Raise the flat roof
One detail Shawn Thomas was adamant about having on the house was a flat roof, but budgetary constraints forced some trade-offs
On a sunny day last week, Tory Crowder stood in the middle of Glenaden Avenue, casting an appraising and somewhat anxious look at the shallow A-shaped trusses that appeared earlier that morning on the roof of the house she and her husband are building in their leafy Etobicoke neighbourhood.
"I can definitely see the roofline," she said, cupping her chin in one hand. Ms. Crowder, 40, mused aloud about what her husband, Shawn Thomas, would think when he saw the latest development. After all, when they were going back and forth with their architect over the design of what was supposed to be a modernist home, Mr. Thomas was very adamant about one particular detail: It had to have a flat roof.
Anyone with an even passing familiarity with residential design trends in Toronto will attest to the fact that modernist is very in, but this spare, geometrical mid-century style can pose unexpected structural challenges, especially for those with tight budgets.
In Mr. Thomas and Ms. Crowder's case, they're building a 2,700-square-foot home, which is slightly smaller than many new builds. The couple, who have three young children, had initially decided to extensively retrofit the 1946 home they'd bought in 2009. But they opted for a complete rebuild when one of their contractors convinced them that starting over made more sense financially.
As they rebooted the design process, they soon realized that the width of the house (34 feet on a 40-foot lot) and their desire to have open interior spaces on the first floor were conspiring to add some budgetary wrinkles to that dream.
According to their architect, Altius Architecture Inc. principal Graham Smith, a flat roof posed all sorts of complexities that would drive up the cost: additional footings and load-bearing walls, engineered joist beams, more expensive injected insulation, specially designed roof ventilation systems and a commercial membrane capable of keeping the water out. As Mr. Smith observed, "A lot of people go to a flat roof and use inexpensive membranes, and then wonder why they leak."
His solution: a very gentle sloping roof – rising at a 1:3 ratio – with strategically designed overhangs both in front and back that would effectively block the view of the peak from the immediate vicinity of the home.
Trusses, he explained, distribute load effectively and provide plenty of space for conventional insulation. He differential in cost compared with a flat roof, he estimated at two to four times, depending on the choice of materials.
Mr. Smith added another rationale, although it appeared to be less of a top-of-mind issue for his clients: the jutting over-hangs, deployed to conceal the peak, provide a passive solar strategy that affords their south-facing house with natural cooling in the hot summer months. "It's a very, very efficient way of building."
Mr. Thomas and Ms. Crowder both admit that when they began discussing the project three years ago, he was most invested in the prospect of a flat roof as integral to the contemporary look they sought. "When we were thinking of what we wanted the house to look like, the vast majority of the places I found myself drawn to had flat roofs," the 43-year-old wealth manager said. "It was totally aesthetic."
What's more, he wasn't overconcerned about water infiltration, even though many friends warned him about the dangers of leaks.
Mr. Smith's design, however, had to fit within their budget, and he first proposed a ridged roof that sloped from front to back.
"To me," Mr. Thomas said, "it would be more visible than I wanted."
Seeking to balance his clients' constraints and their goals, Mr. Smith decided to demonstrate that his proposed low-slope roof would deliver the modernist goods. He created 3-D images that allowed Ms. Crowder and Mr. Thomas to look at the house from all sorts of directions and vantage points. Long before the wrecking crews knocked down the original house, the three spent hours walking up and down Glenaden, looking at the lot and comparing the vistas with Mr. Smith's computer renderings.
Eventually, Mr. Smith's architectural geometry won over Mr. Thomas. "It is going to be pretty hard to tell it's not a flat roof."
Mr. Smith adds: "You have to be four or five houses down the street to get a perspective of the roof structure."
Still, after seeing the trusses go up last week, Ms. Crowder couldn't quite tamp down her misgivings. Yet, she also noticed a new opportunity to add to the look they were after: Installing a green-roof treatment on those extended overhangs that were added mainly to obscure the peak from a street-level perspective.
As Mr. Thomas points out, a lot of the work that goes into building a house from scratch involves compromises and rolling with the process. "Until you really go through it, you probably don't have the same appreciation of the trade-offs."
Globe Real Estate is following the construction of a new 2,700-square-foot home in an Etobicoke neighbourhood that has become, like many Toronto residential enclaves, a hotbed of demolition and rebuilding activity. The first instalment, published in April, is here