Due to the many drawbacks, attempting to achieve a STC 40 level of blocking with a modular, acoustic ceiling alone is not advised. First, you would need ceiling panels with a minimum CAC 40 rating and a high NRC rating (0.70 or higher). There are limited options for this level of performance. However, one option is ROCKFON Sonar dB (CAC 43, NRC 0.85). Second, is the problem controlling noise leaks through the ceiling due to lights, air devices and other elements. Testing conducted by ROCKFON and NGC Testing Services1 shows that these noise leaks can decrease the CAC of the ceiling system by 10 points.
- Chicago Metallic Tee-Bar suspension grid
- ROCKFON Sonar dB
- Noise control measures for noise flanking paths through lights, grilles, diffusers – required CAC 43
- Lab test #NGC6015038
- 1/2" gypsum board (type X) – 1 layer each side
- 3-5/8" steel studs (25 gauge) spaced 16" on center
- 1-1/2" thick ROXUL AFB® Semi-Rigid Batt Insulation
- STC 40 (lab test2 # TL-93-343)
1 Madaras, G. and Heuer, A. (2015) "Effects of Noise Flanking Paths on Ceiling Attenuation Class (CAC) Ratings of Ceiling Systems and Inter-Room Speech Privacy." Proceedings of Inter-Noise 2015, edited by Courtney Burroughs and George Maling, paper in15_083, San Francisco, CA, 9-12 August, 2015. Electronic publication.
2 The referenced laboratory test(s) are part of an extensive, multi-year, testing program conducted by the National Research Council Canada (NRCC) and published by the Institute for Research in Construction (IRC). For more details, including 1/3 octave band transmission loss data, refer to internal reports IRC-IR-693, October 1995 and IRC-IR-761, March 1998. The research program was partially funded by ROXUL, Inc. ROCKFON and ROXUL are subsidiaries of the ROCKWOOL Group.