San Francisco-based Spiegel Aihara Workshop (SAW) has completed the transformative architectural and landscape design of a 1962 home in Mill Valley for a couple and their two young children. The project, known as The Middle Half, dramatically reconfigures the home’s core to create an open, light-flooded interior and direct connection to the landscape. Raw, textured materials like galvanized steel, rough-sawn cedar siding, and cast-in-place concrete define the project and accentuate its unexpected, layered geometries.
“Often when thinking about preserving a thing—a structure, an object, a landscape, a city—one talks about preserving its ‘heart’ or its ‘core,’” says SAW co-principal Dan Spiegel. “But in this case, it was the opposite—we were trying to preserve the periphery, while completely reimagining the core.”
The original 2,746-square-foot midcentury home featured a segmented layout of small rooms and a highly congested core. While the homeowners were fond of its modest horizontal facade and straightforward approach to materials, they recognized the effects of aging and organizational flaws, which bifurcated family living patterns and severed the interior from the site’s views. SAW’s design enlarges the home to 3,457 square feet, unlocks its layout to create an open-plan central living space, and enhances its connection to the dramatic vistas. Throughout the home’s interior, fixtures and finishes were designed collaboratively by SAW and one of the homeowners, Kina Ingersoll, an interior designer. Ingersoll also selected all of the furniture.
The design is defined by a sense of expansion as one moves from the front of the house, which is one level along the street, to the back of the house, which carves down to two levels and faces a steep, lush valley. “It’s meant to be perceived as a building that is both low and extremely high,” says Spiegel.
While the entire home is an exercise in blurring distinctions between interior and exterior, this reaches its fullest expression at the rear. The kitchen-dining zone spills without interruption into living and family rooms bordered by floor-to-ceiling windows and glass doors that open to the suspended upper deck, implying layered continuity. The sensation is enhanced by interior ceiling beams that extend into outdoor space, forming a slatted trellis over the back deck. “The steel frame is continuous, defining the space of inhabitation across thresholds,” says Spiegel. “It carves volume out of the air, claiming territory even on the exterior, even without enclosure.”
Photography by Mikiko Kikuyama.
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