The 44-million-pound roof is being preserved and fortified for the new arena, which is doubling in size to accommodate bigger events, including hockey and basketball.
The 44-million-pound roof is being preserved and fortified for the new arena, which is doubling in size to accommodate bigger events, including hockey and basketball.

Construction crews began pouring concrete for the first of many columns under the iconic Seattle Center arena roof. While 2019 was about digging down, 2020 is about building the arena back up, said Ken Johnson, executive vice president of construction at Oak View Group.

The developer behind the $930 million rebuild of the arena invited media to tour the site on Tuesday, Jan. 21. An October media tour showcased the raising of the original roof from 1962 on supports while crews began excavating the bowl of the new arena.

Johnson said crews, led by general contractor Mortenson Construction, are removing 600,000 cubic yards of dirt from the site to double the arena’s original size. About three-fourths of the excavation has been completed, he said, with the rest expected to finish in February. The new arena bowl will be 53 feet below ground.

The 44-million-pound roof, designed by architect Paul Thiry for the Seattle World’s Fair, is being supported by 72 temporary steel columns and two “kickstands,” or spliced together steel reinforcement structures on the exterior, said Mortenson project executive Greg Huber.

“You’re never going to see something like this again,” Huber said of the engineering that went into supporting the massive roof.

The Seattle Landmarks Preservation Board required the roof and the arena’s original windows to be preserved. Johnson said the windows are catalogued and in a Kent storage facility.

Scaffolding has been erected under the roof, where crews are ensuring it will be able to support various equipment.

“It’s our one chance to check under the roof,” Johnson said, “so we’re making sure we do it right.”

While Jan. 21 marked the first concrete pour for the project, the total rebuild will include 37,000 yards of concrete for columns, slabs and footings, which is roughly 3,700 truck loads, Huber said.

Johnson said the project remains on schedule to finish in summer 2021.

One benefit of preserving the roof has been the cover it provides from the rain and other elements, Huber said. It also limits the cranes and other equipment that has to work around the temporary supports.

“This probably takes the cake in terms of times we’ve had to be creative with our pile-driving work,” Huber said.

As crews work back up from the bowl, the arena’s 20 permanent “Y” columns and four buttresses will be reconnected, the columns extending down to the base of the structure.

“How we build up and take things out is a very important part of how we do things in the next 6-8 months,” Johnson said.

Horizontal boring continues south of the Pottery Northwest building as an access tunnel is being worked on that will be used by delivery trucks to reach the arena’s loading dock. Huber said there will not be public parking under the arena.

When completed, the Seattle Center arena will provide more than 18,000 seats for concerts and basketball games. Huber said seating is scheduled for delivery in spring 2021.

The summer 2021 opening will be ahead of the start of hockey season for Seattle's new NHL team, which does not yet have a name. The arena also does not have new naming rights yet, and the KeyArena signage remains on top of the historic roof in the meantime.