A sound blocking level of STC 40 can provide privacy between rooms if the speech level is no louder than general conversation. Once speech levels rise, phrases and sentences can be understood in adjacent rooms and will likely disrupt people. Acoustic standards, guidelines and building rating systems occasionally permit a STC rating as low as 40. However, most require blocking levels of STC 45 or higher1. A STC 40 level of blocking should be considered a minimum as privacy cannot be achieved at levels below STC 40.
- Chicago Metallic Tee-Bar suspension grid
- ROCKFON stone wool ceiling panels – optimized for sound absorption
- Noise control measures for noise flanking paths through lights, grilles, diffusers – not required
- 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)
- Alternative STC 40 wall options
1 For an overview of the sound blocking levels required by the various acoustics standards, guidelines and building rating systems refer to Madaras, G. "A Guide on the Four Categories for Acoustics Criteria in Building Standards and Guidelines." Acoustical Interior Construction, Jul-Sep 2016, pp. 27.
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.