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Evaluating travel distance provisions in the National Building Code of Canada: history, assumptions, current practices, and recommendations for future directions

From National Research Council Canada

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DOIResolve DOI: https://doi.org/10.4224/40003897
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EditorSearch for: Rodrigues, Justine; Search for: Van Boxmeer, Erika; Search for: Chan, Virginia; Search for: Ajweh, Ziad; Search for: Seward, Ulrik; Search for: Kinateder, Max1ORCID identifier: https://orcid.org/0000-0002-1669-3900; Search for: Potvin, Brigitte1; Search for: Robbins, Amanda1; Search for: Bwalya, Alex1; Search for: Zhao, Linbo1; Search for: Benichou, Noureddine1ORCID identifier: https://orcid.org/0000-0002-8878-2283
Affiliation
  1. National Research Council Canada. Construction
FormatText, Technical Report
Physical description163 p.
Subjecttravel distance assumptions; travel distance history; travel distance requirements; safe egress; national building code
Abstract
Commissioned under the National Research Council of Canada (NRC), this report reviews how the National Building Code of Canada (NBC) 2020 Part 3 travel distance provisions (Sentence 3.4.2.5.(1), maximum allowable distance to an exit in an emergency and related egress rules) are currently applied, what assumptions underlie them, and where clarifications would improve consistent use. The report does not evaluate enforcement or maintenance practices, expand definitions, or propose code text; priority is to clarify existing provisions and identify research needs to help inform potential future technical work by the relevant committees. Canada’s travel distance benchmarks, set in 1941–1965, remain virtually unchanged aside from minor updates. These limits were based on precedent and engineering judgment, not on empirical modelling, and reflect conditions from nearly a century ago (see Section 5). Given today’s larger, more complex buildings and diverse occupants, these prescriptive limits may no longer consistently reflect safety needs. The prescriptive travel-distance limits and related egress provisions are summarized in Section 4 of this report. It includes the objectives and functions; how distance interacts with endpoints, tenability, and vertical travel; and practical dependencies (sprinklers, smoke control/pressurization, emergency lighting, signage, wayfinding). Section 6 translates these themes into reviewable criteria, explicit tenability thresholds (see Table 3), declared system dependencies with degradation checks, visibility/wayfinding under smoke, and clear endpoints, used to demonstrate that Available Safe Egress Time (ASET) exceeds Required Safe Egress Time (RSET) to the declared endpoint. Code users noted (Section 7) that prescriptive distances work in typical buildings but fail in large or complex layouts. Participants asked for a clearer performance pathway tied to explicit tenability benchmarks, RSET inputs that reflect occupant diversity, and declared/tested dependencies. A hybrid model, prescriptive baselines with a structured performance pathway, would improve clarity, consistency, and safety across Canada.
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PublisherNational Research Council of Canada
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LanguageEnglish
Peer reviewedYes
Identifier978-0-660-79056-5
NR24-136/2025E-PDF
25-0045707-CRV-35876
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Record identifier9d649fd5-76a6-4e28-9ba7-49c34585cdbc
Record created2025-11-25
Record modified2025-11-26
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