mcCallumSather has completed 1120 Ossington Avenue, a new supportive housing development in Toronto providing 25 permanent rent-geared-to-income homes for people exiting chronic homelessness. Developed for non-profit housing provider St. Clare’s Housing, the three-storey building demonstrates an alternative approach to affordable housing construction.

Infill housing on an existing site

The building occupies a surplus portion of land beside an existing church that had previously been converted into supportive housing. The infill project increases the number of affordable homes on the site without expanding the urban footprint or requiring new infrastructure. Located directly on a transit line, the site also provides residents with access to public transport.

The simple L-shaped building responds to the scale, materials, and tones of the neighbouring church while maintaining a contemporary architectural expression.

Smart Density developed the original design, with municipal site plan approval already secured when mcCallumSather joined the project as architect of record. The overall building form, footprint, and exterior design had therefore been established, leaving mcCallumSather to complete the technical design, coordinate consultants, and prepare the project for construction within the existing constraints.

Mass timber and prefabrication

Many building components were manufactured off site before being delivered for assembly. The structural frame and enclosure were erected in just 17 days using three-ply cross-laminated timber (CLT) panels, CNC-fabricated by Element5 from Ontario-sourced wood and tilted into position on the narrow infill site.

The panelised construction system reduced the amount of work required on site, helping limit construction time, material waste, and disruption to the surrounding neighbourhood. Prefabrication also required a high degree of coordination during the design and fabrication stages, as many construction decisions were effectively made before components arrived on site.

Energy performance

The project was designed to exceed the energy performance requirements of the Canada Mortgage and Housing Corporation’s Rapid Housing Initiative. It combines an R-40 nominal building envelope, a Passive House-rated slab assembly, and energy-efficient mechanical systems. Energy modelling indicates performance approximately 40 percent better than the National Energy Code for Buildings baseline, with a building automation system in place to monitor energy demand and overall energy use during operation.

Responding to site and resident needs

The confined urban site required construction to proceed in stages. The rear portion of the building was assembled first to accommodate crane operations before work continued at the front of the property.

During construction, one interior wall was modified to provide approximately three inches of additional clearance in the kitchenette, allowing the units to meet accessibility requirements without affecting the overall layout.

Each self-contained unit includes a kitchenette and private bathroom, while shared indoor spaces support community programming and resident services. Accessibility was integrated into the planning to accommodate residents with a range of needs. Integrated metal screens designed by artist Leo Krukowski reference Indigenous and naturalised plant species and contribute to the building’s streetscape.

1120 Ossington combines mass timber, prefabricated construction, an efficient foundation and enclosure strategy, and operational energy measures to deliver permanent supportive housing within the constraints of a compact urban site.