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Credit: Ethan Kaplan

San Francisco boasts many unique attractions, and among the offerings at Golden Gate National Recreation Area is House of Air, a trampoline facility in a former biplane hangar on the historic Crissy Field in the Presidio. The facility, which opened in September 2010, houses performance trampolines where athletes can practice snowboarding and other extreme-sport moves. There also is a trampoline dedicated to an ongoing game of dodge ball, trampolines for classes and jumping, and a bounce house for children.

House of Air sits next to a biking and walking path with views of San Francisco Bay. It’s a location that came at a cost. This former military hangar was built in the 1920s when materials such as asbestos and lead were commonly used. The cleanup effort was significant, but one that Mark Horton, FAIA, principal of San Francisco–based Mark Horton / Architecture, took on with enthusiasm.

Most of the project’s budget was dedicated to updating seismic requirements and cleaning up the toxic site. The process took close to eight weeks. This already complex undertaking was further complicated by the fact that the Presidio and its structures are historic buildings on federal property, which mandated that Horton go through an approval process with the Presidio and required that he keep many elements of the building intact. The exterior was clad in a corrugated cementitious material, which is still made today. However, while today it is cement-based, 50 years ago it was asbestos-based and, under the Presidio’s historic regulations, the material had to stay in place. “That meant that anytime you put a single screw hole through it, you needed to tent it because you’re going through toxic material,” Horton says. “That was a huge amount of work.” Tenting also was necessary when replacing the window panes. “The window caulk holding the panes in place was asbestos-based,” Horton says. “Taking each one of those panes out was toxic remediation.”

The light-frame steel building has a 6-inch-thick concrete roof, which was bombproof when it was built (but would not withstand modern bombs). The architects were required to keep the roof for historical reasons. To obey seismic zone requirements, structural steel members were added inside the building to support the roof’s weight. Each member added was going into an area that was coated in lead paint, so the lead paint first had to be removed. The concrete floor of the hangar also had endured years of aviation fluid spills. “We had to spend a lot of time cleaning that and resealing it,” Horton recalls. “Almost every single surface in the building was, by some standard, not eco-friendly.”

The House of Air is now LEED Certified and the end result has been especially gratifying for Horton. “We started where the client had no idea that architecture could make a difference or be an important aspect of their project,” he says. “What is most rewarding for me is making architecture out of a project that didn’t start out that way.”