Access to the stairway at each story shall be through a vestibule or balcony complying with the following requirements:
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.
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.
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.
The floors, walls and ceilings of all vestibules or balconies shall be of construction providing fire protection of not less than three hours.
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)