§ 27-769 Acoustical isolation of dwelling units.
AC § 27-769
(a)Airborne noise.
(1)Walls, partitions, and floor-ceiling constructions separating dwelling units from each other or from public halls, corridors, or stairs shall have a minimum sound transmission class (STC) rating of forty-five for airborne noise. This requirement shall not apply to dwelling unit entrance doors. However, such doors shall fit closely and not be undercut. For permits issued after January first, nineteen hundred seventy-two, the STC required shall be fifty for airborne noise. For permits issued after April thirtieth, nineteen hundred seventy-three, dwelling unit entrance doors shall have a minimum STC of thirty-five.
(2)STC ratings shall be obtained by tests conducted in accordance with the procedures of reference standard RS 12-2 except as provided in paragraph three of this subdivision.
(3)The STC ratings of construction assemblies as listed in reference standard RS 12-2 may be used to determine conformance with the requirements of paragraph one of this subdivision and with any other section that requires a specific STC rating.
(4)Penetrations or openings in walls, partitions, or floors for pipe sleeves, medicine cabinets, hampers, electric devices, or similar items shall be packed, sealed, lined, back-plastered, or otherwise isolated by sufficient mass to maintain the required STC ratings.
(5)Where grilles, registers, or diffusers in one dwelling unit are connected by duct-work with grilles, registers, or diffusers in another dwelling unit, and where such connecting duct is less than seven feet long, it shall be lined with duct lining; otherwise, an approved sound attenuating device shall be installed therein. Duct lining shall conform to the requirements of subchapter thirteen of this chapter.
(b)Structure-borne noise.
