To hear her preach the prefab gospel, building a home from scratch, on-site—with what she calls "sticks"—makes little sense, while a factory committed to punching out Glidehouses provides nothing but advantages. There is quality control and little waste. Because the house moves down an assembly line, shuttled from station to station with overhead cranes and constructed on a grid with precision cuts, the joinery is plumb, the angles true.
"The factory reuses; the stick builder throws trash in the dumpster. With prefab, you build only what is needed," says Kaufmann. "The wood and other materials are not exposed to rain and the elements. There is also the human element: you know people are going to show up for work. There's no waiting for the subcontractor."
To prove the idea's benefits, Kaufmann performed an experiment in 2003 and 2004. While Cullen built the Glidehouse prototype from scratch on their Marin County lot, she worked with a manufacturer to complete an identical Glidehouse in a factory. The results: the site-built Glidehouse took 21 months to design, engineer and permit, and 14 months to build. The modular version was built in four months. (Kaufmann thinks she can shave this down to six weeks or less.) The site-built home cost $363,950 to build, or $233 per square foot, while the modular house cost $290,500, or $182 per square foot, including shipping. Both required additional spending for lots, foundations, landscaping, driveways, decks and garages.
After the experiment, Kaufmann dedicated her firm exclusively to prefab construction. "I was just young and naive enough not to know how hard this would be," she says.
Kaufmann soon learned that there were established companies already manufacturing modular structures for oil-field workers or temporary classrooms—decent boxes for temporary shelter, though hardly Glidehouses, with their lightweight paperstone kitchen countertops made of recycled paper, their roofs ready for clip-on solar panels and their clerestory windows. But her efforts to reach them were unavailing—she would discover that they wouldn't even call her back because they considered architects too difficult, and too time-consuming, to work with.
Undeterred, she says, "I basically became a stalker" and got through to a few manufacturers, enough to persuade them that "the future can be much more than what they had been doing." She contracted with them to make 11 Glidehouses and one Breezehouse, but she was still frustrated by the length of time the revolution was taking. So in 2006, she took the plunge and bought her own factory, 25,000 square feet east of Seattle, from a retiring modular house builder. She moved in this past October, with a goal of producing 10,000 prefabs over the next ten years. That's close to the number of post-and-beam houses—still considered jewels of mid-century modernism—that Joseph Eichler built in California between 1949 and 1974.
For Kaufmann, prefab offers something else worth celebrating: a truly green building. "We've already done all the homework to find the most sustainable materials," she says. A client may like a bathroom to be blue or green, but either way it will be lined with recycled glass tiles, finished with nontoxic paint, lit by energy-efficient fluorescent bulbs and equipped with low-flow faucets and a tankless water heater.
"I think about the house like I think about a hybrid car," says Kaufmann, who drives a Toyota Prius. "You can be more efficient, but you don't have to change your life. With the hybrid, you still go to the gas station and fill it up. With the prefab houses, you make it easier to go green."
Her most cherished insight? "You have to stop thinking like an architect and start thinking like a manufacturer," Kaufmann says. "When I started on this, I didn't realize that the way to do it was to do it all."
William Booth is a Los Angeles-based staff writer for the Washington Post who covers culture and the arts.