Adding to an existing building can often be more difficult than starting from scratch. To create an attached addition that complements but doesn’t copy the original structure, adds space that flows from old to new construction, and becomes a seamless part of the whole can challenge even the most seasoned of architects.

 

For Raouf Boutros, principal of Montreal-based Boutros + Pratte, creating a 600-square-foot addition to a traditional home in the city of Laval—less than an hour north of Montreal on the banks of the Rivière des Prairies—presented both an opportunity and a challenge. The owners had built the original home on their 20,000-square-foot property in 1990 without the help of an architect. The gabled, steel-clad roof and the exterior stone walls had a quaint feel that reflected the region’s style, but had no particular architectural uniqueness. The owners knew they would want to expand their home later on, and had thus created a concrete slab at the back of the building. When they were ready to add on, they came to Boutros with specific needs for more public living space, a new bedroom and study, and some extra storage. “While we were constrained by the existing foundation, we knew we could open the home up to the waterfront,” says Boutros, “something that was lacking in the original design.” Boutros decided that a two-story addition composed of three pieces would be best, with the new living room on the ground floor sitting evenly on the slab foundation. A new wooden floor was extended from inside to out, forming a deck that follows the stone wall of the house. On the second floor, the bedroom and study sit atop the living room in a larger volume that cantilevers out on three sides, solid enough to withstand the snow load typical of the region’s frosty winters.

 

While Boutros and his team first thought they would go with a pitched roof for the addition, exploration and formal studies brought the architects to the conclusion that a flat roof would help simplify the volumes of the house as a whole, and would preserve the dominance of the original building’s roof. “We didn’t want the new construction to compete with what existed,” says Boutros, “we wanted it to complement the old structure and open the home up to the river beyond.” Boutros clad the addition in cedar panels that will weather to a gray. “The gray will eventually be similar in color to the stone,” he says.

 

Inside on the second floor, the team created a slatted cedar bridge connecting the original volume to the addition. “It’s a way for the people who live in the house to feel how the place evolved,” he says. “It’s literally a bridge from the old to the new, and brings light into both areas. Also, the owner likes that she can see up from the ground-floor kitchen to keep an eye on the kids.”

 

The addition’s design continues its subtle intervention with natural wood cladding on walls, wood-framed windows upstairs (downstairs has a panoramic view with a wall of windows broken up with the six structural columns that support the cantilevered upper floor), and neutral brown linoleum flooring upstairs. “It was all created to fulfill the program with simplicity of design and restraint,” says Boutros. Mission accomplished.