingâ€”MjĂ¸stĂĄrnet, a 122,000-sq-ft mixed-use building in Brumunddal, Norway, completed in March 2019.
Coleâ€™s departure had added more uncertainty to an already risky but attractive development due to woodâ€™s appeal and renewability. The U.S. has only one 85-ft-tall wood building, Carbon 12 in Portland, Ore., completed in 2018, and no modern wood building taller than 85 ftâ€”the historical height limit for a structure made from a combustible material. The restriction is in great part due to concerns about fire fightersâ€™ vulnerability in a blaze.
No U.S. Precedents for Grand-Scale Timber
There was no permitting path for a timber building that would exceed the height limit by nearly 200 ft. There were also no U.S. precedents for grand-scale â€śsupertallâ€ť timber and concrete building development, financing, insurance, design, detailing, material procurement, fabrication and construction.
The 19 floors of wood-framed residential space, which will sit on a six-story structural concrete parking podium, will contain just over 80,000 cu ft of glue-laminated timber fabricated into 1,150 glulam columns in 17 different sizes and 1,320 glulam beams in 50 sizes with 36 different lengths. Ascent also will contain 336,000 sq ft of cross-laminated timber (CLT).
Thatâ€™s a tall order, especially as, initially, no one on the Ascent team had any in-depth experience with mass timber, let alone supertall mass timber. â€śHad we known all the challenges, we probably wouldnâ€™t have startedâ€ť the journey, says Tim Gokhman, managing director for Ascentâ€™s local co-developer, New Land Enterprises, which is in partnership with Wiechmann Enterprises.
Tim and his father Boris, who co-founded New Land in 1993 with fellow Ukrainian immigrant Walter Shuk, were no strangers to uncharted waters. They had escaped the Soviet Union, which controlled Ukrain