Sound Insulation and Transmission


One of the most important elements of comfort within a home is the ability to close the door and have silence within the home. The problem with sound insulation and transmission is that no one thinks it is important when constructing the home. How many times have you heard anyone discuss the quietness of a home, or the techniques available to reduce sound transmission within the home?

Sound transmission is important within certain aspects of commercial construction, such as recording studios, academic applications such as lecture halls or court rooms or any special application where privacy is of ultimate importance. Very rarely does the element of sound transmission or special sound insulation become an important consideration within a home. Yet, isn’t peace and quiet one of the most important elements and positive attributes of any one’s home.

If the structure is new, then modern construction techniques and “ best practice “ methodology will result in a relatively quiet home. Modern windows and doors have inherent sound transmission levels that are substantially quieter than those of older homes. The degree of insulation within the exterior walls as well as roof and basement areas, required by the current code, will produce a home that is relatively quiet and protected from exterior ambient noise.

However, what are some of the additional steps that can be taken to enhance the “quietness “of the home, and provide a more private living space?

Listed below are a number of considerations that you should evaluate, if sound transmission within the home is important to you.

  • Ceiling insulation. Although most individuals immediately consider the walls as the primary transmission route for sound, the ceiling is extremely important. The installation of acoustical insulation in the walls will reduce the transmission of sound, however, the installation of acoustical insulation in the ceilings; will also significantly reduce sound transmission. Sound must be prevented from moving from one living area to the other. If the walls are properly insulated and there is not an easy transition for the sound to travel up and over the insulated walls, the sound barrier has been completed. If the sound can move up into the ceiling area and back into the adjacent space, then the sound isolation has been compromised. Think of the space as a contained space with no means of air to move from one space to another. If the area is sealed, then sound will be better prevented from permeating into the adjacent space.

 

  • Plastic barriers. The installation of a special plastic sound barrier in the walls and ceilings will further reduce the transmission of any sound. One of the primary techniques to stop sound waves from moving from one space to another is a heavy plastic barrier. There are several different products that are sold to reduce sound transmission from one room to the other, however, in the average residential home, the installation of a heavy mill, polyethylene barrier within the walls and over the ceiling will produce a similar effect. Remember that the placement of a plastic barrier between interior rooms is not as critical for reasons of water accumulation and mold creation as between hot and cold spaces, such as the roof, basement floor or exterior walls. We have discussed the effects of the improper placement of vapor barriers on the exterior walls or any spaces with dissimilar temperatures. Between interior areas that have the same environmental temperature or basically the interior walls, is not as critical.

 

  • Cast iron waste lines in lieu of PVC. There is a significant difference in the sound transmission of PVC piping as a waste line, in lieu of the old fashion cast iron waste lines. Most plumbers will prefer that you choose the typical PVC piping alternative to cast iron, for all the waste lines in your home. One of the negative characteristics of PVC piping is that it transmits the sound of water flushing and the flow of the liquid through the lines. If you are sensitive to sound within the home, then the use of cast iron piping for all of the waste lines will significantly reduce the sound of a flushing toilet within the home.

 

  • Special bathroom space acoustic insulation. The acoustic insulation of toilet room walls is more commonly a commercial consideration. However, the individual residential home bathroom spaces can also be acoustically sealed to provide additional private comfort within these areas of the home. In addition, the use of the bathrooms in the evening hours is common place, the more sound insulated these areas are, the less intrusive to the other inhabitants that maybe sleeping within the home.

 

  • Proper sealing. Sound transmission is reduced by the simple sealing of joints and openings between the rooms of a home. Sound waves are blocked by density, therefore, the more dense the material, the less sound is transmitted through the material. A solid concrete wall is more sound resistant than a drywall partition. However, even a concrete wall will transmit sound, if there are openings in the wall. The proper sealing of all opening, joints, cracks, etc. will reduce the transmission of sound no matter how dense the material maybe. Sound waves will find the open areas between spaces and travel easily between these areas, if not properly sealed.

 

  • Material density. The density of the material between rooms is important to the limitation of sound transmission. A simple drywall partition is far less resistant to sound transmission than a concrete partition or a solid block wall. The doubling of sheetrock, the introduction of sound insulation within the drywall partition will reduce the sound transmission factor.

 

  • Vibration reduction. Sound is vibrating sound waves, however, physical vibrations, such as those emitted from the dryer or washing machine will cause transmission between interior spaces. A water pump that is vibrating will produce a humming noise that will permeate the entire dwelling. How many times have you been in a hotel room that has a humming mechanical unit in the neighboring room? The humming is easily transmitted into your room. Sound transmission is enhanced by mechanical and physical vibration. Eliminating the vibration will reduce the ability of the sound transmission between spaces.

 

  • Space reduces sound transmission. The more distance between you and the sound, the less you will hear the sound. Although this is an obvious physical characteristic of sound, it can be used as a planning tool when deciding on the floor plan for your new home. The proper location of the bathrooms, the laundry room, the family room in relation to the bedrooms and living room areas, will make a big difference in the noise qualities and transmissions within the home. To place the open family room, with its television, stereo, or loud conversations, alongside all of the bedroom areas, will not enhance the “peace and quietness” of the home. Proper placement, in consideration of the intended use of each space, can, and will provide a quieter environment for the spaces more sensitive to noise, such as the bedrooms.

 

  • Masking sounds. The use of masking sounds is a commercial method of quieting or masking the sound transmission within a structure. Like the music in the doctor’s office, the use of a masking noise, such as quiet piano music, will cover up the sound transmission within the home. This can be accomplished with a basic sound system that is engineered for total home distribution.

 

  • Basic “best practice “construction. The use of best practice construction techniques within the home will enhance the “peace and quietness “of the home. Tight fitting doors, windows, walls and ceilings, will reduce the ability of sound to move from one space to the other. Quality construction will offer the best type of quietness within your home. The assurance that your contractor is professional and knowledgeable will provide the proper type of construction necessary to limit sound transmission within the home.

Sound transmission is basically a common sense issue. Think about how your voice is transmitted through an environment. If there is substantial structure in the way, you will not be heard, if there is an underlying sound, such as music playing, you will not be heard. If the spaces between you are substantial, your voice will not be heard.

Sound needs an open route to transmit, and the simple method of stopping that open route will reduce the sound transmission throughout your home.