717.6.3 Non- fire-resistance-rated floor assemblies.

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.

717.7 Flexible ducts and air connectors.

Flexible ducts and air connectors shall not pass through any fire-resistance-rated assembly. Flexible air connectors shall not pass through any wall, floor or ceiling.

Section BC 718: Concealed Spaces

718.1 General.

Fireblocking and draftstopping shall be installed in combustible and noncombustible concealed locations in accordance with this section. Fireblocking shall comply with Section 718.2. Draftstopping in floor/ceiling spaces and attic spaces shall comply with Sections 718.3 and 718.4, respectively. The permitted use of combustible materials in concealed spaces of buildings of Type I or II construction shall be limited to the applications indicated in Section 718.5. Installations of fireblocking and draftstopping shall comply with the special inspection requirements of Chapter 17.

   Exception: Concealed spaces that are sprinklered in accordance with Chapter 9 or are constructed as a shaft.

718.2 Fireblocking.

In combustible and noncombustible construction, fireblocking shall be installed to cut off concealed draft openings (both vertical and horizontal) and shall form an effective barrier between floors, between a top story and a roof or attic space. Fireblocking shall be installed in the locations specified in Sections 718.2.2 through 718.2.7.