Resilient Channels, sometimes abbreviated as RC, are some of the most common components installed on projects requiring additional soundproofing (higher STC ratings). While they provide a significant improvement in decoupling the structure-borne noise in walls, they should not be seen as a panacea for all noise issues. Over the past 20 years, in both industrial and commercial settings, we’ve found resilient channels installed correctly in the field less often than not, resulting in poor acoustical performance. Below is a list of most common design and installation failures.
Common Mistakes with Resilient Channel
- Designing Resilient Channel for Metal Studs
The #1 benefit of RC is the ability to decouple structure-borne noise at a reasonable cost. This is an effective approach on wood stud or high-mass walls with a high stiffness index. However, a significant amount of commercial construction is completed with 20-gauge or 25-gauge steel studs, which already do an adequate job decoupling noise due to their intrinsic flexibility. The proper soundproofing method with these walls is to add mass via a soundproofing membrane or conventional construction materials, since additional decoupling will result in very little or no further improvement.
- Poor Installation Methods
The most common cause of failure of this system to meet performance specifications is lack of proper installation in the field. Resilient Channel is often installed by the same drywall hanging team that performs the rest of the drywall installation, in an effort to cut cost and reduce schedule. Without a professional that is very familiar with this, it is easy to run into the following issues.
- Drywall Screws Going Into Both Resilient Channel Flanges: This needs to be inspected after every sheet of drywall. The RC is designed to have one screw lock it into the stud, and another screw attaches the 2nd flange to the drywall. However, the channel is not visible when screwing in, so it is very difficult to attach the fasteners to the exact spot. If any of the screws go through to the inside flange, the Resilient Channel is now fully locked in, and provides no soundproofing benefit.
- Baseboards: When installing baseboards, many contractors place a wooden block to reinforce the bottom edge of the drywall. If this is done, the drywall is structurally locked to the studs, and the Resilient Channel is not effective.
- Hanging RC over existing drywall: When adding a 2nd layer of drywall, this should be done on the other side of the wall. If the resilient channel is installed directly over drywall (rather than studs), it creates a mass-air-mass condition that greatly reduces its effectiveness.
- Attaching Cabinets or Bookshelves
Although strong in compression, resilient channel is very weak in tension, and therefore should not be used on walls where heavy units will be mounted, such as TVs, cabinets, or bookshelves. These units will either pull away from the wall over time, or if directly mounted to the studs, will greatly reduce the effectiveness of the RC.
- Using RC in Tight Space Confinement
Finally, RC requires an extra 2” per room used, due to the thickness of the channel and the extra sheet of drywall. In restricted spaces, this often becomes a limiting factor, especially in renovations or small units.
Deciding on Resilient Channel vs. Soundproofing Membrane
Ultimately, every architect needs to determine their STC requirements and the most cost-effective way to meet them. As an acoustical consultant, we typically recommend Resilient Channel for gypsum ceiling assemblies under open web truss and concrete decks. Furthermore, we’ve found it to be quite effective on walls requiring 2-hour fire ratings that do NOT require heavy loads suspended on them (anything over 50 pounds). In hotel rooms or apartment complexes, adjoining walls should strongly consider a range of soundproofing membranes that best meets their needs, often at a significant cost reduction from resilient channel while still hitting higher dB losses.