Green Roof and Streetscape at Fifth Avenue North

Timothy Hursley

Sellen

Green Roof and Streetscape at Fifth Avenue North

Seattle Center, the historic campus of the 1962 World’s Fair, is now a regional visitor attraction hosting a variety of large-scale events and festivals throughout the year. Until the summer of 2008 most visitors parked in surface parking lots, the largest of which was 12 acres. In 2005 the Bill and Melinda Gates Foundation purchased this lot as the site for their campus. As part of the sale, the Foundation agreed to replace the surface parking with a new parking garage. The resulting project consolidated the number of parking spaces held on 12 acres of asphalt into an underground parking garage that has a surface area of only two acres. A 60,000 square foot extensive green roof covers the building’s roof.

The green roof was designed to be a fifth façade to the building. The new building lies in a low spot that is visible from the surrounding hilly neighborhoods and the Space Needle. Historically, the site has always been a clearing amongst the surrounding landscape and the city. Well before it was a paved city parking lot, it was a natural meadow clearing. The low, dense planting of the green roof maintains this historic sense of an open, green landscape on the site.

With a goal of being low-maintenance and aesthetically pleasing, a mix of drought-tolerant sedums and sempervivums were planted on the roof. The low profile of the build-up on the roof slows down and absorbs the rainwater that hits the roof, reducing the amount of stormwater run-off that leaves the surface of the roof.

Details

Location: Seattle, WA
Size: 1.5 acres
Client: Bill & Melinda Gates Foundation, Seattle Center
Completion Date: 2008

Project Team

NBBJ, Architect
KPFF, Seattle, Civil Engineer
GGN, Landscape Architect
ARUP Seattle, Structural/Mechanical/Electrical Engineer
Sellen, General Contractor