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Article #1470 - Vestibule Requirements in Commercial Buildings - Code Notes

[2003 IECC, 2006 IECC, 2003 IBC, 2006 IBC]

Floor area of a lobby and corridor.
Floor area of a lobby and corridor.

Commercial building designers are required to install vestibules on the primary entrance doors leading from spaces greater than or equal to 3000 square feet in all buildings. Designers are unclear on what is included in determining the 3000 ft² floor area that defines a space. For example, it is unclear if an entrance door leading from a lobby that is attached to a corridor which has a total area of 3000 ft² must meet the vestibule requirement.

There is also confusion as to which doors must have vestibules when several doors leave a space greater than or equal to 3000 ft².

The 2003 and 2006 IECC requires that the primary entrance doors leaving from spaces 3000 ft² or greater have vestibules. The vestibules reduce the infiltration load on the space by creating an air lock. This requirement typically applies to large "box" stores where the building entrance is directly into the resale area or other occupancies with large lobbies, e.g. a hotel. There are no minimum dimensions for the vestibule under the provisions of the 2003 and 2006 IECC but the codes require that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time.

Interior and exterior vestibule doors.
Interior and exterior vestibule doors.

Plan Review:

  1. Verify that doors separating conditioned space from the exterior that do not have vestibules are exempt from the requirement.
  2. Verify that doors separating conditioned space from the exterior leading to spaces 3000 ft² or greater contain a vestibule.
  3. Verify that the doors leaving into and out of the vestibule are designed so that in passing through the vestibule it is not necessary for the interior and exterior doors to open at the same time. Also verify that the doors meet the requirement for means of egress doors as stated in 2003 and 2006 IBC Section 1008.
  4. Verify that the building assemblies between the conditioned space and the vestibule meet the envelope requirements of Section 802 of the 2003 IECC and Section 502 of the 2006 IECC.

Inspection:

  1. Verify that the vestibule has been constructed per the approved building plans and specifications.
  2. Verify that the doors leading into and out of the vestibule include self closing devices.

Code Citations*

IECC 2003 Section 802.3.6 and IECC 2006 Section 502.4.6 Vestibules

A door that separates conditioned space from the exterior 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.

Exceptions:

  1. Buildings in Climate Zones 1a through 4b as indicated in Table 302.1 (See Energy Code Climate Zones ) [2003 IECC]; Buildings in Climate Zones 1 and 2 as indicated in Table 301.1 [2006 IECC].
  2. Doors not intended to be used as a building entrance door, such as doors to mechanical or electrical equipment rooms.
  3. Doors opening directly from a guestroom or dwelling unit [2003 IECC]; Doors opening directly from a sleeping unit or dwelling unit [2006 IECC].
  4. Doors that open directly from a space less than 3,000 square feet (298 m²) in area.
  5. Revolving doors.
  6. Doors used primarily to facilitate vehicular movement or material handling and adjacent personnel doors.

2003 and 2006 IBC Section 1203.4.1.1 Adjoining spaces.

Where rooms and spaces without openings to the outdoors are ventilated through an adjoining room, the opening to the adjoining rooms shall be unobstructed and shall have an area not less than 8 percent of the floor area of the interior room or space, but not less than 25 square feet (2.3 m²). The minimum openable area to the outdoors shall be based on the total floor area being ventilated.

2003 IBC Section 1023.1 and 2006 IBC Section 1024.1 General Exception 2.

A maximum of 50 percent of the number and capacity of the exit enclosures is permitted through a vestibule provided all of the following are met:

  1. The entire area of the vestibule is separated from the areas below by construction conforming to the fire-resistance rating for the exit enclosure.
  2. The depth from the exterior of the building is not greater than 10 feet (3048 mm) and the length is not greater than 30 feet (9144 mm).
  3. The area is separated from the remainder of the level of exit discharge by construction providing protection at least the equivalent of approved wired glass in steel frames.
  4. The area is used only for means of egress and exits directly to the outside.

*Copyright, 2003, International Code Council(Link opens in a new window) , Inc. Falls Church, Virginia. Reproduced with permission. All rights reserved. 2003 International Energy Conservation Code

*Copyright, 2006, International Code Council(Link opens in a new window) , Inc. Falls Church, Virginia. All rights reserved. 2006 International Energy Conservation Code .

*Copyright, 2003, International Code Council(Link opens in a new window) , Inc. Falls Church, Virginia. Reproduced with permission. All rights reserved. 2003 International Building Code

*Copyright, 2006, International Code Council(Link opens in a new window) , Inc. Falls Church, Virginia. All rights reserved. 2006 International Building Code .

PNNL-SA-48710
Last Modified: 2009-05-13