ARCHIVED - 3.4.6.3.(1)

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3.4.6.3.(1)

Application

Intent

OS3


Objective	OS3 Safety in Use
Attribution	[F10-OS3.7]
Application	Application 1: Maximum vertical rise of stairs between floors or landings. This applies, in buildings described in Sentence 1.3.3.2.(1) of Division A to: interior and exterior exits, as stated in Appendix Note A-3.4.6. and exits serving floor areas that are intended for occupancy, including mezzanines as stated in Sentence 3.4.2.2.(1). Application 2: This also applies to: stairways used by the public as access to exits, as stated in Appendix Note A-3.4.6. tents and air-supported structures, as stated in Sentences 3.1.6.1.(1) and 9.10.1.2.(1), and stairs in a means of egress from a roof, where a roof is used or intended for an occupant load of more than 60, as stated in Sentence 3.3.1.3.(4), stairways, as stated in Sentence 3.3.1.14.(1), and platforms for fire escapes, as stated in Sentence 3.4.7.7.(1). Exceptions: except: exits in Group B, Division 2 occupancies, as stated in Sentence 3.1.6.2.(1), which prohibits air-supported structures from being located above the first storey on any building, as stated in Sentence 3.1.6.2.(2), which prohibits air-supported structures from being used for classrooms or for Groups B, C, or Group F, Division 1 major occupancies, as stated in Sentence 3.1.6.2.(3), which requires air-supported structures to be designed as open floor spaces without interior walls, mezzanines, intermediate floors or similar construction, as stated in Sentence 3.3.1.3.(5), which applies to rooftop enclosures, as stated in Sentence 3.3.1.14.(2), which applies to service rooms, service spaces and industrial occupancies, as stated in Sentence 3.3.4.7.(1), which applies to dwelling units, as stated in Sentence 3.4.2.2.(2), which applies to mezzanines that: are not required to terminate at a vertical fire separation [see Article 3.2.8.1.], are not intended for an occupant load more than 60, do not exceed the area limits for rooms and suites in Table 3.4.2.2., and have limited travel distances to egress doors or stairs, and as stated in Sentence 3.4.2.2.(3), which applies to at least half of the required means of egress from a mezzanine if the mezzanine is not required to terminate at a fire separation as permitted by Sentence 3.2.8.2.(1).
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Intent	Intent 1: To limit the probability that persons using exit stairs in a emergency situation will require a rest, or will develop a psychological fear of falling, which could lead to delays in the evacuation or movement of persons to a safe place, which could lead to harm to persons. Intent 2: To exempt exit stairs serving Group B, Division 2 occupancies from the requirements in the first part of Sentence 3.4.6.3.(1), which would otherwise permit a vertical rise of the stairs of up to 3.7 m, and limit the rise to not more than 2.4. m, on the basis that: occupants may be in a poor state of health and may need to rest more frequently, and staff moving patients may require intervals of resting.
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