If you have ever worked on a “soundproof room” you are probably familiar with resilient furring channels, or what some people call z-bar. These mainstays for architectural acoustics have been used for decades and there are many successful installations.
Why Isolation Clips
The question we get asked from contractors is “Why use isolation clips when z-bar does the trick?” There is after all a cost to buying the clips and their profile adds thickness to the overall assembly. One answer is reliability. If the installer is not careful with resilient furring channels it can be relatively easy to place a screw in the wrong location creating a hard connection from the drywall to one of the studs making their installation moot. The acoustic experts at BKL have written an excellent article on the risks of resilient channel installation.
Although reliability is a compelling reason an experienced contractor can take precautions to avoid the short circuiting of the resilient channels. So what else can an isolation clip offer that the resilient channels cannot? The simple answer is performance.
Sound clips outperform resilient channels with higher STC values in testing, particularly at lower and higher frequencies (see below for STC definition). Lower, or “bass” frequencies are much harder to mitigate than high frequencies which is why in an apartment building you will only hear the bass from your neighbor’s house party. If you are considering building rooms that will need to contain low frequencies from music or movies we highly recommend the use of sound isolation clips over the resilient channels. A typical consumer level subwoofer has a range of 20 Hz to 200Hz and this is precisely the range where the clips drastically outperform resilient channels. In testing on walls built with one layer of 16mm drywall, wood studs 16″ O.C., fibreglass insulation in the cavity and the clips or channel carrying another single layer of 16mm drywall, the transmission loss numbers in the bass frequency range came in around 10 dB higher for the Regupol SonusClip over the resilient channels. The superior performance in these troublesome frequencies will sound like half the sound level to the listener on the other side of the wall. The important difference to compare is that between a happy and an unhappy client.
Regupol SonusClip sound isolation clips have been tested and approved under 40+ UL designs for US and Canada. Vibra-Sonic has them in stock at our Burnaby warehouse and ready to ship for your next project.
Sound Transmission Class (STC) – A numerical rating that describes how well a building element reduces airborne sound. It is used for interior walls, floor-ceiling assemblies, windows, doors, and exterior wall assemblies.
References for Graph:
Intertek report no: H7676.03-113-11-R2 (SonusClip)
National Research Council Canada test no. TL-93-118 (resilient channels)