UP ON THE ROOF
Montrealers moving up and out for summer
Flat Montreal rooftops can be transformed into urban oases — but architect Owen Rose warns homeowners to involve the right kinds of professionals, and to be willing to wait out lengthy municipal permitting processes.
Rooftop decks, or terraces, and green roofs are a growing trend in densely-populated central Montreal neighbourhoods, including the Plateau, Rosemont and StHenri. Streets are lined with sunny, flat-roofed duplexes and triplexes, and the residents of these buildings’ top storeys usually have no yard access — which makes developing the rooftops for outdoor use an attractive option.
“You can do a great rooftop terrace, but when it lands in the basement, it’s not as fun,” said Rose, who has been designing rooftop terraces and green roofs since 2004. “The warning is always structure, structure, structure.”
In addition to working with an architect, and consulting local
borough offices about specific requirements, like railings, Rose said, homeowners should consult with a structural engineer who can assess what interventions are needed to ensure a home can support rooftop development.
Green roofs, which Rose likened to having a backyard on the roof, are the most extensive — and expensive — rooftop developments.
Installing a heavy layer of earth on top of an existing home, he said, often requires a serious structural overhaul. “That’s why the rooftop terrace is the solution that most people are opting for, because it’s the most cost effective, fastest to build, relatively easy to get approved, and structurally, relatively easy to support.”
Before architectural drawings can be brought to life, permits are required by local boroughs, he said.
“People get frustrated in the spring when they decide to build a rooftop deck or green roof, and then the permit process takes so long, the project is impossible to realize (that) summer,” Rose said. He said it can take three to four months before permits are issued.
The ideal time to start planning for a rooftop development, he advised, is the end of summer or early autumn. “Then, you can really go through the ideas while it’s still warm and light out.”
After developing plans in the fall, Rose advised initiating the municipal permit process by early winter. As that process unfolds, he said, homeowners can seek out a general contractor and discuss costs.
“As soon as the spring thaw arrives, you get your general contractor up on the roof,” Rose said.
In 2008, Étienne Richer and Élise Boyer bought a Villeray cottage that had previously been converted from a duplex. Two years ago, they built an extension off the back of it whose structure could hold a significant load. Last summer, a hot tub and a green roof with plants like a plum tree and raspberries were installed above that extension, Richer said. On the previously existing rooftop, a much lighter cedar deck was built, which now accommodates a dining area, planters with herbs and space for a small barbecue.
Minus the hot tub, Richer estimated the costs to develop the terrace and green roof were $18,000, including the work of a structural engineer and architect, which were subcontracted by their contractor.
Richer said the municipal permit process was long; it took four months for the final plans to be approved.
However, despite the waiting, he also said the process was smooth and easy. To access the roof, Richer, Boyer and their children use a steel staircase accessed from their back balcony.
Rose noted that interior staircases to the roof are also an option. “Although it’s more expensive, the benefit ... is that you can also create with that a light well,” he said, especially if the stairwell is built in the centre of the apartment below. When windows or doors are kept open at the top of the stairwell, Rose added, it also allows hot air to escape from the building.
Coopérative Cercle Carré is a seven-storey cooperative in Old Montreal with housing units for about 60 artists and cultural workers. Their new rooftop development, designed by Rose, includes a green roof on one-quarter of the roof, with plants like strawberries and chives, and separate area with connected square and circular terraces, which are surrounded by river rocks and 40 movable garden planters.
Paul Neudorf, a resident who coordinated the rooftop development, said the project will increase the neighbourhood’s bio-diversity and reduce the effects of urban heat islands.
“The idea all along was to have a space for urban agriculture,” Neudorf said. “We built it because we want to reduce our ecological footprint.”
The terraces are made of Quebec white cedar, which Rose said is his favourite wood because it’s durable, local, smells great and is beautiful.
Unlike duplexes, triplexes and smaller multi-unit homes that require municipal permits, the multi-storey Cercle Carré building fell under the scope of the Régie du Bâtiment du Québec.
“It was a difficult process with Régie du Bâtiment,” Neudorf said, adding that provincial green roof guidelines were announced after the housing cooperative had its initial design, so they were forced to redesign the project and separate the green roof element from the wooden terrace.
Including professional fees, materials and permits, Neudorf said the rooftop development cost about $90,000 — $20,000 of which came from Environment Canada’s EcoAction program.
Rose estimated that for modest residential rooftop decks, homeowners should expect to pay between $35,000 and $40,000 to have it done properly.
“There are ad hoc rooftop terraces that have been built,” Rose said. “The danger is that they haven’t been properly assessed by structural engineers.”
Rose said the risks of such doit-yourself rooftop decks include unsafe accesses and railings, or no railings at all, compromised roof waterproofing, and more seriously, compromised structure. “Structure in the summertime is not where it counts,” he said.
“Wintertime is when the problems will come … in March under a metre of wet, heavy snow.”