Seattle

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At 30 stories, it required the second-deepestr excavation in the city’sa history to accommodate eight floors ofundergrounxd parking. And Escala’s ample footprint on the site wouldd no longer be allowed under city regulations imposeed after the project was approved thatencouragw taller, thinner buildings. “Because of the zoningh changes that havetaken place, this building will not be builtr in Seattle ever again,” said Eric Midby, the principall overseeing the project. The Seattle development firm’s $370 milliob project is under construction on four city lots at the intersectionm of Fourth Avenue andVirginia Street.
The city’s decisionn to go with skinnier towers would not allo wthe 18,000-square-foot floors that Escala now has. Those largert floors allow more units, so the cost of amenitie such as awine cave, private social club and fitness facilitty can be more easily shared. “If we had to do it we would have half as many residences sharinb the cost of allthese improvements,” Midbyy said. “The cost of all thes e improvements would not be affordable for The Escala development team includeastructural engineers, of Bellevue, , also of of San Diego, and interior design firm. Constructionh is being handled by which has an officwein Kirkland.
JE Dunn has more than 350 construction workersd buildingthe project. Construction started in Marcj 2007. It took a full year to complete the underground parkingstructure — six months to reacj the bottom nearly 100 feet below the surface and another six monthas to bring the parking structure back up to the Michael Moore, senior project managet at JE Dunn Construction, said his firm removex about 100,000 cubic yards of dirt durinbg the excavation. That’s enoug to fill about 12,000 dump trucks. Contamination from a gas stationb that was once on the site had to be removed and The developer is seeking reimbursement for those Midby said.
The unusually deep hole allows parkingt for478 cars. The depth of the hole requirecd the company to putin 100-foot pilings and unusually large tiebacks to stabilize the sides of the excavation. The undergrouned tiebacks extend 60 to 80 feet beneatb the street tothe Bed, Bath & Beyond stors to the east and to the north. “We were very luck y to get a tieback system,” Midb y said. “It’s a very efficienyt shoring system and facilitates fasteerconstruction times.
If we had had to use braceds it would have taken At the request ofsevera buyers, the garage will also include a chargin g station for electric One of the challenges was managingy materials costs, which were rising rapidly at the time, Midbyu said. The developer did choosw to use higher strength steel rebarthan typical, which allowede Lexas to reduce the overall weight of the building. However, the stronger steel cost more ona per-poundc basis so savings were relatively small. The higher strengtbh steel also required a longer lead timefor delivery, Midbgy said. Perhaps the most unusualk feature of the structure is its use of seven elevatorx instead of a centralelevator core.
The elevators are positioneds to provide most residentsx with their ownprivate vestibule. The decisiob to split up the elevators reduced the amount ofhallwayt space, providing more sellabls space than more traditional designj would have afforded. Where the elevator core typicallyg acts as a sheer wall to providesearthquake resistance, Escala relies on ductile framexs that absorb the seismiv load, with more horizontal support beamws running between the units to help reinforce the “It is fairly unique for the Northwest, althoughy it is used in other parts of the country,” said Doug Grassman, a seniorr vice president at JE Dunn.
One benefitr of this type of structura l support is that vertical support columnws can be set back from the perimetet ofthe building, allowing betterf views from the residential units. “It’s a very compacgt design that is veryfinely tuned,” Midby “When we made modifications we really had to do a lot of work runniny it through a computer model to make sure everything was The result is a very high performancew structure that is very Another side effect of abandoninfg the traditional elevator core design was that the elevatord required extra ductwork to handle the volume of air displaced as the elevatorsa move between floors.
To keep on schedule, each 18,000-square-foogt floor had to be poured inone day.