717.6.3 Non- fire-resistance-rated floor assemblies.
BC § 717.6.3
Duct systems constructed of approved materials in accordance with the New York City Mechanical Code that penetrate non- fire-resistance-rated floor assemblies shall be protected by any of the following methods: 1. A shaft enclosure in accordance with Section 713.
2.The duct connects not more than two stories and the annular space around the penetrating duct is protected with a listed noncombustible material that resists the free passage of flame and the products of combustion.
3.In floor assemblies composed of noncombustible materials, a shaft shall not be required where the duct connects not more than three stories, the annular space around the penetrating duct is protected with an approved noncombustible material that resists the free passage of flame and the products of combustion and a fire damper is installed at each floor line. Exception: Fire dampers are not required in ducts within individual residential dwelling units.
