Deciding where to build a house tends to be a one-two punch. Prospective owners not only have to love the land they buy, but they also need the foresight—or that of an architect—to imagine their future home on it. But looking at properties can become tiring fast, and when decision fatigue sets in, everything starts to blend together. For the lucky ones, there’s a moment in the search, however exhaustive, when things just click. South African couple Graeme and Toni stuck with it for five years until they connected with a lot in the suburbs of Johannesburg.

“When we came across this property, there was a beautiful old acacia tree on it, and that’s what first attracted me to the land,” says Toni, a design-loving stay-at-home mom of two boys, Jesse, 14, and Jamie, 11. “It’s the quintessential African tree—a symbol of the continent. I wanted to see that tree every day when I woke up. I wanted the house to wrap around it.”

Because the lot was created from a subdivision, it had a swimming pool that had belonged to another nearby home, which needed replacing. It was otherwise open, and Toni and Graeme envisioned constructing a family home by sourcing as many materials and products locally as possible. “We’re proud South Africans,” says Toni.

The couple sourced their design talent locally, too. Toni found architect Gregory Katz, who also teaches at the Graduate School of Architecture at the University of Johannesburg, on home renovation show Top Billing a few years ago and has followed his work ever since.

“We loved his approach to the project,” Toni says, referring to the show. “He renovated a home in town and redid each room to get the most efficient use out of it. We connected with his principles about building smaller and more purposefully. After seeing his work, we said, ‘If we ever build a home, we’re going to use Greg Katz.’”

Toni and Graeme’s new home, which riffs on regional modernism, comprises two wings on either side of a grassy courtyard: one with a public zone containing the living room, kitchen, and dining room, and another for the bedrooms. A bridge-like breezeway with glass walls connects the two, acting, as Katz describes it, “as an umbilical cord.” Given the site’s grade change of four feet, the public wing sits higher than the bedrooms, a change that Katz says is most notable when standing in the courtyard. “It’s quite an exaggerated moment,” he says of the breezeway’s stepped appearance. “It’s almost like an earthquake happened, shook things up, and they didn’t quite settle back down.”

Since South Africa has frequent planned blackouts, called “load shedding,” that can leave people without power for hours, Katz optimized bringing daylight into the home by using glass walls around the perimeter of the courtyard. “You never need to switch a light on in the daytime,” says Toni. Deep overhangs on both wings help keep the interiors cool in the winter and warm in the summer, reducing the home’s reliance on heating and cooling systems.

In addition to the glass, Katz used concrete—“a nod to the heyday of modernism in Joburg,” he says—brick, and aluminized-steel window frames that are powder-coated in a deep red. Doors throughout are orange—a welcoming pop of color that Toni wasn’t sure about at first, but has grown to love. “I’m so glad Greg wore me down,” she says of the palette-brightening additions. “They are beautiful!”

A double-sided fireplace provides some privacy to the living area. Originally, Katz planned to plaster it with cement to create an ultrasmooth surface, but once the design team saw the initial roughness, they liked the look and decided to keep it. “It looks like a rock formation,” says Katz.

In the wing with the common spaces, the kitchen, dining, and living rooms are open to each other. A six-seater kitchen island is made from South African granite sourced through a local quarry. On the porch just outside the dining area—which has a table, chairs, and bar stools made by local wood manufacturer Houtlander—is a sunken concrete conversation pit with an oculus directly overhead. “We spend a lot of time there as a family,” Toni says. “It has built-in outlets so everyone can keep their electronics running.”

Across the courtyard, the bedroom wing employs the same base palette of concrete and glass, but Katz worked in cork and sliced brick (the former as wall treatments in the boys’ bedrooms; the latter used as tiles for the wall and floor in the primary bathroom). “Modernism can often feel very cold,” Katz says, “but the brick and colors really warm things up.”

A green roof planted with native plants and grasses—the crown jewel of the house—is accessible by a custom Japanese-inspired concrete ladder. Every afternoon, Toni heads to the roof to enjoy a cup of tea (and a little quiet). “It’s very relaxing; even the kids will leave their gaming room to go up there,” she says. “We’ve got a really special setup. It’s a little gem in the suburbs.”

As for the acacia tree, Toni can see it from multiple places in the house. Katz even created a small, half-moon-shaped cutout in one of the home's overhangs to keep from lopping off one of it’s branches. “That tree was a determining factor in where we positioned the two wings,” he says, “and it turns out that it guided us just right.”

Project Credits:

Architect of Record: Gregory Katz Architecture / @gregorykatzarch

Builder/General Contractor: Kintro Construction

Structural Engineer: ConsulTauri Design

Cabinetry Design: SkyBlock Group