Finger Lakes Building Officials, Inc.

An Affiliated Member of the New York State Building Officials Conference

June 2, 2003

RE: Return air from a corridor
9 NYCRR 1004.2(a)(4)
BC 1004.3.2.4, 1005.3.4.1

I am writing in response to your letter asking whether the previous provisions of the Uniform Fire Prevention and Building Code (here Title 9B) permitted the ceiling space within a corridor, in a building of occupancy classification C5.2, to be used as a ventilation plenum where fire dampers are provided at the fire-rated separations of the corridor. It is our opinion that such a use was not permitted.

You have proposed constructing a building using one hour fire-rated corridors having a non-rated drop ceiling. You have asked whether the space above the drop ceiling may be used as a ventilation plenum if fire dampers are provided at the fire-rated separations of the corridor. Section 1004.2(a)(4) of Title 9B stated, in part, "stairways, exits, hoistways, attics and shafts other than those used exclusively for ventilating purposes, shall not be used as a plenum chamber." Although this section provided exceptions for specific situations, none of the exceptions applied to the situation you describe.

You have also asked whether this situation is permitted in the Building Code of New York State (BCNYS). The BCNYS section 1004.3.2.4 prohibits the use of such an above ceiling space as a plenum. Where the ‘corridor' (as defined in NYCRR Title 9B) is an ‘exit passageway' (as defined in the BCNYS), section 1005.3.4.1 prohibits not only the use of the space as a plenum, it also prohibits the installation of ductwork through this space. Section 1005.3.4.1 prohibits the penetration of an exit enclosure assembly except as required and permitted in that section.

This advisory opinion is rendered based upon the information provided. Administration and enforcement of the code are within the jurisdiction of the local authority. If you have questions regarding this advisory, please call me at (518) 474-4073.

Sincerely,
James L. Harding, P.E.
Senior Building Construction Engineer
Codes Division
Al03-094

Finger Lakes Building Officials Association, Inc.
3100 Atlantic Ave.
Penfield, NY 14526
info@flboa.com