Ascent, a 25-storey mixed-use luxury development in Milwaukee, USA has been officially certified by the Council on Tall Buildings and Urban Habitat (CTBUH) as the world’s tallest mass timber building.

Standing 284 feet tall, Ascent, located at 700 E. Kilbourn Avenue in Milwaukee’s East Town neighbourhood, was also designated as the tallest concrete-timber hybrid building with the podium containing the first five storeys rising on concrete. The title for the world’s tallest mass timber structure was previously held by the 280-feet Mjøstårnet building in Brumunddal, Norway.

Designed by Korb + Associates Architects for the developers, New Land Enterprises LLP and Wiechmann Enterprises, Ascent redefines luxury living, featuring retail and parking in the first five storeys, a pool on the sixth floor, 259 residential apartments, and an impressive 25th-floor community space with two terraces, two entertaining kitchens, an outdoor cinema, a residents-only staffed bar, fireplaces, a game room, semi-private workspaces and more. Amenities also include a sauna, an indoor/outdoor fitness centre, an indoor dog agility centre, a doggie spa, electric car charging stations, and bike storage.

Thornton Tomasetti, which provided structural design services to Korb & Associates Architects for the building, also led the mass timber design program, including providing inspections of the mass timber system and worked with the USDA's Forest Products Laboratory to complete the world's first three-hour column fire testing program for glulam columns.

According to Thornton Tomasetti, the mass timber residential floors are constructed above five levels of concrete parking garage. A system of glue laminated timber (glulam) beams and columns support cross-laminated timber (CLT) floors. Two concrete cores provide lateral stability. The design exposes the mass timber construction wherever possible to display its natural qualities. Fire testing proved that the timber structural members meet or exceed fire rating code requirements.

“An efficient system of post-tensioned concrete beams transfer loads from the timber residential floors to the concrete garage structure below. The superstructure is supported on concrete-filled steel pipe piles – the highest capacity piles yet built in Wisconsin. This system minimises material quantities and reduces installation time, for substantial cost savings,” Thornton Tomasetti explained.

C.D. Smith Construction, the general contractor overseeing mass timber construction at Ascent, stated that the use of mass timber for the structural system decreased construction time by approximately 25 percent. Ascent was built using a digital ‘twin’ model, so every beam, column and panel could arrive on site ready to assemble, with holes predrilled to within 1/16 inch accuracy. The timber for Ascent’s structure was sustainably sourced from Austria.

“This is history in the making,” says Justin Smith, president & CEO, C.D. Smith Construction. “All stakeholders have contributed to this momentous moment. Despite a global pandemic, this team has achieved construction milestones and delivered on promises made more than two years ago. Congratulations to all involved!”

CEO of New Land Enterprises, Tim Gokhman, whose firm co-developed Ascent with partner Wiechmann Enterprises, said: “We didn’t set out to break records. We just wanted to create the best experience within the built environment for our residents. Mass timber is faster, more precise, lighter, more sustainable, more beautiful, and supports our commitment to biophilic design.”

“This building sequesters enough CO2 that it’s the equivalent of taking 2,400 cars off the road for a year,” said architect Jason Korb, whose firm designed the mass timber structure.

Breaking ground in August 2020, after approximately two years of research, testing, planning and collaboration with external stakeholders, the Ascent development brought together experts from around the world and established a model for tall timber that may help pave the way for future projects.

Ascent welcomed its first residents on 15 July 2022.

Images: Korb + Associates Architects