Research conducted by ROCKFON and NGC Testing Services1 shows that a lightweight plenum barrier positioned vertically above the wall, blocking the plenum, can provide a STC/CAC 40 level of blocking when combined with a stone wool ceiling system. This option can decrease the cost of the ceiling, allow for greater aesthetic flexibility and prevent the need to control noise leaks through the ceiling system. The plenum barrier can be installed quickly and easily, and does not need to extend around the entire perimeters of both rooms2.
- 5/8" gypsum board (type X) – 1 layer
- Quick install3 (no tape or caulk)
- Alternative STC 40 plenum barrier options
- 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
- CAC 41 (with plenum barrier)
- Lab test #NGC0615037
- 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 test4 #TL-93-343)
1 Madaras, G. and Heuer, A. (2016). “Optimizing Ceiling Systems and Lightweight Plenum Barriers to Achieve Ceiling Attenuation Class (CAC) Ratings of 40, 45 and 50”. Proceedings of the New England NoiseCon-16: Revolution in Noise Control conference, Providence, RI, 13-14 June, 2016. Electronic publication by the Institute for Noise Control Engineering.
2 Kruger, K. "The Effect of Various Parameters on the Sound Isolation between Offices with Suspended Ceilings." Canadian Acoustics, 16 (2), 1988, pp. 9-23.
3 The 'quick install' method for the gypsum board plenum barriers uses rectangular cut pieces of gypsum board without cutouts for penetrating elements. Large holes in the plenum barrier around penetrating elements are stuffed with stone wool, batt, and insulation. Small holes, joints, screw heads, perimeter edges, etc. are NOT taped or caulked/sealed.
4 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.