Whether it’s a noisy neighbor to your apartment or you’re trying to mitigate noise from one area of your home to another, residential soundproofing can be a tricky application. Many homeowners and renters aiming to reduce noise are looking for an easy, affordable solution that can be installed over existing surfaces. Residential soundproofing however, for proper application to achieve the results people desire, it often requires structural remodeling to allow for acoustical product installation. In our experience this has made acoustical treatment cost prohibitive for the general resident.
Prior to any extensive-modeling, or addition of acoustical materials, there are a number of common-sense actions that can be undertaken to make the situation better.
Most important is to seal up any leaks or gaps that exist in the current partition, be it ceiling, wall or floor. Noise is like water in that it will find any leaks or gaps and infiltrate into spaces where it is unwanted. Sometimes these leaks or gaps are not apparent. Back-to-back electrical boxes can be an unknown source of noise leaks. Pipe chases, or enclosures where piping or electrical are contained often bridge multiple areas and can leak noise. Finally, doors are often a significant leak of noise between spaces. Even heavy solid doors often have a significant gap at the threshold and around the head and jambs. At the very least, thermal insulation seals can cut down on much of the sound leaking through.
Moving forward, we’ll discuss the basics of soundproofing a space and will address floors, walls, and ceilings individually.
Probably the most common complaint in multi-family residential settings is the sound of the upstairs neighbor walking or running, or moving furniture, infiltrating into the space below. While often-times it is airborne sound (voices, television, radio, etc.) most often the culprit is impact sound due to footfall. The guiding factors for the acoustical performance for a floor / ceiling assembly are based on STC (Sound Transmission Coefficient) and IIC (Impact Isolation Class). HUD categorizes both ratings to be a minimum of 50. (See education page regarding STC and IIC)
Ultimately, an acoustically correct floor / ceiling assembly will incorporate aspects of both treatments. Of course, in rental units, or short-term condo housing, undertaking major construction to the floor/ceiling assembly is often cost prohibitive. Some common-sense approaches to help resolve the issue is to have the upstairs neighbor invest in some carpeting. As stated earlier, a layer of carpet does often resolve IIC issues. Even throw-rugs or strategically located remnant pieces can make a difference with the noise perceived in the lower unit.
A relatively simple way to increase mass (and STC rating) is to have a layer of the mass-loaded vinyl noise barrier installed on the existing ceiling, and then putting another layer of drywall over it. This does a decent job of adding mass and increasing the assembly’s resistance to sound transmission.
The second most common complaint (and probably the easiest to avoid during initial construction) is ability to hear your neighbor next door through the wall. As with floor / ceiling assemblies, there is a HUD (Housing and Urban Development) code for the acoustical rating of a demising wall.
The most important rating of a partition is it’s STC (Sound Transmission Coefficient) rating. This is a measure of how much sound a single material or assembly will stop. In typical construction, a standard 3 5/8” metal stud with a 5/8” layer of drywall on each side has an STC rating of approximately 40. The same assembly using wood 2 x 4’s has a slightly higher STC of about 42-44. Both are below the HUD recommended number of 50. The result of this type of construction is that normal conversation is easily understood on the opposite side of the partition. The addition of thermal insulation to the cavity between the studs will yield another 3-4 dB on the STC rating.
There are several ways to increase the STC rating of the partition during construction.
When building the partition, instead of 2 x 4 studs aligned on a 2 x 4 floor plate, it is recommended that the construction be 2 x 4 studs on a 2 x 56 floor plate with every other stud being on an opposite side of the 2 x 6 floor plate. In this configuration, the drywall on one side is contacting only the studs on one side of the floor plate. While it’s not truly de-coupled, it is fastened to an independent set of studs. This configuration will yield an STC rating of approximately 46. Adding thermal insulation to the cavity will increase the STC rating 3-4 dB as well.
The next level of STC rating is to create two independent walls with a minimum 3” airspace in between. This configuration depends on creating two independent and separate masses. Typical STC rating of this assembly will be 54-56. Again, thermal insulation will add 3-4 dB to the rating as well.
There are several other things that can be done to increase the STC rating of a partition besides a simple construction method change. Other materials that can help are resilient channel, Resilient Isolation Clips, Mass-Loaded Vinyl Noised Barrier.
Resilient channel is a method of de-coupling the mass of the drywall from the structure of the wall itself. It can be used in single, double, or staggered stud assemblies. Special care must be taken when using resilient channel to not “short-circuit” the assembly by screwing through the resilient channel into the studs beneath. When installed properly, resilient channel will yield an additional 6-10 dB over the STC rating a standard stud wall. Another method that can be just as effective (if not more so) is to use Resilient Isolation Clips.
Resilient Isolation Clips
A Resilient Isolation Clip is also designed to de-couple the mass of the drywall from the underlying supporting structure. The unique shape of the clip works in a way that the clip is screwed to the structure and is shaped to accept a typical hat channel. The drywall layers are then screwed to the hat channel, for a fool-proof installation. The spacing of the clips is predicated on the number and thickness of the layers of drywall. As with other methods of increasing STC, thermal insulation in the cavity will enhance performance. A standard wood stud construction wall, with the addition of Resilient Isolation Clips and hat channel will yield an STC rating of 56.
This assembly can also be used with a layer of mass-loaded vinyl being added between the layers of drywall.
Mass Loaded Vinyl
Mass Loaded vinyl is an acoustical material that is used in many ways. For residential soundproofing, it’s most common use is as an underlayment for the drywall in a demising wall. During new construction, it is screwed to the structure (studs) prior to the installation of the drywall. This method is different from the vibration isolation method of the resilient channel or Resilient Isolation Clips. The barrier is not a resilient layer of material designed to isolate the drywall from the structure. It is a method of adding mass to the wall in a differing thickness and density than the material that will be put over it.
Does DDS Provide any residential soundproofing services?
At DDS Acoustical Specialties we are happy to assist homeowners and property owners make acoustical improvements. Depending on the need, cost for our acoustical products could range from $2,000 up to $15,000.
Examples of applicable residential projects include:
- New Housing Development
- Housing Redevelopment
- Home theaters
- Sensory Rooms
Typical products for new or redevelopment residential projects include noise barrier under sheetrock and floor underlayment. In some retrofit cases we may also recommend acoustic wall or ceiling panels.
Challenges of Residential Soundproofing
As mentioned, Residential Soundproofing comes with a variety of challenges – cost, accessibility, ownership, etc.
Apartments for example where a resident has noisy upstairs neighbor, this is considered impact noise. The solution to mitigate impact noise would be to treat the flooring of the above apartment with proper acoustic underlayment. This poses a challenge because the resident cannot access the above apartment or even make modifications because they do not have ownership. Some may think that acoustic ceiling panels would solve this issue but that is not the case. However, we are happy to work with landlords and property owners who are interested in making acoustic improvements for their tenants.