Resilient Channels and their failure to perform within the construction market.
It is a question why we still use resilient channels within construction today considering the long list of risk factors that pertains to the name.
Resilient channel was brought into building assemblies in the 1960’s as a less expensive way to mechanically isolate the drywall from the studs. Though it is seen by many as the cheapest way to quickly sound proof an assembly, unfortunately due to an endless list of risk factors and problems it isn’t. Ted White from The Soundproofing Company states “Much better to use resilient sound clips and Drywall Furring Channel. For a low cost solution you can install a ceiling with these steel clips + channel that would put any resilient channel ceiling to shame.” (http://www.soundproofingcompany.com/soundproofing-articles/is-resilient-channel-appropriate-for-sound-isolation/)
Below is a list of the most common risk factors that one should consider before starting a project:
Resilient Channel is frequently drawn on the plans upside down and/or installed upside down in a wall assembly. When installing resilient channel it is important that the leg or mounting flange be installed down which helps to pull the channel away from the wall. When the mounting flange of the resilient channel is installed on the top, the total weight of the drywall ends up pushing the channel into the framing members thus creating a short circuit in the wall assembly, which results in a lower STC rating.
The building assembly is overloaded with drywall. If an extra layer or more of drywall is added by the subcontractor that is above the specified assembly, the final structure weight on the resilient channel can cause the wall to touch the floor, causing a short circuit in the assembly build, subsequently creating a poorly sound insulated assembly. Due to its weakness in strength and higher level of flexibility the single leg resilient channel compared to
The first single leg resilient channel that gives us most lab test results actually no longer exists. In 1985 USG stopped manufacturing the resilient channel that makes up most of the lab test results today that we see. Most of these results are based on sound tests conducted over 10 years ago on diverseassemblies. Because there isn’t a benchmark for manufacturing resilient channel and it is a product that is not specified by the SSMA, the vast range resilient channels in the market differ significantly in their resilient (rigidity) attributes. Resilient channel that is excessively rigid, or have holes with the incorrect dimensions or profiles, have the consequences of decreased STC ratings.
A fastener is placed inaccurately or the wrong sized fastener is used. If a fastener unintentionally makes contact with a framing member at the time of the installation of the drywall to the resilient channel, it will create a short circuited assembly and will essentially create a poorly sound insulated assembly. Typically when attaching drywall to the resilient channels the assembly is designed to use 1-inch screws, but often installers use longer drywall screws because of ease of installation and to save time. This is the undoing, and essentially what short circuits the resilient channel assembly. The longer screws usually are long enough to pass through the drywall, through the resilient channel and into the framing member. This is why the width between the drywall and the stud has to be correct with a decoupling product. It can’t be too thick or you will lose square footage, and it can’t be too thin or else you may short circuit the assembly, like the furring channel mentioned above. Resilmount sound isolation clips with 7/8” tall furring channel are the perfect option for sound proofing your walls or ceilings. The sound isolation clips are thick enough to provide the safe guard of short circuiting and screwing through the drywall to the stud, but thin enough to save square footage within the room.
The resilient channels are installed too close to each other. If this does occur, the combined rigidity of the assembly will be too stiff and not flexible enough to provide the sought after STC rating.
Destroyed during and on arrival to site. Resilient channels are somewhat fragile, flimsy and exposed to freight abuse or onsite storage. A small twist or bow in the resilient channel can quickly become the source of assembly short circuiting.
Owner or resident actions post-construction. Throughout the lifetime of a building structure, if the landlord, resident or owner mounts anything to the wall assembly, it can end up being short circuited very quickly. This is due to the items being attached to the framing members by fasteners, which unfailingly causes a short circuiting.
Force of furniture or other appliances against a wall. If somebody moves heavy furnishings or heavy appliances against the wall with pressure on the wall, it can make the resilient channel bow somewhat and bring it into contact the studs, therefore creating a short circuit in the assembly, decreasing its STC value. Resilient sound isolation clips have a more structure to them than the resilient channels themselves so when there is pressure on the wall the sound isolation clips wont bow or twist but keep their positions within the assembly.
In conclusion resilient channel has an astounding post construction failure rate of 90% due to all of these risk factors. When sound proofing an assembly it is imperative to avoid mistakes and short circuiting, because as we all know once that assembly is sealed in with gypsum board there is no real going back. That is why Resilmount sound isolation clips are the more ‘fool-proof’ option when sound proofing an assembly. Also with its red rubber absorbing properties Resilmount sound isolation clips will usually provide a higher STC rating than that of resilient channel, when based on the same assembly components.