§ 27-370 Exit passageways.
AC § 27-370
Exit passageways shall be maintained free of obstructions at all times. Not more than fifty percent of the total number of vertical exits provided for a building may be served by a single exit passageway, except as provided in subdivision (h) of section 27-370 of this article.
(a)Capacity. The capacity of exit passageways shall be as listed in table 6-1.
(b)Width. The width of an exit passageway serving one vertical exit shall be equal to the width of the vertical exit. The width of an exit passageway serving two or more vertical exits shall be equal to seventy-five percent of the width of all of the vertical exits that it serves. Width shall be measured in the clear between the narrowest points at any projections such as radiators, door swings, or pilasters.
(c)Height. Exit passageways shall have a clear height of seven feet six inches for at least seventy-five per cent of the floor area, with no point less than seven feet in height. No projection below the ceiling shall be located so as to obstruct full view of exit signs.
(d)Changes in level. Changes in level requiring less than two risers in an exit passageway shall be by a ramp complying with section 27-377 of this article. Risers and treads shall comply with the requirements of subdivision (e) of section 27-375 of this article.
(e)Construction. The construction of exit passageways shall be as required by table 3-4 for the applicable construction class of the building.
(f)Openings. No openings other than exit doors shall be permitted in exit passageways, except as provided in subdivision (h) of this section.
(g)Interior finish. The interior finish of exit passageways shall be in accordance with the requirements of table 5-4.
(h)Street floor lobbies. Street floor lobbies may be used as exit passageways when they comply with the requirements of subdivisions (a) through (g) of this section subject to the following modifications: (1) VERTICAL EXITS SERVED. One hundred per cent of the total number of vertical exits provided for a building may be served by a street floor lobby, if egress is provided in two different directions from the discharge points of all vertical exits to open exterior spaces that are remote from each other.
(2)WIDTH. Street floor lobbies serving as exit passageways shall be increased in width to accommodate the occupant load of all communicating spaces on the lobby floor that exit through them. The capacity per unit of width shall be as listed in table 6-1.
(3)OPENINGS. Openings between street floor lobbies serving as exit passageways and elevators or communicating spaces shall comply with the following: a. Doors.
1.Doors to stairways and elevators, and unsprinklered communicating spaces classified in occupancy group B-2, D-2, F-1 or F-2 shall be self-closing fire doors having a one and one-half hour fire protection rating.
2.Doors to unsprinklered communicating spaces classified in occupancy group G, H or J, or sprinklered communicating spaces classified in occupancy group B-2, D-2, F-1 or F-2 may be either: (a) self-closing fire doors having a three-quarter hour fire protection rating, or (b) glass or other noncombustible doors installed in conjunction with automatic fire doors having a one and one-half hour fire protection rating, with sprinkler heads installed over the doors on the room side.
3.No other door openings shall be authorized except as otherwise provided in this section. b. Other openings. Other openings to spaces classified in occupancy group C, E, F, G, H or J shall be permitted, provided they have a maximum length of eight feet and a maximum height of eight feet, are glazed by one-quarter inch polished plate glass or equivalent and are protected by automatic fire doors having a one and one-half hour fire protection rating and by automatic sprinklers complying with the construction requirements of subchapter seventeen of this chapter over the openings on the room side. c. Separations and limitations. Openings permitted by subparagraphs a and b of this paragraph shall not exceed in total length fifty per cent of the length of such enclosure wall except where the length of such wall is less than sixteen feet. Adjoining openings shall be separated from each other a minimum of three feet by construction having a two hour fire-resistance rating. d. Notwithstanding the restrictions in subparagraphs a, b, and c of this paragraph, the following openings may be authorized: 1. A space classified in occupancy group C, E, F-3 or, F-4 within fire separations having a minimum fire-resistance rating of one hour, with an area not exceeding twenty-five hundred square feet, may have an unlimited length of show window under the following conditions: (a) The maximum depth of show window shall be three feet.
(4)OCCUPANCY. Street floor lobbies serving as exit passageways may be occupied by newsstands, candy and tobacco stands, information booths or similar occupancies, if such stands or booths are constructed of noncombustible materials, or of materials which comply with the requirements of section 27-348 of article five of subchapter five of this chapter for interior finish for exit passageways, provided that such stands or booths: a. do not occupy more than one hundred square feet or five percent of the net floor area of the lobby, whichever is greater; and b. do not reduce the required clear width of the lobby at any point; and c. if constructed of combustible materials are protected by no less than two automatic sprinkler heads. Water for such sprinkler heads may be supplied from the domestic water supply system.
