The purpose of this report is to document findings and provide recommendations for the design of buildings containing a residential occupancy that are served by a single exit stair (SES). Section 2 of the report provides recommendations for buildings designed to Part 3 of the 2020 National Building Code of Canada. Specific discussion of smaller buildings designed in accordance with Part 9 of the NBC (not more than three storeys in building height and not more than 600m² in building area) are included in Section 3 of the report.

The recommendations contained within this report are based on:

• The provisions related to SES building design in other jurisdictions compared to the Canadian context.
• Egress analysis of SES building prototypes produced by LGA Architectural Partners compared to residential buildings permitted to be designed per the Division B acceptable solutions of the NBC.
• A retrospective analysis on the provisions of the NBC as fire science and technology has advanced.
• A review of sprinkler reliability and associated fire data for sprinklered residential buildings.
• A review of appropriate smoke protection measures.

This report is intended for information purposes only as a resource for qualified professionals to develop alternative solutions for SES building designs using objective-based building code compliance.


Click here to download the full report (March 2025)

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Established the background, scope, and methodology for this report. Discussion on the NBC 2020 acceptable solution of Sentence 3.4.2.1.(1). Discussion on intent statements, objective statements, and functional statements. Discussion on risk through the hierarchy of controls. High-level discussion on two methodologies of risk analysis through NFPA 550 and NFPA 551, respectively. High-level discussion of a semi-quantitative analysis as an example. Support for an inclusion of a risk analysis in for an SES alternative solution. The goal of the risk analysis is to compare a proposed SES building to a two-stair building meeting the relevant acceptable solutions.

Compared prescriptive building code requirements between several jurisdictions that permit the design and construction of SES buildings and provided recommendations to support SES alternative solutions within the context of the NBC for Part 3 buildings. The goal of this section is to take into account what other jurisdictions require to permit SES buildings, translate those building code provisions into an NBC context, and finally make recommendations for technical design options that provide an acceptable level of fire and life safety. 

Provided recommendations to support SES alternative solutions for Part 9 by comparing the level of performance of the acceptable solutions prescribed by relevant Division B criteria for buildings that fall under Division A, Article 1.3.3.3. The goal of this section is to build upon the ideas within Section 2 by translating the Part 3 suggestions for SES building design into the Part 9 context. 

Compared egress time between six prototype residential SES building designs and the maximum permitted size, two exit buildings of the same height and classification as permitted by the acceptable solutions prescribed by Division B.

Provided a retrospective analysis of the Building Code provisions when comparing the NBC 1980 and NBC 2020, which highlighted the fact that many of the current building code provisions provide a higher level of performance than their NBC 1980 counterparts and thus provide a higher general level of performance as it relates to fire and life safety for buildings. The goal of this section is to highlight that while the NBC 2020 now provides for much higher level of performance for fire and life safety, the single exit limits remain as they were in the NBC 1980.

Discussion on an annual study completed by the NFPA regarding fire statistics and the effectiveness of sprinklers in buildings in the United States. This section reiterates the findings of the NFPA study and to make the case that relevant fire statistics, if stratified, would help to support a risk analysis in which a residential building designed under the NBC 2020 Division B acceptable solutions is compared to a SES building with the features discussed in this report. 

Discussion on the provision of smoke control or smoke protection measures for SES buildings and why the application of Subsection 3.2.6. may not be appropriate. Options are provided for addressing the smoke protection of the means of egress. The goal of this section is to properly contextualize the rationale for smoke control in buildings and recommend technical design options for smoke protection measures for SES buildings up to six storeys in building height.

Discussion on the review and approval process of an alternative solution from the perspective of the Authority Having Jurisdiction and support the use of the peer review process for innovative alternative solutions such as for SES. 

Recommendations for future study into topics related to SES buildings. The goal of this section is to state the limitations of this report and to help guide future research on this topic.

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