Print Page

Acoustic Panels for Apartments to Reduce Noise

Noisy Upstairs Neighbors

One of the increasingly frequent complaints by apartment, town home, and condo dwellers is unwanted noise from loud upstairs neighbors in the unit above. The noise intrusion can be characterized as either impact noise or airborne noise and too frequently, both.

Impact noise can be defined as the impact of footfalls or other movements from above, while airborne noise is noise that penetrates the floor/ ceiling assembly such as voices or music. In some cases, the sound may also be structure-borne sound transmission where the sound wave transmits through the structure.

Unfortunately, there is no easy or cost-effective fix for these problems with loud upstairs neighbors especially when the source of the unwanted noise is right above a home theater or recording studio. Since the impact noise is being generated from above, the upstairs occupant may not be under any obligation to install materials that would reduce the annoyance. Rest assured that the only effective way to reduce the noise pollution from above is to start addressing the problem in the source room, that is to say, upstairs.

Only if the downstairs occupant is sufficiently disturbed by excessive noise intrusion, can that occupant seek help under local noise ordinances or the right to peace and quiet. In the case of an apartment dweller, noisy neighbors above may be a lease breaker. A call to the local building inspection department to ascertain if a certificate of occupancy was issued to see if appropriate sound isolation measures were undertaken and validated can help.

All newly constructed modern day multifamily dwelling units are required, by building code, to be built to provide a minimum measure of acoustical privacy or isolation. The building codes require a single number rating for walls and floor/ceiling assemblies. A single number rating is based on laboratory tests called Sound Transmission Class (STC); the higher the STC number, the greater the airborne sound isolation to provide airborne sound isolation. The building code also states that while the STCs of the construction assemblies must be a minimum of 50 STC by design it will also pass if an actual measured field test of 45 (FSTC) is achieved. This is also true of the impact requirements for floor/ceiling assemblies, Impact Isolation Class (IIC & FIIC). The difference of 5 points represents the difference between an idealized lab test and an actual on site field test.

Unfortunately, the designing architect may select a wall and floor/ceiling assembly that meets the minimum building code criteria of 50 STC and IIC or greater but then takes no measures to insure that the minimum requirements are met in every detail. Furthermore, far too few local building inspection departments insist that field tests be conducted to validate that the appropriate sound isolation measures have been actually met, before a certificate of occupancy is issued, certifying the dwelling is in compliance with the building code.

Architects may specify STC/IIC ratings of walls and floors but then neglect to specify and design measures to prevent ‘flanking’ sound transmission pathways. Flanking sound transmission pathways are pathways that can let outside noise snake around the main wall or floor or even under the floor/ceiling assembly.

Lack of caulking, blocking, or other appropriate care to prevent flanking sound transmission can reduce the FSTC significantly. A 1/16″ crack at the floor line can reduce a 50 STC wall design to a 39, well below the minimum code requirement of a 45 FSTC. This would suggest that a few pennies worth of appropriate acoustical caulk sealant could be an ounce of prevention that will save reputations and possibly avoid post-construction litigation.

Floor/ceiling assemblies can be a little more problematic. For instance, a new dwelling may be constructed to include carpeting, which will provide a high degree of impact isolation. Later on, the upstairs neighbor may switch the flooring to a hardwood floor, thereby reducing the sound isolation characteristics of the floor/ceiling assembly. Unless the upstairs neighbor is willing to install an acoustic panel or a sound-isolating flooring underlay to maintain the appropriate sound isolation the downstairs neighbor is bound to be victimized by intrusive noise. Make sure external noise control measures are included in the owner’s association’s regulations where such associations exist.

[There are no cost-effective ways of improving the sound transmission of airborne or impact noise from the underside of the ceiling/floor assembly. It must originate with the floor above.]

Many old industrial buildings are being converted to Loft Type Condominiums where the old concrete floors are left exposed both as a finished ceiling below. Underlayments and concrete or gypcrete-type toppings can do a great deal to reduce the impact and airborne noise. However, the new buyer should get in writing a guarantee that the floors and party walls will meet minimum building code requirements. As an added precaution, a prospective buyer should conduct his/her own evaluation. Having a friend initiate impact sounds of the floor above can do this; in addition airborne noise testing can be accomplished by playing a radio in the space above or impacting on the floor, which can spot any glaring sound isolation deficiencies.

It is also wise to check the town home or condo owner’s association regulations to see what if any rules exist with respect to noise control. If a unit is carpeted and the owner elects to change to floor finish to a ceramic tile or hardwood finish, adequate measures should be taken to maintain the same impact isolation as the original carpeting.

When problems exist, sadly, there is no easy fix. The recommended solution is to add noise reduction underlayment to the floor above. The next step may be to remove the ceiling below and make sure the underside is insulated. In the case of wood joist construction a resilient channel applied to the underside of the joists before re-applying the gypsum wall paneling can be a big bang for the buck. That said, the floor ceiling assembly must be absolutely airtight in order to achieve maximum acoustical performance.
[Note: simply adding barrier materials or additional layers of gypsum board will only produce minimal improvements that will not justify the cost. For example, adding a resilient channel to an existing wall or ceiling may not achieve any improvement at all and can actually end up being worse than before the addition.]

Evaluating Your Prospective New Dwelling

  • Ask the builder what STC and IIC design criteria were selected for the walls and floors.

  • Conduct your own tour with a radio that can be used to check the sound transmission through walls and floors.

  • Have a friend impact on the floor above.

  • Check the plumbing noise, particularly in the bathrooms.

  • Check the impact noise from cabinets especially in the kitchen.

  • Check any window noises from highway or local traffic.

  • Check the relationship of your unit to any elevators or garbage chutes.

  • Check entry doors for sound seals and or automatic bottom seals.

  • Are the entry doors solid cores? Are the hallways noisy?

  • Are you on a flight path?

  • If your new proposed dwelling is hard surfaced in nature (i.e. walls floors and ceiling) and your furnishings are less than plush or upholstered; the space maybe highly reverberant which will lead to a noise build up of any sounds generated. In addition excessive reverberation may make speech intelligibility from conversation and TV watching difficult.

  • Look and Listen. Believe your ears. Take notes.

  • Your investment in a new dwelling may be one of the most expensive ones you’ll make, be sure you will be comfortable.

When all is said and done, and as previously stated, that there is no easy fix to solving noise problems from above, the best solution is to bite the bullet and prepare to invest in a soundproofing solution that is likely to end up to your satisfaction.


A common complaint expressed by many apartment, town home or condominium dwellers is that they can hear their neighbors next door. Sadly, there is no easy fix in most cases. The problems range from being able to hear voices, loud music, the TV or the bang of cabinet doors. In other cases it might be noise generated in the bathroom.

If the dwelling is a new one, the first order of business would be to consult with the builder. Multi-family dwellings are required to meet isolation standards in accordance with the Building Code. In the case of a party wall separating two dwellings, the code requires a wall with a minimum of a 50 STC (Sound Transmission Class). Unfortunately, many building inspection departments do not require validation by actual measurement and while the designing architect may specify a 50 STC or greater, there is little or no on site inspection to insure that good noise control techniques are followed by the drywall subcontractor.

The building code also states that while a 50 STC wall by design is required the same wall will pass inspection with a measured field test that results in an FSTC of 45.The only sure way to know what measure of acoustical performance the party wall will offer in terms of sound isolation is to conduct a test in accordance with an ASTM standard test protocol.

If you are unfortunate enough to be confronted with noise from your neighbors in a newly constructed dwelling, the first order of business is to contact the builder and your local building inspection department. The latter should be put on notice in that the building inspection department is required to provide a Certificate of Occupancy, certifying the building has been built according to code.

Before you confront the builder you can conduct your own investigation just by looking and listening. When you are listening for noise intrusion it can be very directional. You may have to get down on your hands and knees to listen for the sound. Listen also to other areas of the offending wall, such as plumbing pipes in the bathroom, make a list if you detect sound intrusion in order to give the builder some indication of the noise sources.

One of the most frequent sources of sound leakage through a party wall is through the base. Drywall installers have nasty habit of jacking the drywall up tight to the ceiling where the joint between the wall and ceiling will be visible. In doing so a void may be left at the floor which eventually will be covered by a base board. If the void at the base of the wall is not caulked; this can be source of sound leakage. Fortunately, this problem can be an easy one to detect and fix.

Listening to sound at the base may indicate a problem, then one can insert a flexible probe under the baseboard; if it goes in more than the thickness of the base board (about 3/8″) and comes out clean, this would suggest that the drywall was not sealed. In order to achieve maximum sound isolation the wall must be absolutely airtight.

The importance of a wall being airtight is demonstrated by a wall 9′ high and 10′ long. With a 1/16″ crack at the bottom; this crack represents 6/1000 of a percent of the total wall area, yet it will reduce a 50 STC wall to a 39 STC which, is below the minimum building code requirement. Caulking is the acoustician’s best friend and its application where necessary can be considered “an ounce of prevention”, but only if you know why.


From the gap we can see that even a small crack can significantly compromise the sound isolation performance of a wall, floor/ceiling assembly to be as airtight as possible. Caulking compounds or acoustical sealants are indispensable for effective noise control.
If the transmission of noise seems to be coming through the party walls and the problem does not appear to be a lack of adequate caulking, it is wise to check with the builder to ascertain if the wall construction will provide an adequate STC rating. If not, it maybe necessary to bite the bullet, and if possible remove the gypsum board on one side of the wall and start over again to insure the wall is insulated and to install staggered studs or install resilient channels to isolate the wall from one side to the other. Resilient channels or resilient clips are a good bang for the buck.

When contemplating purchasing, leasing or renting a residential unit, similar testing can be undertaken as noted for floor/ceiling assemblies above. In addition however, check for plumbing and airborne noises in both the bathroom and the kitchen. Since kitchens are frequently located back to back, check also impact noise from the kitchen cabinets. While kitchen wall surfaces should be isolated from one another, sometimes the surfaces will be bridged thereby short circuiting the sound isolation characteristics. Also check out traffic noise through the window units.

Adding another layer of gypsum board to an existing wall, for example, is likely to only produce an improvement of 1 STC point which is a very cost ineffective and undetectable measure. To produce a detectable improvement, major modifications may be necessary.