(1) Exit stairs that serve interconnected floor spaces as provided in Articles 3.2.8.3. to 3.2.8.11. shall conform to the requirements in Article 3.2.8.4. and in this Section.
Div. B › Part 3 › 3.4 › 3.4.3 —
Width and Height of Exits
Related (referenced by this article)
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(1) In a building that is more than 18 m in height, measured between grade and the floor level of the top storey, an emergency power supply capable of operating under a full load for at least 2 h shall be provided by an emergency generator or by a separate service not supplied by the same substation as the primary source for fans required for smoke control purposes in Articles 3.2.8.4., 3.2.8.5., 3.2.8.6. and 3.2.8.9.
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(1) The systems for smoke control and venting described in Articles 3.2.8.4., 3.2.8.5., 3.2.8.6. and 3.2.8.9. shall be tested to ensure satisfactory operation.
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(1) In buildings constructed in conformance with Articles 3.2.8.4. to 3.2.8.11., the unprotected openings through floor assemblies in an interconnected floor space shall be of sufficient size and shall be positioned relative to each other so as to be capable of containing, within the full height of the interconnected floor space, a cylinder conforming to Sentence (2). (2) The cylinder referred to in Sentence (1) shall have a cross-section that, where taken at a right angle to the longitudinal axis of such cylinder, is, (a) a circle at least 9 m in diameter, or (b) an ellipse at least 7 m wide along the minor axis and at least 65 m2 in area.
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(1) A building that is more than 18 m in height, measured between grade and the floor level of the top storey, and that contains an interconnected floor space, shall be designed to limit the passage of smoke from a fire into exit stairshafts opening into an interconnected floor space so that during a 2 h period after the start of fire, such stairshafts 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. (2) Where a building containing an interconnected floor space is more than 75 m in height, measured between grade and the floor level of the top storey, the exit stairshaft protection required in Sentence (1) shall be accomplished by the provision, between each floor area and each exit stairshaft, of a vestibule provided with a mechanical air supply or with a vent opening to the outdoors. (3) Where a vestibule protecting an exit stairshaft is incorporated into the design of the building to meet the requirements of Sentence (1) or (2), such vestibule shall, (a) be designed so that each doorway for a door opening into the vestibule is located at least 1 800 mm from a door or doors opening outward from the vestibule, (b) be separated from the remainder of the floor area by a fire separation having a fire-resistance rating at least equal to that required for the exit that it serves except that the fire-resistance rating of a fire separation between the vestibule and a public corridor need not exceed 45 min, and (c) not have a door or doors opening into more than one exit stairshaft. (4) Except where exits serving the floor area are at ground level, the increased travel distance to exits permitted by Clause 3.4.2.5. (1)(c) shall not apply to a floor area within an interconnected floor space. (5) Where a portion of a floor area is not within an interconnected floor space, required access to exit from such portion of a floor area shall not lead through an interconnected floor space. (6) Except as provided in Sentences (7) and (8), portions of an interconnected floor space that have floor levels more than 18 m above grade shall be served by exits that provide at least 0.3 m2 of area of treads, landings and floor surface for each occupant of such portions of an interconnected floor space. (7) The requirements of Sentence (6) need not be applied where a floor area that is a portion of an interconnected floor space and that has a floor level more than 18 m above grade is separated from the remainder of the interconnected floor space by a fire separation having a fire-resistance rating of at least 1 h, except that no fire-resistance rating is required for such fire separation where all of the major occupancies contained within the interconnected floor space may be classified as light hazard occupancies in conformance with Appendix A of NFPA 13 “Installation of Sprinkler Systems”. (8) The requirements of Sentence (6) need not be applied where the exit stairs that serve interconnected floor spaces are designed so that the required width of each stair is cumulative.
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(1) Except as provided in Sentence (2), where an elevator shaft opens into an interconnected floor space and into storeys that are above such space and that have floor levels more than 18 m above grade, either the elevator doors opening into the interconnected floor space or the elevator doors opening into the storeys above the interconnected floor space shall be protected by vestibules that, (a) are designed to restrict the passage of contaminated air to the limit described in Sentence 3.2.8.4. (1), and (b) conform to the requirements of Sentence 3.2.8.4. (3). (2) Where elevator doors opening into an interconnected floor space are protected by vestibules in conformance with Sentence (1), the elevator doors opening into the lowest storey of the interconnected floor space need not be protected by such vestibules.
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(1) Openings provided for access between an interconnected floor space and a building or a portion of a building containing Group B major occupancy sleeping rooms shall be provided with vestibules that are provided with a mechanical air supply and that are designed, (a) to restrict the passage of smoke from the interconnected floor space into the area containing sleeping rooms in accordance with the limits described in Sentence 3.2.8.4. (1), and (b) in conformance with Clause 3.2.8.4. (3)(a).
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(1) In a building containing an interconnected floor space, storeys that are wholly or partially within an interconnected floor space and all storeys below an interconnected floor space shall be sprinklered. (2) In a building containing an interconnected floor space, (a) waterflow alarm signals from sprinkler systems shall be transmitted to the fire department in conformance with Sentence 3.2.4.8. (4), and (b) sprinkler systems shall be electrically supervised as required by Sentence 3.2.4.10. (3).
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(1) A building containing an interconnected floor space shall be provided with, (a) a fire alarm system and electrically supervised annunciator conforming to Subsection 3.2.4., (b) a system of smoke detectors located, (i) on the ceiling of each storey in the vicinity of the openings through floor assemblies described in Article 3.2.8.3., except within dwelling units, heat detectors may be installed instead of smoke detectors, and (ii) as required for the activation of the smoke control system described in Sentences 3.2.8.9. (3), (4), (6) and (7), and (c) facilities for transmitting a signal to the fire department in conformance with Article 3.2.4.8.
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(1) A smoke control system conforming to Sentences (2) to (8) shall be designed to control the movement of smoke within a building containing an interconnected floor space. (2) The design of the smoke control system shall assume an outdoor temperature equal to the January design temperature on a 2.5% basis. (3) Upon activation of the sprinkler system or automatic detection of smoke by at least two smoke detectors in a single zone within an interconnected floor space, the system shall, (a) stop air moving fans that provide for the normal exhausting or re-circulating of air in an interconnected floor space, (b) activate exit stairshaft protection required in Article 3.2.8.4., (c) activate elevator protection required in Article 3.2.8.5., and (d) activate the vestibule air supply required in Sentence 3.2.8.6. (1). (4) A building containing an interconnected floor space may be designed so that, in the event of a fire arising in a floor area or part of a floor area within the interconnected floor space, automatic detection of such fire will activate air handling equipment that, (a) extracts air directly from such floor area or part of a floor area at the rate of at least six air changes per hour, and (b) supplies air in sufficient quantities and at appropriate locations to prevent smoke from passing out of such floor area into other portions of the interconnected floor space. (5) For purposes of Sentences (6) and (7), the volume of an interconnected floor space need not include the aggregate volume of those floor areas or portions of floor areas designed to have zoned air extraction in accordance with Sentence (4). (6) A mechanical exhaust shall be provided to remove air at the top of an interconnected floor space at the rate of at least six air changes per hour, except that where the volume of the interconnected floor space exceeds 17 000 m3, only four air changes per hour need be provided. (7) Except where zoned mechanical exhaust described in Sentence (4) has been activated, upon automatic detection of smoke within the volume of the interconnected floor space, the mechanical exhaust described in Sentence (6) shall be automatically activated and supply air shall be provided in sufficient quantity and at appropriate locations to allow a consistent rate of removal of smoke throughout the volume of the interconnected floor space. (8) Overriding manual controls for the smoke control system shall be provided for fire department use at an acceptable location in the vicinity of the fire alarm annunciator.