Making a statement

Ryan Schott, a marketing executive for a real estate firm, has 10 types of marble in his Summerhill house. In the foyer, there's a dusky serpentine. The stand-alone fireplace is soot-black but with fissure-like streaks of white. And the cladding in the ensuite bathroom is as intricately veined as leaves on a sapling. The house is a stone collector's dream.

Here's what you won't find in it: spindly chairs, tanned leather or rustic finishes. The place evokes a time before Scandinavia conquered the design world. It's opulent, like an uptown hotel. "A lot of people don't know how to apply black to a space," says Mr. Schott, who isn't afraid of sharp contrasts and dark accents.

The original home was a classic Toronto semi-detached: two bay windows topped with a gable. The interiors had cave-like rooms, dull wallpaper and egregious shag carpeting. Mr. Schott hired Toronto's blackLAB architects for a renovation so extensive it's more like an original build. Despite the limited space – the property is less than 17 feet wide – Mr. Schott wanted loft-like ambience. Andrea Kordos, the project lead, welcomed this challenge. "We like it when clients come to us with a specific brief," she says. "It's why we got into custom architecture in the first place."

She preserved the front façade and building envelope, thereby avoiding a run-in with the committee of adjustment. There are worse Toronto bureaucracies: The committee is often receptive to good ideas well justified. But the process is time consuming and expensive, and if you go through it, you might as well invite your NIMBY neighbours to phone in and have their say. They'll do it anyway.

The original home had two floors plus an attic; the new one zigzags upward by half-steps. On the ground level is a long, slender kitchen-living area. The master bedroom sits atop the lounge on the front side of the house. There's a TV room (or loft) at the back, a half storey up from there, and the guest suite is at the front again, a further half storey higher than the loft. "We kept the original square footage but reorganized the floorplan to optimize volume," Ms. Kordos says. The kitchen has 14-foot ceilings, which, given the overall height constraints, wouldn't have been possible in a conventionally stacked structure.

At the centre of the house is a 28-foot-high stairwell with diagonal open-tread bridges connecting the floorplates. Above it are five curved skylights, which bring sunlight into each of the half-floors and the main space below. It's a graceful solution to what Ms. Kordos calls "the traditional conundrum of the Toronto semi-detached: getting light deep into a narrow property."

The built-ins are both practical and thematically on point. At the base of the stairs, the railing snakes around the dining table and morphs into a banquette – an elegant feature that saves precious square footage. (Stand-alone furniture always takes up more space than millwork.) The 17-foot-long kitchen island and double-height cabinetry emphasize the tall, elongated nature of the room. And the white-oak floors have a metallic glaze, creating the nourishing ambience Mr. Schott was going for.

BlackLAB handled the architecture and Mr. Schott took charge of the interior design, reconciling aestheticism with a kind of fashion-forward aggression. "I like every piece to be a statement," he says. Interior work can be exhausting, which is why even design-savvy people sometimes cop out and head to Wal-Mart. Mr. Schott, however, went all in, doubling his renovation budget and, in under two years, realizing a fuller vision than most homeowners do in a lifetime.

No piece was chosen for functionality alone. The pendant lamps, for instance, fill the rooms not only with light but also with texture and tension. Above the dining table hangs an aluminum semi-sphere from Catellani and Smith; its interiors are gilded with silver leaf and as rutted as the lunar surface. The chandelier in the loft resembles a firework in suspended animation: Shell-like crystals dangle from thin metal strands casting a web of shadows on the wall.

Although many of Mr. Schott's pieces are classically elegant – the dining table is a glass ovoid on a pearly white base – there is another impulse at work: the gothic. Not "gothic" like Wuthering Heights or eighties teen culture, but gothic in our moment, the era of Rick Owens, Kanye West and Blade Runner 2049. Think: macho, grotesque, seductive.

In the TV room are two tables by Spanish master Patricia Urquiola, their surfaces as ridged as brain matter. In the basement are a pair of steer's horns as beautifully marbled as any of the stone finishes. The bedroom has a bench upholstered in dyed pelt with a metallic-teal sheen; it's an unholy mashup of organic and synthetic textures. Nearby is a table mounted on three – okay, "tentacles" may not be the correct term, but it's more accurate than "legs."

Make no mistake: This is a sophisticated dwelling, not a roadside attraction. Mr. Schott has an eye for balance. He incorporates surreal flourishes as deftly as he deploys the colour black. The process is intuitive and difficult to describe. "I'm not a designer," he says, "so I don't do design speak, but I know that I want a distinctive setting."

Above his foyer hangs a rectangular light comprising 25 upside-down bulbs in a grid-like formation. Mr. Schott's sensibility is upmarket, bold and sometimes theatrical. It's fitting that, when entering his home, you must pass beneath a marquee.