BCAB #1844

March 5, 2020

Re: Doors in Exit Shafts for High Buildings

Project Description

The base building is multi-use, classified as Group A Division 2, Group C, and Group F Division 3, using Any Height, Any Area, Sprinklered construction criteria. The building exceeds 18 m in height measured from grade to the highest floor level, resulting in Subsection 3.2.6 Additional Requirements for High Buildings being applicable. 

There is an elevator lobby, approximately 1.9 m wide and 6.8 m long which runs off of, and perpendicular to, a public corridor. At the end of the elevator lobby is a doorway into an adjacent exit stair shaft. The door is approximately 914 mm x 2030 mm door, with a 90-minute Fire Protection Rating, which swings into the elevator lobby. The door is installed to comply with the requirements of Sentence 3.2.6.2.(3) to vent the stairway for smoke control. The door has no operational features that would limit its use for venting purposes only, as its configuration would allow building occupants to use the door for convenience on a day to day basis.

Applicable Code Requirements

Sentences 3.2.6.2.(1) to (3) and 3.4.4.4.(1) of Division B of the British Columbia Building Code 2018.

3.2.6.2. Limits to Smoke Movement

1) A building to which this Subsection applies shall be designed in accordance with Sentences (2) to (6) and Article 3.2.6.3. to limit the danger to occupants and firefighters from exposure to smoke in a building fire.

2) A building referred to in Sentence (1) shall be designed so that, during a period of 2 h after the start of a fire, each exit stair serving storeys below the lowest exit level will not contain more than 1% by volume of contaminated air from the fire floor, assuming an outdoor temperature equal to the January design temperature on a 2.5% basis determined in accordance with Subsection 1.1.3. (See Note A-3.2.6.2.(2).)

3) Each stairway that serves storeys above the lowest exit level shall have a vent to the outdoors, at or near the bottom of the stair shaft, that

a) has an openable area of 0.05 m² for every door between the stair shaft and a floor area, but not less than 1.8 m²,

b) opens directly to the outdoors or into a vestibule that has a similar opening to the outdoors, and

c) has a door or closure that

i) is openable manually, and

ii) can remain in the open position during a fire emergency.

(See Note A-3.2.6.2.(3).)

3.4.4.4. Integrity of Exits

1) A fire separation that separates an exit from the remainder of the building shall have no openings except for

a) standpipe and sprinkler piping,

b) electrical wires and cables, totally enclosed noncombustible raceways and noncombustible piping that serve only the exit,

c) openings required by the provisions of Subsection 3.2.6.,

d) exit doorways, and

e) wired glass and glass block permitted by Article 3.1.8.16.         

Decision being Appealed (Local Authority’s Position)

The local authority has determined the only doorways permitted to penetrate the fire separation between the exit and the remainder of the building are exit doorways, and the subject door must swing in the direction of exit travel. Further, the local authority does not consider the subject doorway to comply with the requirements for smoke control venting, as the configuration for venting to the outdoors is inadequate.

Appellant's Position

The appellant considers the subject doorway to be specifically permitted by Clause 3.4.4.1.(1)(c) as it is an opening in accordance with the provisions of Subsection 3.2.6.

Appeal Board Decision #1844

It is the determination of the Board that the subject doorway in its present configuration is not in conformance with the Building Code provisions cited and the Board upholds the local authority’s decision.

Notwithstanding, should the subject doorway be necessary to control smoke movement, and the design of the doorway is modified such that it’s use would be solely limited to the function of smoke venting in accordance with the provisions of Subsection 3.2.6., the Board would consider this to be compliant with the requirements of the Building Code.

Reason for Decision

The intent statement relating to Sentence 3.4.4.4.(1) indicates that the requirements of this Sentence supersedes the permissions granted in other areas of the Code for openings in exit fire separations and limits the openings to only certain penetrations on the basis of maintaining the integrity of exits. It has been identified in the Appeal application that the subject door could be used for other purposes, such as a convenience circulation route for occupants of the building. It is the opinion of the Board this would increase the risks associated in maintaining the integrity of the exit beyond those envisioned by Sentence 3.4.4.4.(1).

However, if the design of the subject doorway was modified to limit its use solely for the purpose of smoke venting for the provisions of Subsection 3.2.6., by means such as locking or alarming, this would then be considered Code compliant. This would need to be identified in the building’s required Fire Safety Plan.

The Board further notes:

“If a shaft does not have a direct opening to the exterior, alternative means must be provided to achieve smoke control. If a corridor or vestibule is used as a link between the exit level of an interior stair shaft and the outdoors to provide a venting system, it will be necessary to assess the reliability of the overall system”.

Lyle Kuhnert

Chair, Building Code Appeal Board