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FIRE PREVENTION AND BUILDING SAFETY COMMISSION
Department of Homeland Security

Written Interpretation of the State Building Commissioner

Interpretation #: CEB-2022-09-2010 IECC-5.4.3.4


Building or Fire Safety Law Interpreted
675 IAC 19-4 2010 Indiana Energy Conservation Code, Section 5.4.3.4 Vestibules. Building entrances that separate 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. Interior and exterior doors shall have a minimum distance between them of not less than 7 ft when in the closed position. The exterior envelope of conditioned vestibules shall comply with the requirements for a conditioned space. The interior and exterior envelope of unconditioned vestibules shall comply with the requirements for a semiheated space.

Exceptions:
a. Building entrances with revolving doors.
b. Doors not intended to be used as a building entrance.
c. Doors opening directly from a dwelling unit.
d. Building entrances in buildings located in climate zone 1 or 2.
e. Building entrances in buildings located in climate zone 3 or 4 that are less than four stories above grade and less than 10,000 ft2 in area.
f. Building entrances in buildings located in climate zone 5, 6, 7, or 8 that are less than 1000 ft2 in area.
g. Doors that open directly from a space that is less than 3000 ft2 in area and is separate from the building entrance.

Issue
Does Section 5.4.3.4 of the 2010 Indiana Energy Conservation Code (IECC) allow the use of an air curtain in lieu of a vestibule?

Interpretation of the State Building Commissioner
No. Section 5.4.3.4 of the 2010 IECC does not allow the use of an air curtain in lieu of a vestibule.

Rationale
The language of the code is clear. The section is not a performance code, but rather it specifically requires the use of vestibules in certain entry conditions. The code enumerates several exceptions to the regulation, but none of them name air curtains as allowable substitutions.

Posted: 03/30/2022 by Legislative Services Agency

DIN: 20220330-IR-675220107NRA
Composed: Dec 05,2022 2:49:24AM EST
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