Architect Tania Bortolotto, founder and president of Bortolotto, Toronto, designed a personal residence in an established neighborhood for custom home builder Farhad Kazmian, ABOND Homes, North York, Ontario, Canada. The central feature, a zinc-shingled curved roof imposes a texture and formality on the structure, and the beauty becomes elegant. Introduce weather, and the roof becomes a kinetic sculpture that forms snow into cones connecting the eaves to the ground.
A roof defines the character of a house through its shape and texture
Design award judge, Stephen Van Dyke, AIA, LEED AP, partner, LMN Architects, Seattle, said, “It really set the bar for craft in metal roofing. I just want to touch it and check it out.” Brent Schipper, AIA, LEED AP, principal, ASK Studio, Des Moines, Iowa, another judge, spoke to the inherent nature of the roof itself. “This roof is so beautiful as a roof,” he said.
A Remodel with Three Requirements
That wasn’t by accident. Bortolotto speaks to the importance of the roof in differentiating this design. “When Farhad called, he said, ‘I don’t want a modern box. I want a modern house, but I don’t want a box,’” she says. “Designing a modern house and sloping the roof can be challenging. Getting the proportions right. Getting that slope to be innovative and creative. It’s much easier to design a modern box and cut out the windows. This is just a very different animal.”
That was the first criterium. The second was that the house blend into the neighborhood, which was characterized by newly built, traditional sloped roof homes. The third criterium was to retain the front courtyard, which included a lap pool that was grandfathered into the zoning requirements. Those elements pushed the design in a certain direction. Bortolotto’s solution was an L-shaped house that featured a modified A-frame on the leg facing the street.
That created a different set of problems. “The dilemma was how to connect the two parts,” says Kazmian, “without creating an imbalanced L-shape. I also was adamant that I wanted a very contemporary home and not a faux historic home or a modern home with a flat roof.” In the variable Toronto weather, flat roofs are “just not resilient enough for this climate,” he says.
Despite the desire for that kind of differentiation, Kazmian says, “I wanted the house to fit in the texture and architecture of the area. Tania does amazing work, and she had a particular house up north with a modern sloped roof that was built out of slate.”
“We must have had a 100 different concept options,” says Bortolotto. “Working with shaping the form. We started carving out the form around the pool and created the double curve roof. The roof is the actual character of the house. It becomes a façade at some point.”
One of the models for the house was a project Bortolotto did with a slate roof. “What we really liked about that roof was that it had patterning in it,” she says. “The tiles had diamond shapes. We really liked that overlapping of shingles.”
But slate is heavy and costly and difficult to shape on a curve. Zinc shingles provided a lighter option. “We started to explore with metal and we were looking for a material that could create a lot of pattern and give it a lot of texture,” says Bortolotto.
A compound curved roof is more easily done on paper than framed and shingled in real life. Using steel beams and strapping laminated veneer lumber and pulling it in tension to the beams, created the curve. Each rafter had to be individually cut and placed.
It fell to Alex Prothmann, president and CEO of Alpro Sheet Metal Ltd., Angus, Ontario, to figure out how to fit the shingles to the curved roof. “When the framers left,” he says, “they were giggling, and I said, ‘have fun boys.’ In my trade, I like a challenge, and I like to be the one who accepts the challenge instead of saying ‘we’re too busy.’”
Make no mistake, it was a challenge. Alpro employees fabricated architectural-grade zinc from RHEINZINK America Inc., Woburn, Mass., into 20,000 roof tiles. “There were probably eight different sizes,” says Prothmann, “and about four different lengths as well as combinations of all those. We actually did a layout grid system like throwing a fishing net over the entire surface of the roof. That guided our installation and told us what sizes to use.” From flat to finish, the company was able to do about 200 tiles a day. Prothmann also custom-fabricated the snow stops, which were inspired by European designs.
One of the driving forces behind the steep-sloped roof was the importance of dealing with snowfall in Toronto. The custom-cut snow stops addressed that issue to some extent, but it was the curve and slope of the roof itself that offered a unique and kinetic solution.
The corner by the main entrance provided a funnel for the snow that allowed it to pour down the roof and accumulate near the front door, creating a stalagmite that reaches up to the roof. The result is a snow sculpture, which is an extension of the roof itself.