Presented with an untamed 10 acres of wooded chaparral and hypnotic views over San Francisco Bay, architect David Darling’s clients understood that anything built here must be subservient to the land. After the family, South African transplants, purchased the Sonoma property and its rammed earth residence, they asked Darling to develop a series of outdoor destinations on the south-facing slope below the house. In addition to a solar-heated pool and an outdoor kitchen/dining area, they wanted a hidden pavilion where they could meditate and exercise.

“The driving objective was to create a series of spaces tucked into the hill so you could see beyond them,” says Darling, principal of Aidlin Darling Design. In keeping with a strong conservation ethic, all the plantings are native or drought tolerant and minimally irrigated. Structures are built with natural or recycled materials and are passively heated, cooled, and cross-ventilated.

In a landscape writ large, the firm’s design merges natural and man-made, a keen vision that’s not lost on visitors. Low walls of board-formed concrete and stacked stone define paths that crisscross the slope between the house and the new saltwater pool, navigating native grasses and existing rock outcroppings. A few steps below, the dining area is composed of board-formed concrete columns, a gravel floor, and a ceiling of repurposed galvanized pipe. “The [now vine-covered] piping ages gracefully and has structural stiffness that allows for decent spans and cantilevers,” Darling says.

But the property’s inner sanctum is the spa pavilion. Half-hidden east of the pool in a grove of oaks, manzanitas, and madrones, it contains a yoga studio, steam room, changing rooms, bathroom, refreshment bar, sundeck, and outdoor shower. “You have to duck under branches to get to it,” he says. “We purposely left the path borderline treacherous to give you the sense of hiking to a hidden spot in the woods.” Two tall, curved earthen walls set up the entry sequence—a layering idea inspired by African bomas, or enclosures.

The pavilion consists of simple cedar boxes within a larger glass enclosure, its trellised-topped roof and cantilevered deck virtually disappearing into the trees. Retractable south and east walls extend the interior onto the deck and eliminate the need for air-conditioning.

Taking advantage of the slope, the design team stitched the pavilion to the land, getting it as close to the trees as possible. As a rule, the architects try to stay out of the drip line, but here they used some tricks to get closer. In addition to cantilevering the deck, “we drilled strategically located piers to avoid root structures, then we bridged from one to the other with a grade beam foundation wall,” Darling says. The grade beam, buried just below ground, allows roots to grow beneath it.

Building materials reinforce the resource-efficient theme. The pavilion is clad in reclaimed cedar fencing, whose natural tannins resist insects and water. Its floor is salvaged teak, and the trellis covering the roof is made from sticks of lodgepole pine. “It’s the skinniest part of the pine tree and considered a waste product,” Darling says. “The pieces are very straight but still have an organic appearance.”

All built components take advantage of the shade provided by trees while minimizing impact on fragile root systems. “We were asked to create spaces that served as an escape—an extension of the house,” Darling says. “But we were also were thinking of them as an extension of the landscape.”



Project Credits:


Project: Sonoma Spa Retreat, Sonoma, Calif.
Architect: Aidlin Darling Design, San Francisco
Contractor: Burlington Construction, Sonoma
Structural Engineer: Berkeley Structural Design, Berkeley, Calif.
Civil Engineer: Lescure Engineers, Santa Rosa, Calif
Landscape Contractor: Landmark Landscape Co., Santa Maria, Calif.


Resources:

Doors: Fleetwood Windows & Doors
Lighting: BK Lighting, Bega
Stains: Cabot Stains