Insulating for Sound


Today’s lifestyle is often a loud one. Modern appliances and amenities coupled with today’s high ceilings, hardwood floors, and air tight structures help create beautiful indoor environments, but also contribute to noise levels that impact a family’s quality of life. Improving your home’s acoustic comfort with acoustic—or sound—insulation can reduce stress and improve overall health and wellness.


Noise can affect family health

Throughout dozens of studies, noise has been clearly identified as an important cause of physical and psychological stress—and stress has been directly linked with many common health problems. That means that noise can be associated with many of these disabilities and diseases, which include heart disease, high blood pressure, headaches, fatigue, and irritability.[i]

[i] U.S. EPA, Office of Noise Abatement and Control, “Noise: A Health Problem,” p.23


What does insulation do for noise?

Sound insulation is one of the best ‘quieting’ technologies available. Insulation installed in the walls and floors between rooms absorbs the transfer of noise from one room to another, reducing the level of sound heard in one room from another. A good noise control insulation package not only increases the comfort of your home, but also adds to its value. In fact, one of the most economical ways to improve the acoustic comfort of your home is to install fiberglass, rock wool, or slag wool (collectively known as mineral fiber) acoustic insulation—at the time of construction, if possible.


Understanding sound transmission

The Sound Transmission Class (STC) is a single number rating used to indicate the effectiveness of an entire construction assembly (partition, wall, floor/ceiling) in resisting the passage of airborne sound. The higher the STC rating, the better the sound insulation performance of the construction. The 2015 National Building Code (NBC) requires a minimum ASTC 47 performance, which takes into account both direct and indirect noise transmission paths (flanking paths).


STC Speech Heard Through Wall or Floor
25 Normal speech understandable
30 Loud speech understandable
40 Loud speech audible as murmur, but intelligible
50 Loud speech barely audible
55+ Loud speech not heard


Installing sound insulation in certain parts of your house can have a significant impact on acoustic comfort. Key areas for insulation include:

  • Exterior walls
  • Interior walls
  • Floor Assemblies
  • Ducts
Exterior walls:

Exterior walls should be constructed with resilient channels and mineral fiber insulation filling the stud activity. Ensuring a continuous airtight air barrier system will enhance occupant comfort, reduce energy consumption, and will also improve the acoustical performance of the assembly.

Interior walls:

All interior walls and floor assemblies between living spaces should have an STC rating of at least 50. The basic guideline for installing insulation in wall and floor cavities is to fit the ends of the batts snugly against the top, sides, and bottom framing.


Duct design should be given special consideration when planning a home’s layout since ducts can easily transmit sound. Installation of sheet metal ducts, lined with sound-attenuating duct liner insulation, or using fiberglass duct board systems will reduce transmission of unwanted sound, including fan noise through the duct. Sealing the joints in the duct system will also improve the acoustic performance and energy savings.

Best practices for sound control

There are best practices for sound insulation that you and your insulation contractor or builder should follow for optimal results.

Achieve Optimum Acoustical Performance in Your Home

Apply the three basic principles to minimize sound transmission:

  1. Block the vibration path (use multiple layers of thick gypsum board on either side of the wall assemblies)
  2. Break or isolate the vibration path (using resilient channels, double stud walls, or staggered stud walls)
  3. Absorb the sound energy by filling the cavity with acoustic insulation

All partition walls, floors, and ceilings should have a minimum STC rating of 50 (walls and floors) and a minimum impact insulation class (IIC) 50 (floors). Avoid rigid connections to adjacent walls and use insulation and resilient floor treatments (i.e., carpeting and padding) to minimise flanking transmission through floor and ceiling assemblies. The 2015 NBC lays out prescriptive solutions to meet the minimum ASTC 47 performance requirement.

Solutions for acoustic comfort

An easy and economical method for increasing the sound transmission loss of a wall is to install sound absorbing acoustic insulation in the wall cavity. Installing mineral fiber insulation batts between rooms such as bedrooms and adjoining bathrooms, or between a recreation room and a den or study, will keep the noise level down between rooms.

Get The Quiet Home Checklist

Improving your home’s acoustic comfort with acoustic or sound insulation can reduce stress and improve overall health and wellness. Are you doing everything you can to make sure your home is properly insulated?


  • Fill all floor and wall cavities with mineral fiber acoustic insulation.
  • Insulate heating and air conditioning ducts by using fiberglass flex ducts, fiberglass duct board, or by wrapping or lining the ducts with fiberglass insulation.
  • Install resilient underlayments (carpeting and padding) throughout your home to help reduce impact sound transmission.
  • Install resilient mats between subfloor and finished floor to help reduce impact sound.
  • Caulk around windows and use weather-stripping at the bottom of your exterior doors.
  • Use solid wood or mineral core doors with insulation where privacy is required.
  • Install acoustic ceiling panels.
  • Reduce sound transmission with double or triple pane glass and storm windows.
  • Select quiet, high quality appliances.
  • Install telephones, doorbells, intercoms, or audio built-ins on interior walls only—never on common walls or corridor walls.
  • Caulk holes made by wiring that penetrates connecting structures with elastic non-hardening caulk or dry packing.
  • Seal openings around ceiling fixtures so that they are airtight.
  • Make use of plants, draperies, and wall hangings throughout your home. The “soft” objects in a room may absorb more sound.
  • Minimize window sizes facing noisy areas.
  • Ask your builder to develop a well-planned layout to minimize the noise of flowing water, and insulate walls containing drainpipes.
  • Ask your builder to seal under all bottom plates as the walls are being built.
  • Ask your builder to avoid undercutting doors, if possible. Frequently, doors must be undercut to get proper air circulation for the HVAC. A simpler solution to ensure proper circulation is to keep doors open when rooms are not in use or provide transfer registers.