CCR 1816

Part 3 – Single egress for multi-unit residential buildings up to 6 storeys

This request for change proposes additional sentences under NBC Div.B Section 3.4.2.1 to introduce single exit multi-unit residential buildings of up to six storeys, requiring additional life safety measures and placing limits on the occupant load and number of dwelling units per storey served by the single exit.

CCR 1815

Part 9 – Single egress for multi-unit residential buildings up to 3 storeys

Proponent

Conrad Speckert
LGA Architectural Partners

David Hine
David Hine Engineering Inc.

Submitted

2022-04-18 (resubmitted 2025-03-08)

Code Reference(s)

NBC Div. B – 3.4.2.1

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What is the problem?

The requirement for two means of egress in multi-unit residential buildings exceeding two storeys may be an outdated condition of pre-modern fire safety practices in combustible construction. The National Building Code of Canada is inconsistent with (and does not allow for the same design flexibility as) building codes in other jurisdictions and fails to recognize that a second egress may be unnecessary for “missing middle” and mid-rise housing typologies where other life safety measures are provided.

By prohibiting single egress designs at this scale, the National Building Code limits the feasibility of buildings that are between low-rise single-family homes and high-rise apartment buildings. Making it difficult to build multiplexes and small apartment buildings prevents urban areas from developing more sustainable growth and increasing the balanced supply of more diverse housing options.

This code change request recognizes that the requirement for two means of egress is appropriate for larger buildings and non-residential occupancies. However, requiring a second egress is a prohibitive burden for smaller multi-unit residential projects, whereas one exit is permitted in many other jurisdictions.

• The United States model building (2021 International Building Code) allows a single exit for R-2 (apartment building) occupancies in sprinklered buildings of up to 3 storeys in height, with a maximum of 4 dwelling units per storey. The NFPA 101 and 5000 model codes allow a single exit for R-2 (apartment building) occupancies in sprinklered buildings of up to 4 storeys in height, with a maximum of 4 dwelling units per storey.

• The City of Seattle (SBC 2018: 1006.3.3.7 Single Exits) allows a single exit for R-2 occupancies in sprinklered buildings of up to 6 storeys in height, with a maximum of 4 dwelling units per storey and several additional conditions. New York City allows up to 6 storeys with a maximum floor area per storey (NYC Building Code 2014: 1021.2.5 Single Exits) and additional conditions.
  

• Australia (NCC 2015 Vol. 1: D1.2) allows a single exit for apartment buildings up to 25m in height. New Zealand (C/AS2 - 3.13.1.) allows a single exit for apartment buildings up to 25m in height if the building is sprinklered, and up to 10m in height if the building is not sprinklered.
  

• The United Kingdom (Building Regulations 2010 – Fire Safety: Approved Document B) did not previously establish a maximum building height for single exit residential buildings. In response to the Grenfell Tower inquiry, the Royal Institute of British Architects (RIBA) and London Fire Brigade requested further study of the risks associated with high-rise residential buildings with a single exit stair. The 2026 amendments to Approved Document B establish a maximum building height of 18m for single exit apartment buildings.
  

This code change request falls within several of the CCBFC’s strategic technical and policy priorities as a select fire and life safety topic and as a targeted topic. Accessibility is also addressed in terms of egressibility, the proposed life safety measures improve the protection and fire safety for disabled occupants remaining in their suite during an emergency. Single egress also indirectly addresses the priorities of climate change mitigation and adaptation, and energy-efficiency, given the improved building form factor, design flexibility for passive ventilation and daylighting, and the sustainable urban development benefit of single stair buildings.

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Impact Analysis: What are the cost/benefit implications?

The benefits in efficiency, cost and improved livability for a single egress building significantly outweigh the cost of the additional life safety measures. The requested change offers the measurable benefit of increased floor area efficiency and reduced hard construction costs for “missing middle” and mid-rise housing types, as well as making such buildings feasible on smaller properties.

The requested change also has additional benefits for the environmental, spatial, and social quality of multi-unit residential buildings, such benefits include:

• making it easier for dwelling units to receive natural daylight from both sides as “through units”,

• allowing for cross-ventilated dwelling units rather than the deep, single-orientation layouts typical of double-loaded corridor buildings requiring two means of egress,

• balancing the exposure of each dwelling unit to urban and traffic noise, such that bedrooms can be placed on the quiet side and living areas along the street facing side of the building,

• making it easier to design larger, family-oriented dwelling units with three to four bedrooms, and

• improving the sense of community and social interaction in an apartment building by decreasing the number of dwelling units sharing an exit.

The requested change does not result in additional costs compared to buildings adhering to the existing acceptable solutions requirement for two means of egress. The requested change enables the alternative of a single stair design, with limitations on the building size and requirements for additional life safety measures to compensate for providing one exit. This additional design flexibility may be cost neutral or, in some cases, lead to cost savings. It may also bring buildings back into feasibility on smaller sites where the lot size does not accommodate a design complying with the second egress requirement.

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What are the enforcement implications?

The requested change can be enforced within the current enforcement framework of design review and permit approvals, as well as the administrative requirements for evacuation plans.

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Other Comments

This code change request is being submitted in response to the official correspondence on March 31, 2022, from the Ontario MMAH (Ministry of Municipal Affairs and Housing) requesting the CCBFC to prioritize a code change to allow for “a single means of egress in some residential buildings as a Building Code change that could enable the construction of more gentle density and multi-unit housing.”

In January 2022, several architects, planners and developers co-signed a letter sent to the Ontario Housing Affordability Task Force recommending a building code change to “permit residential buildings of up to six storeys with a single exit stair” with additional life safety measures.

This code change request has been prepared by Conrad Speckert, an intern architect at LGA Architectural Partners with the support of building code expert David Hine of David Hine Engineering. The code change request and related research is funded by the DIALOG Architects 2021 Michael Evamy Scholarship and a CMHC-SSHRC Collaborative Housing Research Network, Balanced Supply of Housing Node grant under the supervision of Prof. Nik Luka at McGill University.

Since the original submission of the CCR in April 2022, several US and Canadian jurisdictions have initiated studies and changes to address single exit stair (SES) building design. Several architects and building code consultants across Canada have also developed alternative solution proposals for small multi-unit residential buildings served by a single exit stair for up to 3 to 6 storeys in height.

The proponent is willing to provide a presentation and is willing to provide additional supporting documentation and information.

Supporting Documentation:

1. “Small Single-Stairway Apartment Buildings Have Strong Safety Record.” Pew Trust. February 27, 2025.
   
   
2. “Potential to Update the Vancouver Building Bylaw to Enable Single Egress Stairs.” City of Vancouver. February 26, 2025
   
   
3. “The Seattle Special: A US City’s Unique Approach to Small Infill Lots.” Mercatus Center. December 2, 2024.
   
   
4. “Legalizing Mid-Rise Single-Stair Housing in Massachusetts.” Joint Center for Housing Studies, Harvard University. October 10, 2024.
   
   
5. NFPA Single Exit Stair Symposium. (Various articles, reports and presentations).
   
   
6. “Housing Solutions Lost in Translation without a National Fire Administration.” CAFC. August 2024.
   
   
7. “Evaluating Stakeholder Concerns About Proposed Single Egress Stairs.” University of the Fraser Valley. July 2024.
   
   
8. “Single Exit Stair: Ontario Building Code Feasibility Study”. LMDG Building Code Consultants. July 2024
   
   
9. “Single Egress Stair Building Designs: Policy and Technical Options Report, British Columbia.” Jensen Hughes. June 2024.
   
   
10. “Point Access Block Building Design: Options for Building More Single-Stair Apartment Buildings in North America.” Cityscape. March 2024.
    
    
11. “BC Housing Single Stair Report.” PUBLIC Architecture. February 2024
    
    
12. “OAFC Position on Single Exits in Buildings up to Six Stories or that Exceed Current Code Requirements.” OAFC. January 9, 2024.
     
    
13. Jurisdictional Scan: Maximum Allowable Building Height with Single Egress for Multi-Unit Residential Occupancies. April 2022. Prepared by proponent. (refer to most recent version at www.secondegress.ca)
    
    
14. Case Study Plans: Examples of Single Exit Stair Multi-unit Residential Buildings in other Jurisdictions. April 2022. Prepared by proponent.
    
    
15. “Ontario MMAH – Single Egress.” Correspondence with CCBFC. March 31, 2022.
    
    
16. “Re: Building Code Change to Enable Single Stair Residential Buildings up to Six Storeys.” Letter to the Ontario Housing Affordability Task Force. January 27, 2022.
    

References (Original Submission in April 2022):

Booth, R. (2022). “Rethink for skyscraper near Grenfell site with single fire escape staircase.” The Guardian.

Bukowski, R. and Kuligowski, E. (2004), The Basis for Egress Provisions in U.S. Building Codes, Interflam.

Bukowski, R. (2009). Emergency Egress from Buildings. NIST Technical Note 1623. U.S. Department of Commerce: National Institute of Standards and Technology.

Calder, K. et al. (2015). The Historical Development of the Building Size Limits in the National Building Code of Canada. The Canadian Wood Council / Sereca Consulting Inc.

Calder, K., and Senez, P. (2016). The Key Modes of Fire Spread in Wood-Framed Apartment Buildings – A Canadian Perspective. World Conference on Timber Engineering.

Clare, J. and Kelly, H. (2017). Fire and at risk populations in Canada - Analysis of the Canadian National Fire Information Database. 

Eliason, M. (2021). “The Case for More Single Stair Buildings in the US,” Treehugger Magazine

Eliason, M. (2021). “Seattle’s Lead on Single Stair Buildings.” The Urbanist.

Eliason, M. (2021). “Unlocking livable, resilient, decarbonized housing with Point Access Blocks,” City of Vancouver.

FEMA. (2011). Fire Death Rate Trends: An International Perspective. U.S. Fire Administration National Fire Data Center, Topical Fire Report Series, Vol 12, Issue 8.

Garis, L., Clare, J. (2016). “Life Safety Systems, Fire Department Intervention, and Residential Fire Outcomes. Analysis of 28 Years of BC Fire Incident Reports: 1988-2015.” University of the Fraser Valley, Centre for Public Safety and Criminal Justice Research.

Garis, L. et al. (2018). “Sprinkler Systems and Residential Structure Fires – Revisited: Exploring the Impact of Sprinklers for Life Safety and Fire Spread.” University of the Fraser Valley, Centre for Public Safety and Criminal Justice Research.

Garis, L. et al. (2019). “Fire Protection System​(s) Performance in the Residential Building Environment: Examining the Relationship between Civilian and Firefighter Injuries: A Retrospective Evaluation of Residential and Residential Apartment Fires, 2005 to 2015.” University of the Fraser Valley, Centre for Public Safety and Criminal Justice Research.

Garis, L., Clare. J. (2020). “Is taller safer? A closer look at the impact of building height and life safety systems.” Firefighting in Canada.

Grabar, H. (2021). “The Single-Staircase Radicals Have a Good Point,” Slate Magazine.

HM Government. (2006). Fire Safety Risk Assessment: Sleeping Accomodation.

Proulx, G. (2001). Occupant Behaviour and Evacuation. NRC Publications Archive. NRCC-44983.

Ontario Association of Architects. (2019). Housing Affordability in Growing Urban Areas. SvN Architects + Planners.

Royal Institute of British Architects. (2022). RIBA fire safety policy note – February 2022.

Senez, P. et al. (2008). A Historical Perspective on Building Heights and Areas in the British Columbia Building Code (Senez Reed Calder Historical Report).

Stock, B., Wallasch, K. (2020). Fire Safety Requirements for High-Rise Residential Towers in England and Germany. FeuerTrutz International 2020.

Stock, B., Wallasch, K. (2009). Single living. Fire & Risk Management (F&RM) Journal, 19.

Winberg, D. (2016). International Fire Death Rate Trends. SP Technical Research Institute of Sweden.

Wu, S. (2001). The Fire Safety Design of Apartment Buildings. Fire Engineering Research Report 01/10. University of Canterbury School of Engineering.

Zheng, A. et al. (2022). Fire Severity Outcome Comparison of Apartment Buildings Constructed from Combustible and Non-combustible Materials. University of the Fraser Valley, Centre for Public Safety and Criminal Justice Research.

Zimmerman, F. (2010). Breaking Up with the Double Loaded Corridor: A Study of Progressive Housing Design and it’s Influence on Social Networks.

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