A shaft of light slants down through the clouds, flooding a mountaintop and a river valley with blue-white tones. This pastoral scene, a work in progress, fills a big canvas on artist Kent Monkman’s wall, and you can see every brushstroke, thanks to the skylight positioned just above it in the tall ceiling. With broad expanses of white walls and perfectly modulated light, this space is the very picture of an artist’s studio—and it was crafted as carefully as Monkman’s mountain landscape.

Just knock on a wall and you’ll hear a solid, workmanlike thunk. “There’s plywood behind all this drywall, so I can put in screws and hang a work any where I want,” Monkman says, relaxing on a Florence Knoll sofa just across from the painting in the open-plan room, which serves as his studio, office, living room, and dining room. “It works as a gallery as well; I use it that way when collectors or curators come to visit.”

Such flexibility is the defining feature of loft living, and Monkman’s 3,300-square-foot space has plenty of it. Located on a Toronto street that houses a chocolate factory, a crumbling car-parts plant, and workers’ houses, the home has all the character of a repurposed industrial building, with a mezzanine, polished concrete on the floor, and exposed wood trusses on the ceiling. Yet there are quiet Victorian houses next door, a pleasant courtyard out front, and a green roof, rich with multihued sedums shaded by nearby cherry trees.

On the inside, the mixture of the industrial and the domestic is largely the work of architectural designer Jason Halter, who oversaw its major renovation in 2009. “This building is really fitted out purposefully,” says Halter, a veteran of Toronto-based Bruce Mau Design, where he helped design everything from MoMA signage to a huge urban park with Rem Koolhaas. “It’s an artist’s studio, and everything that was done was done out of necessity.”

Monkman, a working artist for over 20 years, had clear ideas about what he needed in a home—and experience told him that a live/work studio isn’t necessarily the best place to reside. “For most of my time in Toronto, I’ve basically lived in my studio and storage space, surrounded by all my supplies and work,” he says.

A couple of years ago he was occupying a storefront that felt like “a bowling alley.” Given the success of his multimedia art practice—Monkman now shows at museums and major art fairs around the world—he says, “It was time to separate living and working.” So he went hunting for a new space and found this one. Once a small factory, it was the workshop of a landscape architect, Terry McGlade, who specializes in green roofs.

Seeing its massive volume—28 feet wide and 16 feet high—“I thought this place was awesome and that I’d do a cheap cosmetic renovation,” Monkman says. He bought it, asked Halter to design some hardy studio furniture, and started working there.“I used this as my annex studio at first, so I spent a while in the space. I painted here, we shot a video here.” Halter steps in: “And you were practicing tai chi here,” he says with a grin. “It’s true, I really put it to use,” Monkman echoes. “The space is wonderful. But some of the infrastructure had to be replaced, and as it turned out, you had to backtrack to go forward,” he adds.

In fact, the poor insulation, the garage-door-instead-of-windows setup, and an ancient furnace necessitated a complete overhaul. Halter was up for the job, collaborating with architect and friend Anthony Provenzano. Monkman asked them to redesign his space with a flexible plan that could shift between a studio or living space depending on his needs. Their response was to be as subtle as possible, preserving as much of the existing raw character as they could. “There was a lot of work to do,” Halter says, “but I wanted to make it look like not much was done at all.”

After Halter and Provenzano completed the initial designs, Halter and his firm, Wonder Inc., took over. The biggest changes were simple architectural fixes. Halter removed a drop ceiling, added three skylights, and replaced the garage door with a new commercial door and window system, which made it brighter and more airtight. He designed a galley kitchen for a corner of the main space and enlarged an existing mezzanine at the back, opening a wall and stretching the floor a few feet to make more space for a bedroom and bathroom.

As they worked out more of the redesign details, however, Monkman found that keeping up two rents was getting pricey—and the new space was attractive enough that he decided to move in after all. Halter listened carefully to Monkman’s requests for a building that was both clean enough to be a home and capacious enough for the quirks of his art practice. He enclosed the space under the mezzanine, creating room to conceal a Miele washer-dryer as well as a mountain of canvases, files, and supplies. “All of these cabinets were in my old space,” Monkman says. “And now they’re all here, hidden out of sight.” Along one side of the main room, Halter built a tall, clean wall as a showcase for paintings. Behind it a massive 5-by-30-foot corridor holds big pieces, hiding them with an artfully turned stretch of wall without a door.

“We had a lot of discussions about exactly how big the opening should be,” Halter recalls. “A lot of my works are very large,” explains Monkman, whose installation, video, and paintings often play with art history and representations of Native Americans. “Plus there’s space up in the rafters”—he points up to a rack hanging from the ceiling—“to store tepee poles, which is very useful for me.”

For more conventional needs, Halter designed a set of built-in shelves that run up the stairs and along the edge of the mezzanine. They’re made of Douglas fir plywood, an inexpensive and handsome material that is a standby in his projects. “I’ve always been enamored of both Frank Gehry’s and Rem Koolhaas’s use of Douglas fir,” he says. The built-ins—a perfectly orthogonal array of shelves that mirror the treads and risers of the staircase—add a hint of precision to the space, even as the wood’s whorled texture picks up on the roughness of the building.

There’s still plenty of leftover grit: The ceiling, now painted white, has an intricate array of joists and crossbeams including a set of fluorescent tube fixtures. Big chunks of stone and the brownish tint of the century-old concrete floor make it look like a rich terrazzo, adding an organic feel to the space.

But the hidden treasure of Monkman’s home is up top. Pull down an attic stair in the bedroom, clamber up to the roof, and you enter a bracingly verdant space in the treetops. A broad green roof crowns the building—the work of landscape architect McGlade, the previous owner. He planted a variety of sturdy sedums and other low-maintenance plants, which have grown up in bold splashes of colors.

Halter capped the maturing roof with a patio of ipe wood, lined with tall grasses in planters made of salvaged cedar. In the summer months, this aerie is almost hidden from the neighbors by the trees—you can just see some of the light industry and old plants down the street. The mix is a fitting complement to the building, where living and working are in a fine balance. “There’s a metal shop here, an autobody shop there,” Monkman says, pointing down the street. “But most of the time all you hear is birds.”