Changing Lanes: Passive Housing Prototype in Toronto Alley Showcases All-Wood Construction

It’s been just over a year since Toronto city council green-lit garden suites. Uptick has been slow, partially because the bylaw was initially challenged – the Ontario Land Tribunal eventually dismissed the appeal, but it took five months to do so. However, interest in building this property type remains high, similar to laneway housing. The latter (and catalyst for the garden suite) is a self-contained residential home generally smaller than the main house on the lot. It must be located next to a public alley, typically in the backyard, and is intended to function as a rental income property in an effort to help ease Toronto’s housing crisis.

Not long after the city approved laneway housing in 2018, the University of Toronto launched a pilot project based on a previously published study to bring these homes to its St. George campus. Three prototypes were designed by Baird Sampson Neuert (BSN) Architects to be net-zero for energy consumption and carbon emissions using passive house principles and all-wood construction. Completed in 2020, and serving as the vanguard for 40 laneway and infill homes, two of the prototypes can be found in a quiet alley near Robarts Library – a three-storey, two-bedroom plus study and two-storey, one-bedroom plus study approximating 890 and 760-square feet, respectively. They both accommodate a student family with children.

Architecturally, the laneway houses are conceived as a contemporary intervention that is sympathetic to the scale, massing, and context of the surrounding neighbourhood. They also create outdoor space for their occupants – a shared courtyard that functions as ‘backyard.’

Each home’s shell is comprised of super-insulated, prefabricated Build Smart E-Walls that were assembled on-site. The PH-certified wall panels (R-45) incorporate framing, structural sheathing (R-54), an air control layer, continuous exterior insulation, a weather-resistive barrier, factory-installed triple-glazed windows (R-7) and flashing, and a shallow super-insulated Geo-passive slab foundation system (R-24) in one lap around the building. Their use provided improved building envelope performance with less air leakage for improved occupant comfort; saved expense; resulted in major waste reductions and landfill usage since the materials are made to required dimensions; enabled a tighter construction schedule, reducing it by two months; and eliminated opportunities for errors.

The exterior features renewable, carbon-sequestering ash wood siding supplied by CFP Wood. Locally harvested and manufactured in Guelph, Ont., it has been thermally treated to dramatically improve hardness, rot/insect resistance and durability (transforming Durability Class DC- 3 to the highest DC1 – EN 350 durability standard). The cladding exhibits numerous grain patterns while displaying the natural beauty of its rich brown colour tones. Left to weather naturally, it will turn a beautiful patina grey.

Other project highlights include the addition of solar PV panels and earth tubes for pre-conditioning fresh air, enabling higher levels of ventilation for a healthier indoor environment. Interiors are brightly lit and have open-concept kitchen-living rooms and hardwood floors.

The Passive Laneway Housing Prototypes garnered a 2023 Ontario Wood Works! award. Presented May 2, the awards program honours the people and organizations that, through design excellence, advocacy, and innovation, are advancing the use of wood in all types of construction. The project team included BSN Architects, Local Impact Design (structural and mechanical engineer/passive house consultant), Index Construction (contractor), Kabinetry Design Studio, Richmond Laminate and CFP Wood (wood suppliers).

Clare Tattersall is an interior designer and decorator in Toronto, and the editor of Canada’s floor covering magazine, Coverings.