Resilient channels have long been a viable and cost-effective solution for minimizing sound transmission through wall assemblies to adjoining rooms. Combined with standard batt insulation and gypsum board, these channels can create wall assemblies with optimal sound attenuation at a lower cost than assemblies built with today’s alternative and expensive acoustical building products.
But in order for them to reach their maximum acoustical-performance potential, resilient channels must be installed properly. To uncover best practices for installing resilient channels, we will look at how they function, examine common installation errors, and discuss how to avoid these errors and achieve optimal acoustical control.
How Resilient Channels Work
In wall assemblies, resilient channels act as a decoupler—a means for attaching gypsum board to the studs without allowing the two components to touch. This separation impedes the transmission of sound waves through the wall cavity by obstructing their path. The less contact that resilient channels make with the studs, and the less rigid they are, the better they can dampen sound waves.
Traditional resilient-channel designs feature a long, slotted hole with circular ends that are wider than the middle portion of the slot. Because of the unique shape, these holes are commonly referred to as “dog bones.” These slots are 3 inches long and 3/8-inch wide in the center, and are spaced 4 inches on center along the sloping side of the resilient channel.
Resilient channels can help contactors create wall assemblies with high sound-transmission class (STC) ratings. In order for them to perform as intended, however, it is critical that they, and other wall-assembly components, be installed correctly. Below are some of the most common errors that happen when installing resilient channels, as well as tips on how to avoid them.
Using the wrong screws
One of the most common installation errors is using screws that are too long and that make direct contact with the stud. This gives sound vibrations a direct path to the stud, which will then permit the stud to transmit the vibrations to the next room. This installation error, known as short circuiting, has the effect of nullifying the acoustical advantages of the resilient channel and significantly reducing the wall assembly’s STC rating.
To avoid short circuiting, installers should use screws whose lengths equal the gypsum board’s depth plus 3/8 of an inch. Also, never install the channels directly over a stud. Another way to prevent a short circuit is to include a steel resilient-channel clip. These clips slide onto the resilient channel and act as an impenetrable washer between the it and the stud. Screws will not penetrate the clip because it’s a heavier-gauge product. This additional layer adds extra protection from short circuiting. For a visual representation of the effects of short circuiting on the sound transmission loss of a wall assembly, see Figure 1 below.