Sound Control
Cellulose insulation provides very effective sound control to minimize outside noises and between rooms (if the interior walls are insulated). Many people only focus on the energy savings that can be achieved with cellulose insulation but overlook the benefits that come from improved sound insulation.
There are two measures of “sound” when talking about insulation:
- Noise Reduction Coefficient (NRC) which measures how much sound is reflected back into a room and
- Sound Transmission Class (STC) which measures how much sound is transmitted between spaces (i.e. rooms).
The Noise Reduction Coefficient (NRC) measures the build-up of noise within a space. A single number index rating is used to measure the absorption of a material. Our FIBER-LITE products have a NRC rating from .82 to .75 depending on wall design, materials and applied density of the product. Simply put, FTI’s cellulose insulation products will absorb 75% to 82% of the sound that it comes in contact with and will reflect 18% to 25% of the sound back into the space.
The Sound Transmission Class (STC) measures the sound transmission between spaces. A single number rating is used to measure the barrier effect. A higher STC rating blocks more noise from transmitting through a partition. Loud speech can be understood through an STC 30 wall but should not be audible through an STC 60 wall. Our products have an STC rating of 44 to 68 depending upon the wall construction. The STC rating is a lab test that does not take into consideration weak points, penetrations, or flanking paths.
Acoustic wall treatments with a high NRC can stop sound from reflecting back into the space and lowering the noise level within the space. Improving the STC rating of a wall (wall cavity insulation, etc.) will reduce the noise transfer to the adjacent space.
Companies using cellulose insulation in commercial applications, such as metal buildings, can notice a significant reduction in sound transmission due to the superior absorption properties of cellulose insulation.
