CMHC Housing Supply Challenge
Round 4: Building for the Future

Single Stair Alternative Solutions

Design Innovation for Middle Housing


Prescriptive building codes across Canada require two means of egress for any multi-unit residential building exceeding two storeys. However, a review of codes across other jurisdictions shows that multiplexes and small apartment buildings can be safely constructed with a single exit stair. This approach supports gentle density, maximizing land use on small sites while improving sustainability, accessibility and design flexibility.

Single exit stair (SES) building design adds enough floor area for at least another bedroom on each storey of a building and improves the feasibility of infill housing on small properties. The solution also allows for apartment layouts with more natural light and fresh air, as well as making it easier to provide an elevator to make three-storey buildings fully accessible.

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April 2025 - This research project is awarded The RAIC Research & Innovation in Architecture Award by the Royal Architectural Institute of Canada, and was featured in Canadian Architect magazine.

Jury Comments: “This meticulous study of single exit stair building code reform presents a transformative approach to addressing Canada's housing challenges. Through richly documented research and elegant visual presentation, the project demonstrates a comprehensive understanding of current barriers to housing supply. Working at the system level, this initiative promises far-reaching impacts on missing middle housing morphology across Canada. The thorough analysis and detailed solutions position this work to meaningfully influence future building codes.”

March 2025 - The Canadian Urban Institute hosted a series of “Single Stair Sessions” bringing together architects, engineers and building code experts to explore how alternative building code compliance can expand housing options in urban areas (Click on links below for Zoom Recordings):

March 18: Single Stair Sessions, Day 1 – Pilot Projects and Prototypes

March 19: Single Stair Sessions, Day 2 – Safety And Sustainability

March 20: CityTalk - Addressing Canada’s Housing Supply: Can Regulations Drive Housing Innovation?

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