Leonard Avenue Modular Housing

ARCHITECT Levitt Goodman Architects

LOCATIONToronto, Ontario

In 2005, St. Clare’s Multifaith Housing hired Levitt Goodman Architects to design 26 new single-resident-occupancy (SRO) units arranged around central exterior courtyard gardens for an existing affordable housing complex in Toronto’s Kensington Market neighbourhood. The architects responded to the client’s needs by designing prefabricated units and hoisting them on top of the existing roof.

After conducting an analysis of the existing structure, it was determined through geotechnical and engineering studies that the original building and bearing soil could support the additional weight without requiring any further reinforcement. To accommodate the prefabricated units, a large steel transfer grid was designed and placed on top of the existing roof. The transfer grid negotiated the new 11′-8″ structural grid of the apartment units, distributing the additional forces to the existing 18′-6″ structural column bays below. The transfer grid also provided for a service space to house the plumbing supply lines and cables running between the frame and the original roof. After all the structural considerations were addressed, meeting fire code separation requirements and providing access to the new units on the roof became a significant challenge. The existing concrete roof deck provided a fire-resistance rating that was required to separate the additional apartment suites from the remainder of the building. Building code requirements meant that the additional units had to be of a non-combustible construction.

The prefabricated construction allowed a small construction crew to assemble each frame within a controlled environment with the aid of overhead track and pulley equipment in half the amount of time typically required. This resulted in better-quality construction and allowed for more complete inspections and quality assurance.

Each SRO suite was designed small enough to be a single prefabricated module with its own individual fire separations. Factory construction started in the spring while site preparations on the “host” building had already begun. Working on two sites at once saved an estimated six months in the construction schedule. A condensed construction period minimized disruption to the original building residents as well as reducing the inconvenience to neighbours and street-level activity.

The modules were delivered to the site on the back of a flatbed truck arriving at one-hour intervals and were installed on the roof at a rate of six per day. As one module was being assembled to the transfer grid, another module was being hoisted into place. After six days, all the units were lifted and placed into position by a crew of millwrights and bridge-builders.

The design of the 220-square-foot units was based on an Airstream trailer. Studying both trailer and boat interiors, the architects developed a prototypical design incorporating built-in furnishings and finishes. Similar to a trailer, appliances and fixtures are tucked into alcoves and corners rather than being located in separate rooms. Therefore, the bathroom is not a room, but a series of components–residents use the kitchen sink for all washing and the bathtub opens up into the main living space.

The existing elevator core, as well as the two exit stair towers, were extended to the fifth and sixth floors. These extended service cores divide the exterior space into three smaller exterior courts with the apartments flanking the courtyards as two east-west bars of units. Individual apartments are accessed from covered exterior walkways, allowing for excellent natural light and cross-ventilation in each unit. Because each unit is so small, the communal rooftop space was a high priority.

In urban conditions in all major cities across the country, the scarcity of developable land in the downtown core is becoming one of the defining issues in driving new residential development out of the inner city. Rooftop intensification is part of a flexible conceptualization of housing that will offer an additional option for the industry.

Jury Comments

In the context of architecture as a tool to accomplish social housing objectives, this project was found interesting and innovative in its concept, planning and technical execution. The Leonard Avenue project was deemed an excellent example of innovation from program through all phases to on-site completion. This project allowed for the delivery of high-quality living space with minimal cost through innovative “first principles” design, and careful implementation of technical and design efficiencies. The design and construction process integrated space-efficient prefabrication technologies learned from allied industries (trailer manufacturing, etc). The effective pursuit of commendable outcomes to this housing project was also enhanced with the inclusion of sustainable design features such as green roof installations. The jury found the project demonstrated significant ingenuity being effectively utilized in the service of important social needs.