Wave-like composite facade animates SFMOMA expansion.
While visually interesting, the primary facade of the SFMOMA expansion (Snøhetta with associate architect EHDD) was not originally designed to pioneer a new material system. All that changed when William Kreysler visited the architect’s New York office. “I went there to meet them about the interior,” recalled Kreysler, whose firm—composite specialists Kreysler & Associates—had been called in to advise on the project’s vaulted ceilings. “I asked about the exterior, how that was going to get done. They didn’t know.” Over the coming months, Kreysler & Associates transitioned from interior consultant to envelope fabricator as the facade itself was transformed from a ductal concrete fantasy to a fiber-reinforced polymer (FRP) reality. Along the way, thanks to a patent-pending process developed by Kreysler & Associates, the design and fabrication team positioned itself on the cutting edge of high performance building enclosures with the first major use of FRP cladding on a multi-story facade in North America.
When a client’s representative called to ask if his firm—at that point poised to collaborate with an outside glass fiber reinforced concrete (GFRC) contractor on mold-making—would consider taking on fabrication themselves, Kreysler’s reaction was mixed. “I said, ‘Yes, I don’t see anything particularly complicated about it in terms of fabrication,'” he recalled. “The problem was the fire codes. No one in the [FRP] business had attempted to pass the fire code requirements.” Kreysler & Associates had been keeping abreast of the regulatory situation, and had been involved in inserting a new section for FRP into the International Building Code[s]. But the fire code test itself, NFPA 285, is expensive. After further conversation, the client committed to partially fund the test. “We got to the point where I said, ‘Okay, I’m willing to put some money at risk here,'” said Kreysler. “We went ahead and did it.”
Kreysler & Associates’ system, which they call Fireshield 285, passed the test, likely becoming the first FRP cladding panel to do so. Having thus paved the way for a more widespread application of the lightweight material to building exteriors, the fabricator’s next step was to bid to three facade companies. Of the firms to which they introduced their design, Enclos was the most engaged. By the end of the first meeting, Kreysler & Associates and Enclos had brainstormed ideas to eliminate the secondary structural frame intended to go in front of the weatherproof wall specified in the original design.
Soon the group introduced an additional innovation. Enclos is known for its expertise in unitized panel systems rather than conventional walls, explained Kreysler. “We said, ‘Maybe we could make our material so lightweight, we could just fasten our material onto the front of the unitized wall panel.'” Kreysler is quick to give credit to Enclos “for seeing the potential and sharing their expertise in building facades so we could work collaboratively to take full advantage of both systems’ strengths.” With a combined composite-unitized wall panel assembly, one team of contractors could erect the entire rain screen in a single shot. “It would save one million pounds of structural steel, plus the time of going around the building three times,” said Kreysler. Not surprisingly, “the contractor liked it, and the owner liked it,” he recalled.
Only one obstacle remained. “Unitized wall systems are designed to go in straight lines, or if curved, are curved in a radius,” said Kreysler. “But if you look at the facade of SFMOMA, it’s all over the place.” The Kreysler & Associates-Enclos team quickly developed a solution: Kreysler & Associates would fabricate their panels with edges of different depths to bridge the gap between the facade’s surface and the flat unitized panel wall. “We were able to create a curved front even though the the wall behind was a nice straight line,” explained Kreysler. “From the front of the building you don’t see any of the edges—you see this flowing curved line. That was a big breakthrough, and as a result, Enclos really got behind our system.” The client was suitably impressed, and Kreysler & Associates won the contract against bids involving GFRC systems. “Even if our price turned out to be higher, the benefits of only going around the building one time, and the benefits of a system considered to be a higher-quality weatherproof wall” won out, said Kreysler.
Though the expansion is not expected to open until 2016, Kreysler & Associates’ work on the project is finished. The installation went “beautifully,” said Kreysler. The 710 unique FRP panels were mechanically fastened and bonded to the unitized wall using a custom aluminum extrusion. The Enclos representatives had been nervous, he recalled. However, “the project manager told me that in the years he’s being doing this, it was the most complicated project he’s ever done, but in the end this was the most straightforward part of the project.” As for Kreysler himself, he has no regrets—quite the opposite. “It was tricky, but it was fun and interesting,” he said. “And it was nice to know that we were breaking new ground.”