For Joe Day, moving back to Los Angeles in 1999 ended a protracted spell of California dreaming. The designer had suffered through swampy summers in Washington, D.C., in the early ’90s when his wife, Nina Hachigian, was working at the Clinton White House and Day was on sabbatical from the Southern California Institute of Architecture (SCI-Arc). Washington reluctantly became the full-time home for the couple in 1997 when Hachigian, a Stanford-trained lawyer, went to work at the Federal Trade Commission. Day took a job at HNTB, a large architecture firm in Alexandria, Virginia, but commuted to L.A. monthly to keep up with his own projects, including a clothing line called Dayware and the renovation of a house the couple had purchased in Silver Lake. After less than a year, Day left HNTB to work exclusively on his California projects. The cross-country shuttling between D.C. and Culver City, where Day ran his own firm within a design collective called Hedge, became more frequent, the pull of Southern California, stronger.

By 1999, Day and Hachigian were both back in L.A. full time. They moved into their Silver Lake home before work began on the addition to the front of the house so they could get a better feel for living there and make any adjustments to the design. Their daughter, Sosi, was on the way, so even the most educated guesses about life in the house would inevitably change with her arrival.

Though they were thrilled to be back in Los Angeles, years of city living on the East Coast cast a sliver of doubt on the couple’s change of address. “We were both a little leery about moving into a single-family home,” explains Day. “Over the years, we lived in half a dozen apart-ments, all of them in dense urban areas. So we were used to interacting with people. We were worried about the change, the privatization that happens with house living.” That aversion to semi-suburban isolation became an important jumping-off point in Day’s design.

The Day/Hachigian home is located just up the street from Rudolf M. Schindler’s 1934 Oliver House and about three miles from the Griffith Observatory. The original structure, built in 1947 in a style Day jokingly calls “tract moderne,” sat high on a hillside lot, looking out toward the domed observatory. Despite its privileged vantage point, the house pretty much turned its back to the street. The only appreciable exterior living space was a private garden on the back side of the house; out front, there was just one window and no outdoor spaces from which to gaze at Silver Lake, Griffith Park, and the sprawling metropolis beyond. The aim of Day’s $440,000 renovation, which took four years to complete, was to engage the neighborhood and the city at large by opening up the interior living spaces to the street and adding new outdoor spaces overlooking the more public realm of the street.

Day demolished the original hip-roofed garage down to the foundation and replaced it with a simple, clean-lined box with a perforated stainless steel door. He added 620 square feet to the original 2,700-square-foot home, expanding the existing first floor of the house—one level uphill from the garage—toward the street and creating a guest bedroom (with its own balcony) atop the garage. The guest-room roof in turn became a large terrace off the living room and screening room on the main floor, another flight uphill. In addition to the guest room, the first level contains a second bedroom and a large shared study for Hachigian and Day.

All of the rooms flow into each other and out onto terraces in front and a shady garden in back with a hot tub and lap pool. Day tore out many of the original interior walls that made the house dark and cellular, replacing them with planes of sandblasted reeded glass and trans-lucent acrylic to connect the rooms visually and brighten the interiors. Different surface treatments of these materials create varying degrees of translucency and veiling throughout the home.

One element that really pushed Day’s ideas of blurring public and private space is an LED sign mounted above the front door. That one small gesture creates a dialogue between the house’s inhabitants and the world outside. The sign flashes messages that run the gamut from the philosophical (quotes from André Breton and Joan Didion) to the personal (announcements of Sosi’s birthday) to the civic-minded (reminders to vote, cheers for the Lakers, encouragement for firefighters during last fall’s forest fires). Like other elements of the design, the sign is a synthesis of multiple influences, including airport diagrams and the backlit street numbers found on the exterior of many L.A. houses.

Day began designing the house while still in Washington and, in a somewhat wry twist, brought a material sensibility gleaned during his East Coast tenure back to California. While at HNTB, he worked on major airport renovations in Houston and Salt Lake City. (“The nice thing about airports,” says Day, “is that everyone agrees they ought to be modern.”) The projects gave him access to the firm’s expansive library of industrial material samples. “A lot of the decisions about the palette of the house came from having access to such an interesting range,” admits the architect.

Some of the materials that worked their way into the design have a direct provenance from Day’s airport projects, including the corrugated-aluminum decking and paneling. He brought in other industrial components—bleacher seats, restaurant floor mats, brushed and perforated stainless steel—that take on a warmer cast when juxtaposed with bamboo, cork, and bluestone floors and dry-stacked planters and retaining walls outside.

Day is conscious of the continuum of California modernism that his house fits into, a legacy that includes Schindler and Richard Neutra as well as the late Frank Israel, with whom Day worked and taught. But the influences on his house extend beyond the West Coast: A semester in Switzerland, where he discovered the work of hyperrational minimalists like Peter Zumthor and Herzog & de Meuron, and the expressive, exuberant architecture of post–Rem Koolhaas Dutch architects he studied at SCI-Arc plugged Day into a broader discourse. “Many of the decisions on the house—everything from window detailing to the LED sign to the perforated sunscreens—relate to that dialogue,” explains Day.

As in Schindler’s classic California houses, custom furniture is an important part of Day’s design. He collaborated on several pieces with his brother-in-law, Garo Hachigian, a furniture designer and fabricator based in San Diego, including built-in mahogany benches on the guest-room terrace and a pair of outdoor wood dining tables and benches inspired by German beer halls. Hype Arc Design + Build fabricated the aluminum-and-plywood frame of Day and Hachigian’s bed and a bent-aluminum chair in the downstairs study, as well as the garage door and a corrugated stainless steel awning on the front deck.

Though Silver Lake is still far from the busy sidewalks of New York and Washington, Day and his family are finding life in a single-family home less isolated than they feared. Their revamped home has not only connected them to the landscape and the city, it has also sparked interaction among the neighbors—thanks almost entirely to the LED display sign on the exterior. “Sometimes they’ll leave us notes suggesting that it’s time to change the message or telling us they really liked a particular one,” explains Day. “I think it’s an experiment in public address, but sometimes I worry that it’s an imposition on the world, broadcasting 24/7. I guess I’m still self-conscious about it.”