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Structural Integrity


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On Site
Structural Integrity
A Northern California House Shows Its Green Roots.

here are a lot of people out there who can credibly call themselves green builders, but we don't know any custom builder who lives and breathes the green way more than David Warner. Working with some of the country's top residential architects, Warner's San Rafael, Calif., company, Redhorse Constructors, has made a specialty of building houses that match cutting-edge sustainability with architectural zing. Warner himself is a veritable one-man clearinghouse of information on green products, technology, and construction practice. So when he built a new house for his own family, it was sure to be stylish, sustainable, and a showpiece for his company's work. The result is all that, to be sure, but it's also an object lesson in the rewards of simplicity, sensitivity to the natural world, and knowing when to say “enough.”

Fittingly, the project began with a special piece of land. Warner and his wife, Suzanne, “weren't really looking,” he says, but this site spoke to them. In the steep hills that rise above their hometown of Fairfax, Calif., its 55 acres comprise patches of meadow interspersed with redwood and Madrone forest. The latter was especially appealing. “Madrone forest—especially a healthy one—is very rare around here,” Warner says. And, as it turned out, they already knew the place. “It happened to be on one of our nice hiking loops. I didn't know it was private land; we had always thought it was public land.”

In buying the property, the Warners actually made it more public than it had been. “The zoning allowed for 14 homes,” Warner says, “and we only built one, and we retired the development rights.” In exchange for a “private open space” easement, the Warners got a tax write-off, plenty of elbowroom, and the ability to ensure that this special spot would get kid-glove treatment—a fundamental premise of every Redhorse project. One of Warner's first moves was to identify an existing roadbed on the property, long disused and overgrown, that had been made in the early 1900s to build a municipal water tank. Warner used the path of the road for the driveway and the footprint of the house, minimizing site disturbance.

In designing the house itself, architect Ken Kao helped the Warners collect their ideas, which centered on a sense of shelter they had experienced many times, but seldom at home. “Tuolumne Meadows in Yosemite [National Park] is one of our favorite places to go,” Warner says, “and we always liked the idea of cabins.” Kao responded with a plan that distributes living spaces among three closely clustered but physically separate pavilions. The first holds a guest suite and sheltered parking; the second, the kitchen, dining, and living areas; the third, a master suite. (Out of sight, atop an adjacent knoll, Kao placed a swimming pool and pool house.)

“My friends always say, ‘You're crazy; you have to go outside,'” Warner says. But this “village” floor plan offers distinct advantages over clustering rooms under a single roof. More surface area gives each space greater exposure to sun, views, and natural ventilation. The arrangement also makes living volume scalable. “When the buildings aren't occupied,” Warner says, “they're basically dormant.” But the conditioned space can expand almost instantly to accommodate the Warners' grown children or out-of-town guests. The result is efficiency, flexibility, privacy, and the cabinlike feeling the Warners like so much. “In some ways, the floor plan is more convenient than it was in our more conventional house,” says Warner, whose bedroom is steps from his kitchen. “You just go outside as part of that distance. It's fun, too, because you get to experience the outdoors.”

The structures deploy a short list of exterior materials—concrete, wide redwood siding boards, and Douglas fir-framed sliding doors—in broad, simple planes. A flat roof edged in black steel tops off the composition, its deep overhangs shading south-facing glass and sheltering outdoor walkways. The interiors follow suit, with concrete and bamboo floors, bamboo wall paneling and cabinetry, gypsum board ceilings, and not much else. “We stripped layers off the structure, which is conducive to modernism,” Warner says. But the natural materials temper Kao's austere geometry and detailing. “Ken's work is very modern, but it can accept these more organic surfaces.”

Warner's green ethic is evident throughout. The concrete that comprises the bulk of the buildings' structure contains a high proportion of flyash as a replacement for energy-hogging Portland cement (see “Cool Mix,” next page). The fir framing lumber was resawn from the rafters of an old church that Warner's company rehabbed. The steel came from a reclaimed materials supplier. The custom windows and doors are FSC-certified Douglas fir. The wide redwood siding was sawn from reclaimed logs, which were buried in the forest a century ago because they were too large for the milling equipment in use at the time. The steps to the pool house are salvaged stone from San Francisco curb cuts. “And we've got the net-zero thing going,” Warner adds, noting the bank of ground-mounted photovoltaic panels. “They back-feed into the grid.” Sunlight provides a share of the space heating by warming the slab floors. Warner opted for a gas furnace/fan coil system rather than in-floor radiant heat, however, due to the time lag involved in bringing radiant slabs up to temperature. In pavilions meant to be used on a moment's notice, “you don't want any delays,” he says.

Given Warner's enthusiasm for new ways of building, the house was bound to be a test-bed for his company's future projects. “We have solar hot water systems for the pool,” says Warner, who was willing to sacrifice year-round use for fuel efficiency. “We kept it very shallow; it's a lap pool. It stays in the 80s even into November, and if we get a series of warm days in December it will heat up—all without fossil fuels.” A saltwater treatment system keeps the pool clear without adding chlorine. The project gave Warner a chance to experiment with a soy-based gypsum board from a small California manufacturer. “I did two rooms in it, to make sure it worked,” he says. He also seized the opportunity to indulge a bias toward simplicity. “I didn't go with [electrical] control systems,” some of which draw current even when the lights are off. Instead of interior window shades, he devised an exterior drape that hangs from a track recessed into the roof soffits. “You just move it to where the sun is,” he says. The landscaping employs low-maintenance native species, and now that the plantings are established, “I'm watering the plants once a week for five minutes on a drip.”

Warner knows his house wouldn't suit everyone. “It's not going to work for the guy who wants a library paneled in walnut—no way,” he says. But he's not hiding it either. “I'm bringing clients up here now,” he says, and it has opened some eyes. “When people come to our house, they ask questions.” Among them: What's it like to walk outdoors between rooms? To live in such simple spaces? To mow the lawn only when it reaches knee height?

“They ask questions, and by asking the questions, they're in the zone.” That zone, he adds, is where it all comes together: “From land use policy to how you build the house,” to how you live in it, and to how all of these things reflect your values. “It's all one,” he says.
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