607.6.1 Through penetrations.
MC § 607.6.1
In occupancies other than Groups I-2 and I-3, a duct and air transfer opening system constructed of approved materials in accordance with this code that penetrates a fire-resistance-rated floor/ceiling assembly that connects not more than two stories is permitted without shaft enclosure protection provided that a listed fire damper is installed at the floor line and the penetration is firestopped or the duct is protected in accordance with Section 714.4 of the New York City Building Code. For air transfer openings, see Item 6, Section 712.1.9 of the New York City Building Code. Exception: A duct serving a dwelling unit is permitted to penetrate three floors or less without a fire damper at each floor provided such duct meets all of the following requirements.
1.The duct is contained and located within the cavity of a wall and is constructed of steel having a minimum thickness of 0.0187 inch (0.4712 mm) (No. 26 gage).
2.The duct opens into only one dwelling or sleeping unit and the duct system is continuous from the unit to the exterior of the building.
3.The duct does not exceed a 5 inch (127 mm) nominal diameter and the total area of such ducts does not exceed 100 square inches (64 516 mm 2 ) for any 100 square feet (9.3 m 2 ) of the floor area.
4.The annular space around the duct is protected with materials that prevent the passage of flame and hot gases sufficient to ignite cotton waste where subjected to ASTM E 119 or UL 263 time-temperature conditions under a minimum positive pressure differential of 0.01 inch (2.49 Pa) of water at the location of the penetration for the time period equivalent to the fire-resistance rating of the construction penetrated.
5.Grille openings located in a ceiling of a fire-resistance-rated floor/ceiling or roof/ceiling assembly are protected with a listed ceiling radiation damper installed in accordance with Section 607.6.2.1.
