When architect Lorcan O’Herlihy’s twin sons were born, in 2009, he and his wife, Cornelia Hayes O’Herlihy, were living in “The Vertical House,” in Venice, California, which he’d designed and built six years earlier. That urban dwelling was great for a couple without kids, but the abundant stairs challenged toddler safety. “I longed for a flat home,” recalls Cornelia, an actor known to family and friends as Leila. But suitable and affordable real estate was hard to come by. Nearly a year later, she and her husband bought a foreclosed-on house in the hills of Malibu. “It was completely generic, nothing special, stripped of its fixtures and appliances, though structurally sound,” says O’Herlihy of the 2,000-square-foot building (circa 1998) on a sloping half acre. During their first decade in residence, the couple made a series of gradual improvements, including a kitchen renovation and restoration of the hardwood floors. Then, about two years ago, they took the plunge and re-envisioned the entire place. “But we still retained the footprint and massing,” says the architect. “It was about surgical interventions and strategic moves to transform the house to suit our family.”

That project, completed last year, hearkens back to O’Herlihy’s childhood in Malibu. Born in Ireland, as was his wife, he moved with his parents and four older siblings to this coastal enclave of Los Angeles when he was a year old. The family remained there for much of his childhood. His father, Dan O’Herlihy, was an actor who’d been nominated for an Oscar in 1955 (he lost to Marlon Brando in On the Waterfront). “We were very fortunate to live in Malibu,” Lorcan recalls. “We certainly didn’t have a luxurious lifestyle. But we loved being right by the ocean—there was a rough, remote, off-the-beaten-path quality to Malibu. It had a culture of writers, directors, artists, musicians, poets. And, even with more recent changes, some of that edgy rawness has survived.”