Building entrances shall be protected with an enclosed vestibule, with all doors opening into and out of the vestibule equipped with self-closing devices. Vestibules shall be designed so that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time. The installation of one or more revolving doors in the building entrance shall not eliminate the requirement that a vestibule be provided on any doors adjacent to revolving doors.
Exceptions: Vestibules are not required for the following:
- Buildings in Climate Zones 1 and 2.
- Doors not intended to be used by the public, such as doors to mechanical or electrical equipment rooms, or intended solely for employee use.
- Doors opening directly from a sleeping unit or dwelling unit.
- Doors that open directly from a space less than 3,000 square feet (298 m2) in area.
- Revolving doors.
- Doors used primarily to facilitate vehicular movement or material handling and adjacent personnel doors.
- Doors that have an air curtain with a velocity of not less than 6.56 feet per second (2 m/s) at the floor that have been tested in accordance with ANSI/AMCA 220 and installed in accordance with the manufacturer’s instructions. Manual or automatic controls shall be provided that will operate the air curtain with the opening and closing of the door. Air curtains and their controls shall comply with Section C408.2.3.