Except as provided in paragraphs (b) and (c) of this section, all interior stairways shall be enclosed with walls and partitions providing fire resistance as follows:
In buildings exceeding three stories in height – Two hours (Except open plan schools equipped throughout with an approved automatic sprinkler system as defined in Article II of Chapter15-16 of this Code);
In buildings not exceeding three stories in height – One hour (Except open plan schools equipped throughout with an approved automatic sprinkler system as defined in Article II of Chapter15-16 of this Code);
In institutional buildings – Two hours;
In open plan schools equipped throughout with an approved automatic sprinkler system as defined in Article II of Chapter15-16 of this Code – Noncombustible.
(The enclosure shall be constructed of noncombustible materials having fire-resistant properties not less than that of one-fourth-inch thick wired glass installed in steel sash and frames. Doors provided therein shall be not less fire-resistant than the enclosure, shall close the opening completely with only such clearance as is necessary for proper operation, and shall be equipped with approved self-closing devices. Whenever such doors must be maintained open, approved electromagnetic hold-open devices shall be provided, arranged to close the doors automatically when activated by the building’s fire alarm system or by specially installed approved smoke detectors located above such door openings.)
Stairway enclosures shall not be required in buildings of Types I-A, I-B and I-C construction for the following stairs:
Stairs from the second floor to the main exit floor and serving the second floor only, except in hazardous use units, in multiple dwellings and in institutional units where habitable rooms are located on the second floor;
Stairs in mercantile and business units from a basement sales space to the main exit floor level, constituting not more than 50 percent of the total required width of exit stairs.
Stairway enclosures shall not be required in buildings of any type of construction for the following stairs:
In residential units, stairs serving one dwelling unit only and entirely contained within such dwelling unit;
In assembly units, stairs connecting any balcony level with the main floor level;
In all occupancies, stairs connecting a mezzanine floor to the floor immediately below.
Group homes located in one-family dwellings shall require vertical cutoffs for one of the required interior stairs either at the first floor or second floor levels and on any floor above the second floor.
The stair enclosure shall be of one-hour fire- resistive construction and the door opening shall be protected with a self-closing one and three-fourths-inch solid-core wood door installed in a one and three- fourths-inch solid rabbeted frame or No. 16 gauge metal frame. The other required stair shall be enclosed as required by Sections15-8-140 and 15-8-180, and provide protection to the exterior of the building.
Interior stairways in intermediate care facilities for the developmentally disabled – 15 or less shall have a vertical cutoff with a one and three-fourths- inch solid-core door equipped with a self-closing device located at either the top or the bottom of the stairway. The frame of such door shall be one and three-fourths inch solid rabbeted frame or No. 16 gauge metal frame. Stair enclosures in such facilities shall be of one-hour fire-resistive construction. Other required stairways in such facilities shall be enclosed as required by Sections15-8-140 and 15-8-180 of this Code and shall provide protection for the exterior of the building.
(Prior code § 62-3.2; Amend Coun. J. 12-21-84, p. 12140; Amend Coun. J. 6-27-90, p. 17607)