A 15 11 35 35 34 42 43 43 41 43 50 52 53 43 46 50 31 B 21 24 40 31 36 42 45 46 43 50 51 54 55 50 41 51

to span more than a 6 mm (1/4") gap. Larger openings should be filled with drywall mud or gypboard.

Resilient Channel

Resilient channel is a flexible strip of metal designed to support layers of gypboard, while providing a measure of mechanical isolation against structure borne vibrations. A group of wall constructions is shown in Fig. 10.7. Note that the channel is attached to the studs only on one side. Resilient channel should be installed with the open side up so that the weight of the gypboard tends to open the gap between the stud and the board. A filler strip is used at the base plate as a solid protection against impact. The gypboard is attached with drywall screws to the channel and care must be exercised to avoid screwing through the channel and into the studs, which short-circuits the isolation. When there are bookcases or other heavy objects that must be wall mounted, resilient channel is not a good choice since these items must be bolted through into the structure.

There are a number of products called resilient channel on the market. Some are more effective than others. A type that is spoon-shaped and can be attached only on one side is preferable to the furring channel type, which is hat-shaped and may be attached on both sides. The latter is often improperly installed, rendering it ineffective.

Figure 10.5 Transmission Loss of Single Metal Stud Walls (California Office of Noise Control, 1981)

Single Metal Stud Wall -3 5/S" Stud 1 Layer 5/&" Drywall Each Side A - Without Insulation B - R-

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