A zinc-shingled roof with a compound curve defines a house
Photo: Greg Van Riel
The mathematical formula for a Bézier curve with three given points is B(t) = (1- t)[(1- t)P0 + tP1] + t[(1- t)P0 + tP2.
Mathematicians often speak of the beauty of a math equation, but when you see this formula put into practice in the roofline of a custom home in North York, Ontario, Canada, the beauty comes to life. Then clad that roof in zinc shingles that impose a texture and formality on the structure, and the beauty becomes elegant. And introduce weather, and the roof becomes a kinetic sculpture that forms snow into cones connecting the eaves to the ground.
Custom home builder Farhad Kazmian, ABOND Homes, North York, worked with Toronto- based architect Tania Bortolotto to create a personal residence in an established neighborhood that fulfilled his desire for a contemporary design.
Kazmian and his family had lived in the house since 2011, and when he remodeled, he wanted to keep the courtyard with lap pool in the front of the house, which would no longer meet zoning requirements. So, he needed to wrap the home around the courtyard. Bortolotto’s solution was an L-shaped house that featured a modified Aframe on the leg facing the street.
Photo: Tom Arban
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.”
Kazmian was worried about the difficulty of working with slate as well as the weight. “It was my insistence on zinc, which is lighter, more durable and better looking,” he says. “You can cut it and carve it more easily.”
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.
Photo: Farhad Kazmian
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.
Alpro also installed a custom-fabricated standing seam roof made from stainless steel on the side and back of the home.
Photo: Greg Van Riel