A Concrete Guesthouse Commands a Ridge in Northern California’s Wine Country

A string of concrete-and-glass guest suites hugs the terrain in Sonoma, California.

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"The distinct, compact volumes are twisted or angled so they point out toward the view and away from each other," says Casper Mork-Ulnes of Mork Ulnes Architects, describing the three concrete-and-glass suites that comprise his minimalist design for an 840-square-foot guesthouse in Sonoma, California.

The clients wanted something low-maintenance and fire-resistant, making concrete a logical choice of material. "We also wanted a material with monolithic qualities that would appear grounded in the rocky landscape," says Mork-Ulnes. Its board-formed texture, created from standard lumber, lends warmth and "gives the guesthouse a domestic feeling and evokes the traditional wood siding often found on vernacular barns in the region." The northern and eastern facades, by contrast, are entirely glazed.

The 840-square-foot guesthouse Mork Ulnes Architects designed in Sonoma, California, comprises three concrete-and-glass volumes that line a great ridge.

Each suite of the guesthouse contains a master bedroom, a bath, and a deck that cantilevers above the downward slope of the ridge and the adjacent valley. Three pine entry doors punctuate the concrete-and-glass exteriors, adding more warmth and texture. To create continuity, Mork-Ulnes also wrapped the interiors in concrete and glass. "This keeps things elemental and pared down to allow the natural landscape to be the focus," he says. For a softer aesthetic, the interior concrete was formed with large panels instead of wood boards for a smooth finish that contrasts with the exterior’s character.

Sunlight pours through glass walls and washes over the interior's smooth, poured-in-place concrete walls, floors, and ceiling.

Glass walls and a concrete deck connect the guesthouse to Sonoma’s lush landscape.

The architects outfitted the baths with smooth concrete floors, walls, ceilings—and a cantilevered vanity.

The showers, too, are crafted from smooth, poured-in-place concrete.

The guest suites are marked by the three sloping, concrete roofs that seem to almost lift off from the walls. "The oblique ridges direct views from within the house out to the beautiful hills beyond," Mork-Ulnes says. "They also shade the windows, giving protection from the intensity of the summer sun."

The oblique concrete roofs for each of the guest suites angle upward to allow for expansive views of the rolling hills and the valley.

In siting the three-suite guesthouse, Mork-Ulnes carefully considered the landscape and its topography—the volumes nestle into or hug the natural contours of the ridge. "The three volumes step down with the grade progressively," he explains. "The roofs also step with the grade to minimize the scale of the building and allow the volumes to each have their own reading. This multi-gabled roof also helps to join the discrete units into a coherent whole, while its peaks and valleys echo the hillside beyond."

The three guest suites connect and appear as a massive minimalist sculpture set in the landscape.

Mork Ulnes Architects sited the guesthouse on the ridge in order to preserve the pool deck and flat portion of the property.

Artful the guesthouse is, the landscape around it takes the spotlight—just as Mork-Ulnes intended. "The building is located in the quintessential Sonoma landscape of golden, rolling hills and rows of grapevines in the valley floor below," he says. "The volumes sit among manzanitas on a fir-and-pine-forested hillside with views to more hills beyond—it was important to work with the land instead of against it."