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A smokeproof tower shall consist of an enclosed stairway accessible only from a vestibule or balcony having openings to the outside or to an interior smoke shaft as hereinafter provided. Smokeproof towers shall conform to all applicable requirements for interior stairs and with the provisions of Sections 13-160-370 to 13-160-420, inclusive.
(Prior code § 67-11)
(a) Stairways shall be constructed entirely of non- combustible materials and shall be enclosed by walls providing fire resistance of not less than three hours. If two smokeproof towers are provided the stairways shall be constructed entirely of noncombustible materials and shall be enclosed by walls providing fire resistance of not less than two hours.
(b) There shall be no openings in walls separating the enclosure from the interior of the building. Openings in an exterior wall of the enclosure shall be permitted only when such openings are located not less than 30 feet from any opening in the walls of the same building or an adjacent building. Such openings in an exterior wall shall be protected by fixed or automatic fire windows or shutters.
(c) The bottom of an enclosure and the top of an enclosure shall be of construction providing fire resistance of not less than three hours. If two smokeproof towers are provided the bottom of an enclosure and the top of an enclosure shall be of construction providing fire resistance of not less than two hours.
(Prior code § 67-11.1)
Access to the stairway at each story shall be through a vestibule or balcony complying with the following requirements:
(a) Except when an interior smoke shaft is provided, the vestibule or balcony shall be located on an exterior wall not subject to a severe fire exposure hazard.
(b) Every vestibule or balcony shall have an opening to a public way, yard or court or to an interior smoke shaft complying with the requirements of Section 13-160-420.
(c) Such openings shall have an area not less than one-half the area of the exit doors leading from the buildings to the vestibule or balcony and shall be located not less than four feet above the floor and not more than six inches below the ceiling of the vestibule or balcony. Unless such opening faces a public way, yard or court not less than 40 feet wide, the opening shall be protected with a fire shield complying with the requirements of Section 13-160-390. In any case, the yard or court shall have a minimum width of 20 feet and a minimum area of 400 square feet.
(d) The floors, walls and ceilings of all vestibules or balconies shall be of construction providing fire protection of not less than three hours.
(e) When openings are protected by fire shields, the level of the vestibule or balcony floor shall be at the level of the floor of the building which it serves or shall be accessible therefrom by ramps having a grade of not more than one in 10. When openings are not protected by fire shields, the vestibule or balcony floor shall be so placed as to prevent the possibility of blocking the doors by snow or ice but shall be not more than seven and one-half inches below the level of any story. In no case shall there be any step from the vestibule or the balcony to the stair enclosure.
(Prior code § 67-11.2; Amend Coun. J. 6-14-95, p. 2841)
When fire shields are provided to protect exterior openings of balconies or vestibules, such fire shields shall comply with the requirements of this section.
(a) Fire shields shall comply with all applicable requirements for fire windows as provided in Section 15-12-160.
(b) Fire shields shall have an opening sash having a clear area not less than as required in Section 13-160-380(c), arranged to open automatically in case of fire to the full limit and to be held securely in such open position. Provision shall be made for the manual opening or closing of the sash.
(c) The automatic opening of the sash shall be actuated by approved devices located inside the building within five feet of the door from the building to the vestibule or balcony and located also on the ceiling of the vestibule or balcony. Such devices shall be designed to operate as a result of rate of temperature rise or when the surrounding air reaches a temperature of 120 degrees Fahrenheit.
(Prior code § 67-11.3)
(a) The openings from the building to the vestibule or balcony and from the vestibule or balcony to the stair way enclosure shall be protected with self- closing Class B fire doors.
(b) All windows of the building or structure facing on a yard or court within 30 feet of the vestibule or balcony shall be protected with Class E fire doors, fire windows, fire shutters or other approved opening protectives complying with the requirements of Section 15-8-110.
(Prior code § 67-11.4)
The smokeproof tower shall terminate at grade level and shall have access directly to a public way, to an open area leading to a public way, or to an exit corridor leading to a public way which is enclosed with construction providing fire resistance as required for the stairway enclosure.
(Prior code § 67-11.5)
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