1120 Ossington: Fast, Prefab Mass Timber Housing in Toronto
Jul 24
5 min read
Updated: Jul 25
In a city where the need for deeply affordable housing consistently outpaces its delivery, speed can feel like the enemy of good design. A new supportive housing project on Ossington Avenue in Toronto argues otherwise.
At just three storeys and 25 homes, 1120 Ossington is a small building carrying an outsized idea: that mass timber and off-site fabrication can deliver housing for people exiting chronic homelessness without sacrificing comfort, safety, or care. Completed in December 2024, it offers a working answer to one of the housing sector's most persistent questions — how to build both quickly and well.
Developed by St. Clare's Multifaith Housing Society and brought to technical completion by the architecture firm mcCallumSather, the project turns a sliver of surplus land into 25 permanent, rent-geared-to-income homes, with rents tied to what each household can actually afford. It sits beside a former church that has been converted into supportive housing, adding new homes to a neighbourhood already familiar with that role. The result is less a single building than a case study: proof that mass timber, prefabrication, and careful infill planning can move at the pace the housing crisis demands.
1120 Ossington. Photography by Riley Snelling 1120 Ossington. Photography by Liron Weissman
By the time mcCallumSather joined 1120 Ossington, many of the project's biggest decisions had already been made. Municipal site plan approval was secured, the building's overall shape and footprint were established, and its exterior character had largely taken form. What remained was, in many ways, the harder task: turning an approved concept into a building that could actually rise on a narrow urban lot, on a tight timeline, without disturbing the surrounding block. That work fell to mcCallumSather's team, who took on the technical design, coordinated consultants, and prepared the project for a construction method still uncommon in supportive housing — prefabricated mass timber.
The site itself tells its own quiet story about how affordable housing often has to fit into a city rather than reshape it. 1120 Ossington occupies a surplus portion of land beside an existing church that had previously been converted into supportive housing, adding 25 new homes without expanding the building's urban footprint or requiring new infrastructure. It is infill development in its purest form: a modest act of densification that asks little of its surroundings while offering a great deal to the people who will live there. In a city short on land and long on need, that kind of restraint is its own kind of design achievement.
1120 Ossington. Photography by Riley Snelling 1120 Ossington. Photography by Liron Weissman
If 1120 Ossington offers one lesson to the broader housing industry, it is that when prefabrication is involved, the real construction happens long before anything reaches the site. Many of the building's components were manufactured off-site, engineered to precise tolerances before a single panel arrived on Ossington Avenue. The structural frame and enclosure were built from three-ply cross-laminated timber (CLT) panels, cut with computer-guided precision by Element5 using Ontario-sourced wood. Tilted upright and locked into place, the frame and enclosure went up in just 17 days. For a narrow site in an established residential neighbourhood, that speed was not a bonus; it was the difference between a manageable construction process and a disruptive one.
Because the lot was so tightly confined, the building had to rise in careful stages, with the rear portion assembled first to accommodate crane operations before work shifted to the front of the property. Even with this level of planning, the ordinary friction of construction still found its way in. One interior wall was modified mid-build to gain roughly three inches of clearance in a unit's kitchenette, a small adjustment that allowed the space to meet accessibility requirements without altering the broader layout. It is a small but telling detail: even in a highly technical, prefabricated process, good architecture still comes down to inches and a willingness to adapt. Precision, in this case, was not a constraint on creativity — it was what made the project possible at all.
1120 Ossington. Photography by Liron Weissman 1120 Ossington. Photography by Liron Weissman 1120 Ossington. Photography by Riley Snelling
The efficiency of 1120 Ossington's construction was never the point in itself; it was a means of getting people into safe, permanent homes sooner. Each of the building's 25 self-contained units includes its own kitchenette and private bathroom, giving residents a genuine sense of independence. Shared indoor spaces are set aside for community programming and resident services, the kind of everyday supports that turn a building into supportive housing rather than simply housing. It is a model built around autonomy without isolation — private enough to feel like home, connected enough to offer support when it is needed. That balance, more than any material or technique, is the heart of the project.
That same care extends to the building's long-term performance. Designed to exceed the energy benchmarks set through the Canada Mortgage and Housing Corporation's Rapid Housing Initiative, a federal program aimed at fast-tracking affordable housing across the country, 1120 Ossington features a high-performance building envelope, a Passive House-rated slab assembly, and mechanical systems built to keep operational energy use low. Energy modelling suggests the building will perform roughly 40 percent better than the National Energy Code for Buildings baseline, the standard benchmark for energy-efficient construction in Canada. A building automation system will track real-world performance once residents move in, monitoring energy use to confirm the building lives up to its modelling. For residents who can least afford volatile utility bills, that quiet efficiency is its own form of care.
On the exterior, integrated metal screens designed by artist Leo Krukowski soften the building's presence on the street. Their patterns draw on Indigenous and naturalized plant species, rooting a technical, prefabricated building in the land and life around it. More than decoration, the screens give 1120 Ossington an identity distinct enough to belong on its street, rather than occupy it.
