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Code Question: Expert Staff Opinions

International Building Code
Chapter 5—General Building Heights and Areas

SECTION 508.2.2.1
IBC Interpretation No. 02-08
2006 Edition
Issued: 05-20-2008
BU_06_02_08

508.2.2.1 Construction. Where Table 508.2 requires a fire-resistance-rated separation, the incidental use area shall be separated from the remainder of the building by a fire barrier constructed in accordance with Section 706 or a horizontal assembly constructed in accordance with Section 711, or both. Where Table 508.2 permits an automatic fire-extinguishing system without a fire barrier, the incidental use area shall be separated from the remainder of the building by construction capable of resisting the passage of smoke. The partitions shall extend from the floor to the underside of the fire-resistance-rated floor/ceiling assembly or fire-resistance-rated roof/ceiling assembly above or to the underside of the floor or roof sheathing, or sub deck above. Doors shall be self- or automatic closing upon detection of smoke. Doors shall not have air transfer openings and shall not be undercut in excess of the clearance permitted in accordance with NFPA 80.

Q: In accordance with the provisions of Section 508.2.2.1 of the International Building Code, when an incidental use area is permitted by Table 508.2 to be protected with an automatic fire-extinguishing system fire barriers are not required to separate the incidental use area from the remainder of the building. Although fire barriers are not required, Section 508.2.2.1 contains prescriptive and performance requirements for the construction of the walls that separate the incidental use area from the remainder of the building.

Are smoke dampers “required” in construction that is capable of resisting the passage of smoke?

A: No. Smoke dampers are not “required” when the construction that separates an incidental use area from the remainder of the building complies with the prescriptive requirements as well as the performance requirements to resist the passage of smoke. The only openings addressed are those located in doors. There are no provisions to address openings located in the walls. Should openings be located in a wall, the performance requirements would require whatever construction methods are necessary to “prevent the passage of smoke” through the wall.

Where Table 508.2 permits protection by an automatic fire-extinguishing system without fire barriers, the partitions enclosing the incidental use area must simply be capable of resisting the passage of smoke. All of the detail requirements for the partitions to resist the passage of smoke are provided in Section 508.2.2.1. The wall construction described is not required to be either a smoke barrier conforming to the requirements of Section 709 or a smoke partition conforming to the requirements of Section 710.