Single Stair Alternative Solutions
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 project explores how single stair design can help unlock more affordable, mid-sized housing in cities across the country. The approach uses space more efficiently, supports both new builds and renovations, and enables better layouts, accessibility, and sustainability. LGA Architectural Partners developed six prototype buildings and partnered with 10 architectural firms to launch pilot projects, test alternative solutions, and share knowledge to advance housing innovation.
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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Smarter Design for Better Housing
The single stair model is a safe, space-efficient solution for small apartment buildings. It reduces the building footprint, enables more flexible and accessible layouts, and makes it easier to add housing on smaller or irregular lots — helping to unlock affordable, family-friendly homes in more places.
A National Network of Real-World Testing
Ten architectural firms from across Canada adapted and applied the single stair approach to pilot projects in diverse contexts. Their work demonstrates how the model can be scaled and tailored to suit a variety of sites, housing needs, and building types.
Open Tools for Industry Adoption
The project website shares six fully developed building prototypes, along with detailed data from 10 pilot projects. These open-access resources support architects, developers, and municipalities in adapting the model to local conditions — helping accelerate adoption and drive housing innovation.
LGA’s Pilot Project
Location: Toronto
Typology: 3-Storey Apartment Building
Building Area: 357.4m2
Gross Floor Area: 1,072.2m2
Residential Unit Mix: 10 dwelling units – (5×2-Bed, 5×3-Bed)
This project transforms an existing residential lot in a downtown Toronto neighbourhood by replacing a pair of semi-detached houses with 10 affordable rental homes in a small apartment building. A building permit application and alternative solution have been submitted to the City of Toronto for this innovative single stair design. The building contains two units on the ground floor and four units on each of the upper floors, allowing each apartment to be on a corner of the building with more natural light and privacy for each bedroom. The design also includes an elevator to make the building fully accessible and features a central stair that is directly visible from the building entrance.
While zoning permits a row of stacked townhouses or a small apartment building on this site, developers often choose rowhouses because each unit has a private entrance and 100% of the building can be sold. But this project, led by a community land trust and non-market housing provider, prioritizes long-term, accessible rental housing.
By using a single stair and elevator, the project fits 10 units within the same height, lot coverage, and setback as a typical rowhouse development — proving that smarter design can make room for more inclusive, affordable homes in our city.
Single Stair Alternative Solutions is the recipient of:
”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.
Jury CommentRAIC Research & Innovation in Architecture Award 2025
Right: Copy of Canadian Architect Article – May 2025
