Interpretation #: CEB-2022-20-2014 IBC-508.3

Building or Fire Safety Law Interpreted

675 IAC 13-2.6 2014 Indiana Building Code, Section 508.3 Nonseparated occupancies. Buildings or portions of buildings that comply with the provisions of this section shall be considered nonseparated occupancies.

Issue

What is the intended meaning of the word "nonseparated" in Section 508.3 of the 2014 Indiana Building Code (IBC)?

Interpretation of the State Building Commissioner

In the context of Section 508.3 of the 2014 IBC, nonseparated means the absence of fire-resistance-rated assemblies between areas of differing occupancy groups. It is the opposite of separated, which throughout the code generally means division by fire-resistance-rated construction for the purposes of creating protected buildings, fire areas, shafts, exits, and other areas, and, in this section specifically, protecting different occupancy groups from the hazards associated with their neighbors within the structure. Separated does not mean division between spaces by nonrated physical barriers, and therefore nonseparated does not mean the absence of such barriers.

Rationale

In this dispute, a structure contains multiple occupancy groups. The designer states that he has employed a strategy of nonseparated mixed occupancies in accordance with Section 508.3 to meet allowable area requirements. The local official states that because adjacent tenants of different occupancies are closed off from one another by a nonrated partition without openings, the structure cannot be considered nonseparated, but must be designed in accordance with the Section 508.4 requirements for separated mixed occupancies. They are saying that to qualify as nonseparated, occupants must be able to move from the space of one occupancy group directly to the space of the other. This is incorrect.

Neither separated nor nonseparated are formally defined in the 2014 IBC, but their meaning can be inferred from context. In general terms, when the code uses the word separated, it is typically in reference to using fire-resistance-rated construction to create barriers between or around specific areas of a structure for the purpose of protecting those areas from the transfer of fire and its byproducts. Nonseparated simply means the absence of fire-resistance ratings on these barrier assemblies. It does not necessarily mean an absence of the assemblies themselves (though in a successful nonseparated mixed use design, partitions may or may not exist between the occupancies, depending on how the designer wishes the structure to function).

Regarding the text of Section 508.3 specifically, the term is used to describe one of several acceptable allowable-area design strategies for including two or more different occupancy groups within a single structure. The section is part of the parent Section 508 "MIXED USE AND OCCUPANCY", which also includes child sections on the other allowable strategies, namely 508.2 "Accessory occupancies", and 508.4 "Separated occupancies" (Section 508.1 also makes clear that a combination of any of these three strategies is acceptable as well).

All three of these strategies are based on the question of whether any assembly that divides the various occupancy groups must be fire-resistance-rated or not. That is the context in which the terms separated and nonseparated are used here. Table 508.4 shows under what circumstances separations are normally required between occupancies, and in each case what degree of fire-resistance the separation must provide. Note that there are no entries in the table for separations without associated fire-resistance ratings, which makes the very notion of a nonrated separation meaningless. If in the context of this section separation requires an associated fire-resistance rating, then it follows that a nonrated barrier cannot be considered a separation, and therefore, contrary to the local official's assertion, a nonseparated condition does not require the absence of a nonrated barrier.

This all demonstrates that when the code addresses separated occupancies and nonseparated occupancies in the context of allowable-area design strategies, the presence or absence of nonrated physical barriers between spaces is irrelevant. They represent nothing more than the demising walls between tenants or between other areas of a structure, and their design, construction, location, or even the question of whether they exist at all, are largely concerns of design, function, property, and privacy, all of which are matters that lie outside the scope of the fire protection and public safety issues addressed by Section 508.