March 16, 2019
Re: Convergence of Exits
The project is a sprinklered 10-storey residential building of noncombustible construction. The building is served by two exit stairs. One stair discharges on the north face of the building and the other stair discharges on the east face of the building. Each exit leads to exterior paths which join on the east side and is then connected to a public thoroughfare on the south of the site. The exterior paths are approximately 1.4 m in width and include steps and are bounded by a retaining wall. The design confines the users to the path from the exit discharge to the public thoroughfare. The path is either more than 3 m from the building or is protected from fire exposure from the building.
Applicable Code Requirements
The definition of ‘exit’ in Division A and Sentence 22.214.171.124.(2) of Division B of the 2012 British Columbia Building Code.
Exit means that part of a means of egress, including doorways, that leads from the floor area it serves to a separate building, an open public thoroughfare, or an exterior open space protected from fire exposure from the building and having access to an open public thoroughfare. (See Appendix A.)
126.96.36.199.(1) Except as permitted by Sentence (2), if more than one exit is required from a floor area, each exit shall be separate from every other exit leading from that floor area.
188.8.131.52.(2) If more than 2 exits are provided from a floor area, exits are permitted to converge in conformance with Sentence 184.108.40.206.(2), provided the cumulative capacity of the converging exits does not contribute more than 50% of the total required exit width for the floor area.
Decision being Appealed (Local Authority’s Position)
The local authority has determined that the means of egress design indicates a convergence of exits and Sentence 220.127.116.11.(2) only permits a convergence of exits when there are more than two exits. The local authority considers the paths to be part of the exit.
The appellant maintains that Sentence 18.104.22.168.(2) does not apply as the paths at the point where they join is not a component of an exit as defined in the Code.
At the point where they join, they are in an exterior open space that is protected from fire exposure from the building and has access to an open public thoroughfare. The exterior open space is protected from fire exposure from the building as the path is more than 3 m away from any unprotected openings in the building, which meets the requirements of the exterior open space in the definition of exit.
Appeal Board Decision # 1825
It is the determination of the Board that path from the point where the two exterior paths join to the public thoroughfare is not part of the exit and that the limits on convergence in Sentences 22.214.171.124.(1) and (2) are not applicable.
Reason for Decision
The Board considered the question of what constitutes an exterior open space in the definition of “exit”. The Board referred to the NRC-CNRC “User’s Guide 1995 – NBC 1995 Fire Protection, Occupant Safety and Accessibility (Part 3)” which states “The question of what constitutes a safe open space is often asked. Typically, this would be specific to the design being considered and is based on an evaluation of egress from the space, the construction of an adjacent building, the separation of the building from the space, and the presence of other hazards.” Although the Board acknowledged that occupants are confined to the path, it considered the characteristics of this building and determined the path to be in an exterior open space protected from fire exposure from the building and the path provides the access to an open public thoroughfare. The Board’s decision is further premised on the assumption that there are no fire exposure conditions from the basement parking garage that may impact the subject exterior open space.
Chair, Building Code Appeal Board