A new project by Spiegel Aihara Workshop (SAW) is rightfully named Complex. SAW began working on the seemingly simple renovation of a 1934 house in tony Atherton, in California’s Silicon Valley, in 2018. Over five years, the job’s scope expanded to intervening on the existing house and garage more extensively, and constructing a new guesthouse tower, another guesthouse, and a pool house, totaling some 6,935 square feet. “We like the double meaning of complex,” says Dan Spiegel, cofounding partner with Megumi Aihara of SAW, a San Francisco–based architecture, landscape, and urban design firm and 2019 Design Vanguard firm. “We used to call the project ‘Developing a Complex,’ because it started as one thing and then led to another and another and another.”

Surprisingly, SAW’s work at the site began as a subtraction—cutting into the main house. The owners, a couple who moved to California from Spain, thought the residence lacked a front, so SAW removed the entry porch and chopped into existing overlapping pitched roofs to create a more formidable facade with a cantilevering gable end, without overstepping the property’s setback.

The new front walls feature oversize doors and windows that SAW inherited—the clients had begun the project with a different team and already purchased the fenestration to use in its design. Spiegel says that, when SAW took over the job, “we had to figure out new ways to arrange all these existing materials, which was actually a fun challenge.” A slanted indentation highlights one reused door above the main entrance. It complements the many interesting angles produced by slicing into the pitched roofs.

When the pandemic nudged the owners’ children home in 2021, the renovation project morphed from subtraction to addition. Rather than tuck new bedrooms and offices into, or tack them onto, the main residence, SAW added accessory buildings; this started with a three-story tower for the teenage kids and continued from there. The site plan evolved into a villagelike composition of singular structures surrounding a communal square. “There’s a logic of aggregation,” Spiegel says, “a language that we’ve established, a way that things fit together, and a maximum bulkiness that we were willing to have in the project.”

A consistent palette of refined cladding helps unify the work. Modified Monterey pine appears in two charred finishes; Spiegel mentions the Japanese shou sugi ban burnt-wood technique that informed this. SAW chose gray slate shingles for both their fire retarding qualities and their beauty. White ultracompact porcelain panels were influenced by the sensibility of the Spanish owners. On sunny days, they catch the shadows of the property’s oak trees.

SAW saved numerous mature oaks in the front and back yards and a magnolia near the pool as part of its landscape plan, overseen by Aihara. New plantings are integrated with the old and were chosen to flower and fruit throughout Northern California’s mild seasons. Spiegel says, “We wanted it to be so that even in the middle of winter, there was quite a bit of color around.”

The landscaping helped SAW to unify the complex interiors. High windows throughout the project focus views into the branches while maintaining privacy, even in the pool house’s sauna. “You share the same landscape references without seeing one another,” Spiegel says. Interior windows and wall cutouts offer surprising vistas from room to room—again, integrating the design.

In fact, surprising details everywhere are the real joy of the project. Two light monitors disguised as chimneys illuminate hallways in the main building. A glass-enclosed walkway connects a lounge to the guesthouse tower. A diffused skylight over exposed beams brings a soft glow to the other guesthouse.

Some of the surprises—like a tapering bathroom counter in the tower and a trapezoidal window in the guesthouse—seem introduced to reflect the faceted forms produced by cutting into the main building. It is as if the complexities of Complex were not enough, and SAW needed to create an even bigger challenge for itself.

Spiegel admits his delight in the experimentation that residential work allows, especially with a willing client. He notes the many models—both physical and virtual—that SAW depended on to make angles, sight lines, setbacks, lighting, inherited doors and windows, and all the rest work together. But ultimately the measure of the project is experiential rather than logical. Whether sitting under the east-facing terrace or standing on the tower’s balcony, there is a united feel to the place, one of an irregular but coherent family compound. And in this sense, Complex is simply successful.