In a family photo, everyone might share the same eyes or nose or smile, but you can immediately spot the one with an extra spark, the spirit of adventure. So too the Casablanca, Morocco, house of architect Mehdi Berrada. Though similar in size and shape to other area homes, it stands out while blending in. It’s an original.

“It belongs, but it doesn’t. It isn’t a house that says, ‘Look at me,’” Mehdi says. “It’s a house that says, ‘I’m free.’”

Mehdi was born in France to Moroccan parents and they moved to Casablanca when he was three. He grew up there in houses designed by his architect father, who created bright, white homes with pure lines that melded Le Corbusier’s International Style with local vernacular. Today Mehdi has his own firm, designing houses, factories, retail spaces, and hotels.

He loves the city’s contrasts. Palm trees line elegant boulevards, while the ancient medina is a river of humanity channeled through a maze of alleyways, filled with pedestrians jostling with vendors for space. On Mehdi’s narrow residential street, the din diminishes, and even more so behind his perimeter walls. Thick tropical vegetation—false bananas, yellow canna lilies and fig trees—surrounds the house. “It’s a nest in the middle of city noises, a bunker in the jungle,” he says.

Mehdi and his wife, Sanae, an energy executive, previously lived in an apartment, but the birth of their twin boys made them seek more space. They found an unoccupied house on a small lot not far from the city center and set about replacing it. After six months of design and two years of construction, they moved in.

Immediately, there’s a clue that their home is different. The steel gates were treated with vinegar and seawater to obtain a rusty finish. Workmen who come to the house offer to put Mehdi in touch with a painter who can “fix” them, but he refuses. “I like things that age naturally,” he says. Over time, the oil from people’s hands has removed the rust and returned the steel to black at the spot where they grip the gate. “I love it,” Mehdi says of the unplanned detail. “It’s wabi-sabi.”

The house’s cube shape maximizes the use of the rectangular plot. Like in traditional Islamic and Spanish architecture, the interior is hidden from the street. The windows are covered with wide strips of rusted steel. Besides adding geometric interest to the exterior, the bars provide privacy, security, and slatted shade.

The house is built of concrete blocks, in typical Moroccan fashion, but in two layers, with rock wool insulation between them. Most of the walls are covered with a gray cement, sand, and small aggregate mix, left natural—an unusual choice in a place where paint and tile are more highly regarded than untreated concrete.

Mehdi prefers materials that can be left raw and weather well: concrete, steel, and wood. “I use materials that are made to age,” he says. “They get character from it.”

Junichiro Tanizaki’s 1933 essay on Japanese aesthetics, “In Praise of Shadows,” made an impression on the architect that is evident in his embrace of the concept of shou sugi ban. Once burned, the spruce on the living room and dining/kitchen ceilings, as well as the bedroom floors, became a chocolate brown. The ceilings are left rough, but in the bedrooms, the chevron parquet is waxed to a gleaming patina. A wall in the living room is paneled with charred oak, which turned black.

Mehdi combined the kitchen and dining area in an open-plan layout. That, too, is unusual by local standards. In Morocco, even middle-class families often have household staff, and the Berradas employ two women to cook and clean. But in most cases, the staff work and eat in an enclosed kitchen, separate from the residents. In Mehdi’s view, though, “the kitchen is a place of life” and shouldn’t be hidden away. “We have a culture of cuisine that’s very important,” he says. “Preparing meals is not just going to the supermarket.” Also, the staffers are considered “part of the family,” he says. “They eat with us. So the kitchen and dining room are one space, open.”

The living room’s glass wall slides open to the tropical “jungle” on the south side. Birds sing and butterflies dance in the oasis of calm, though the thrum of Casablanca is not far away. The double-pane glass and concrete construction keep the house cool enough in summer that plans for air conditioning were scrapped. The stairwell is capped by a skylight that retracts to create a flue, pulling in fresh air.

Upstairs, Mehdi and Sanae’s suite is on one side; the children’s rooms and Mehdi’s office are across the hall. The twins’ rooms are big enough to one day fit double beds, but small enough that they’ll choose to come out to play together. “Architecture is more than just decoration and economics,” Mehdi says. “It’s how the space will influence the way the family interacts.”

Indeed, the boys, Leith and Malik, now six years old, have an enormous playroom in the basement where they are free to write on the walls. A large window faces a light well filled with lush plants. The basement also has bedrooms for the staffers.

The family moved into the house a year ago, and it is still a work in progress. A television room is being outfitted with an enormous mattress and cushions—a nest within the nest. “I tell clients not to rush to have everything complete. It’s time that makes the charm,” he says. “You have to leave space for things to come.”