Compounding the complexity of the envelope, the building required additional structural bracing to meet seismic load requirements; the site is located in a liquefaction zone adjacent to a major fault line. The construction team had to carve channels through the SIPs on site to thread steel beams throughout the structure.
“That was a coordination issue,” Ackerman says. “If we had been more aware of how SIPs worked, that coordination would have fallen in our lap before it became a problem on site. SIPs were still an excellent choice, given the client’s goals; it just takes understanding the product and what its limitations are.”
Finn Hill Middle School
In Kirkland, Wash., the Lake Washington School District wanted to replace Finn Hill Junior High School’s multibuilding facility with one single-story building that would become Finn Hill Middle School. The district challenged Seattle-based Mahlum Architects to deliver a new 116,000-square-foot facility capable of accommodating 750 students on the same site as the existing facility.
Logistically, construction on the new facility would have to wait until after the old school was demolished. Then the project would have about one year for its construction. The district also wanted the new school to further its goal of becoming the most energy-efficient school district in the state. These goals led Mahlum to specify SIPs.
To optimize construction efficiency, Mahlum based its design on a 16-foot SIP module, a height that the panels can span without requiring additional structural bracing. The one exception was the school gym’s high ceilings, which called for additional metal-stud support embedded in the walls.
The 16-foot module also created a uniform approach to sizing the classrooms. “One of the cool things about the SIP design process is that you get shop drawings for whole building,” says Anjali Grant, AIA, Mahlum’s project architect. “It all comes out numbered and panelized. You can see the entire building laid out and see how it will arrive on site.”
Given the Pacific Northwest’s wet climate, water intrusion was a major concern. “If there is moisture, you don’t want it trapped at the sheathing plane,” Grant says. “Rainscreens and air barriers are appropriate when cladding this system.” Mahlum specified a fluid-applied-membrane air-barrier system clad with painted fiber cement board and concrete masonry units.
Finn Hill’s tight envelope helped the school strive to be 47 percent more energy efficient than targets set by the U.S. Department of Energy’s Energy Star program; the school is now in the commissioning phase. The facility is also set up to be net-zero energy; currently, it is outfitted with 1,452 photovoltaic panels that generate 42 percent of the school’s energy needs. The facility has a south-facing roof area that can accommodate more panels to generate the balance of the school’s electrical consumption in the future.