N.Y.C. Admin. Code § BC 808: Section BC 808: Acoustical Ceiling Systems

808.1 Acoustical ceiling systems.

The quality, design, fabrication and erection of metal suspension systems for acoustical tile and lay-in panel ceilings in buildings or structures shall conform to generally accepted engineering practice, the provisions of this chapter and other applicable requirements of this code.

808.1.1 Materials and installation.

Acoustical materials complying with the interior finish requirements of Section 803 shall be installed in accordance with the manufacturer's recommendations and applicable provisions for applying interior finish.

808.1.1.1 Suspended acoustical ceilings.

Acoustical ceilings that are to be suspended below floor or roof construction by means of a framing system shall consist of supporting hangers of minimum 1/4-inch diameter (6.4 mm) steel rods, carrying channels of minimum 1 1/2-inch deep (38.1 mm) cold-rolled steel weighing 0.440 pounds per linear foot (0.681 kg/m), and a supporting grid complying with Appendix R. Use of wire hangers shall not be permitted. Direct hung suspension systems shall not be permitted.

Exception: Acoustical ceiling systems in Groups R-2 and R-3 occupancies shall be permitted to be installed in accordance with ASTM C 635 and ASTM C 636 without modifications.

808.1.1.2 Fire-resistance-rated construction.

Acoustical ceiling systems that are part of fire-resistance-rated construction shall be installed in the same manner used in the assembly tested and shall comply with the provisions of Chapter 7.