Interpretation #: CEB-2022-32-2014 IBC-202

Building or Fire Safety Law Interpreted

675 IAC 13-2.6, 2014 Indiana Building Code

Section 202 DEFINITIONS

FIRE AREA. FIRE AREA means the aggregate floor area enclosed by fire walls, fire barriers, exterior walls, or fire-resistance-rated horizontal assemblies of a building.

Issue

Whether, under the 2014 Indiana Building Code (IBC), the calculation of fire area includes the thickness of the fire area's boundary construction.

Interpretation of the State Building Commissioner

No, under the 2014 IBC, the calculation of fire area does not include the thickness of the fire area's boundary construction.

Rationale

The definition states that a "fire area" consists of a floor area that is enclosed by certain named boundaries. The exclusion from the fire area of the thickness of the boundary itself is implicit in the phrase "floor areas enclosed by [the named boundaries]" (emphasis added). That phrase puts the limit of the fire area at the interior surface of the area's boundary construction. If the boundary construction were intended to be included in the floor area, the definition would require different wording, or the addition of a specific statement that the boundary construction itself was to be included in the calculation. The definition provides no such statements however, but simply terminates the fire area at the interior surface of its boundaries.

It is also important to note that in the case of exterior walls, the interior-surface boundary limit is not conditioned in any way upon the presence of a fire-resistance rating for the wall, or upon the use of any fire-resistant materials in its construction. The definition names exterior walls as an acceptable boundary assembly without any reference to materials or ratings, and nothing in the definition treats such walls any differently from the other named boundary assemblies.