April 2014: Channel Surfing

There is one product that has been around for over 50 years that has the potential to make or break your sound isolation goals.  Many owners, architects, and contractors like it. It’s what they know. It is cost-effective and doesn’t increase the overall thickness of partitions by more than ½”. When installed properly, it can be very effective; however, incorrect installation is very common.  Read on for what you should know about the infamous resilient channel.

For many building projects, partitions need to provide a high degree of sound isolation. The sound isolation criteria may be code-driven as in the case of multifamily residential projects, or they may be driven by a need for isolation from a loud/active adjacency or for speech privacy. In wood-framed buildings or partitions with 20 gauge metal studs or thicker, sound easily transmits from one side of the partition to the other due to the stiffness of the framing members and the rigid connections of the components in the assembly. Resilient channels, sometimes called Z-channels because of their Z-shaped profile when viewed in section, have the potential to improve the sound isolation of common partition types by providing a resilient connection in the assembly.

image of resilient channel

ClarkDietrich RC Deluxe

The single leg or flange of resilient channels is attached to one side of studs or joists and supports up to two layers of drywall. The drywall is not directly in contact with the studs or joists. It is this decoupling of the drywall from structure that provides the boost in sound isolation.

Unfortunately, resilient channels can be a blessing and a curse.  It can be a practical means of meeting code-required sound isolation ratings in design. However, care must be taken to ensure that it is installed correctly or the actual sound isolation performance of the built partition can drop dramatically. Resilient channels must be installed perpendicular to the framing members with the center of the holes directly over the studs or joists. In walls, the single leg of resilient channels attached to the studs should be installed facing down, which allows the drywall to swing away from the studs. Drywall fasteners must not come in contact with the structural framing members.

Installation photo of resilient channel

RC Deluxe installed correctly. 

Numerous products are marketed as resilient channels; however, truly “resilient” channels only have one mounting flange, are constructed of 25 gauge sheet metal or thinner, and have elongated holes/slots to allow for ample deflection. Double legged channel does not deflect very much and results in less improvement in sound isolation relative to single legged channel.

Image of Double Legged Channel

Double legged channel 

Heavy duty/thicker gauge resilient channels must be loaded appropriately for the drywall to remain resilient. Use these products with caution.

There are other options for achieving a higher degree of sound isolation without the use of resilient channels:  Stud isolation clips, sound-engineered gypsum board, viscoelastic damping compounds, and double stud walls to name a few. As the saying goes, “There is a time and a place for everything.” Resilient channels have its place as one, practical option for achieving sound isolation design goals.

All photos:  Courtesy of ClarkDietrich.

May 2014: Stream On!
March 2014: It’s Electric