44-million Pound Floating Roof a Massive Undertaking

By Karen L. Edwards, RCS Editor.

The roof will sit atop the new Seattle Center which will be home to the city’s new NHL team.

Called an engineering marvel by Seattle’s K5 News, the 44-million-pound roof was lifted up by 72 temporary steel columns so that workers could excavate tens of thousands of yards of dirt and construct the new arena.

K5’s Chris Daniels got a sneak peek at the site in January when the site was opened for a brief media tour. At the time of his visit, crews had “removed nearly 75% of the needed dirt to build a new bowl 53 feet below ground, doubling the size of the old Arena,” writes Daniels.

The Seattle Center construction is being done on the site of the old Key Arena and its iconic, 44-million-pound roof is being reused for the new arena; the reason why workers needed to dig down so far to build out the new arena. Jill Crary, redevelopment director at Seattle Center, told KUOW that the roof is worth preserving. "I like how it hugs the ground and how modest it is. A lot of these big arenas — they’re huge," Crary told KUOW’s Joshua McNichols.

It was a pretty impressive operation according to Mortenson Construction, the general contractor on the project. Greg Huber, Mortenson’s Project Executive told Daniels, “It is the result of thousands of hours of engineering. There hasn’t been anything quite like this.”

Construction has continued amid the coronavirus pandemic and Mortensen was able to lift the roof onto the temporary steel columns, cross beams and onto a temporary steel structure. Bisnow Seattle reports that “though heavy, the suspended roof is considered safe and is covered with sensors.”

The sensors are designed to detect winds and seismic movement with the roof and supports being designed to meet the guidelines of the American Society of Civil Engineers for withstand winds and earthquakes.  

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Image courtesy of Mortenson Construction.