Noise Ratings
Adams Stirling PLC


A decibel (dB) is the unit of measurement for sound intensity. Broadly, there are two types of sounds within a building: (i) Airborne Sounds, which are sounds transmitted though air, such as voices or radio playing, and (ii) Impact Sounds, which are created by an impact of an object with building elements or furnishings, such as footsteps, dropped objects, toys, furniture scraps, piping, and some appliance sounds.

  A 10 decibel increase means the sound is ten times louder. Prolonged exposure to noise louder than 85 decibels can impair hearing.
  Very painful 160 Shotgun  
  Painful 140 Stock car race  
    130 Jackhammer  
  Deafening 120 Rock concert  
    100 Chainsaw  
  Very loud 90 Hair dryer  
    80 Police whistle  
  Loud 70 Average radio  
    60 Normal conversation  
  Moderate 50 Average Office  
    40 Quiet radio  
  Faint 30 Whisper  
    20 Rustling leaves  
  Very faint 10 Soundproof room  
STC:   Sound Transmission Class. A laboratory measurement of the ability of walls and floors to mitigate airborne sounds including voice, television and alarm clocks.
NIC:   Noise Isolation Class. An over-all measure of the sound isolation between units in a multi-family dwelling. A field measurement of the ability floor/ceiling assembly to mitigate airborne sounds.
IIC:   Impact Insulation Class. IIC is a number rating for evaluating the impact noise insulation of a floor-ceiling assembly.
FIIC:   Field Impact Insulation Class. A field measurement, i.e., done after a hardwood floor installation is completed to test actual noise transmission into the unit below.

The higher the value, the greater the noise isolation. For example, an STC of 52 provides better sound protection than an STC of 45. Building codes typically require that floors provide an airborne sound insulation to meet an STC of 45 (field-tested) and an IIC of 45 (field tested) for impact noise. Note: local building codes may require higher standards.

Recommendation: Boards should establish noise standards for the installation of hard-surfaced flooring.

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Adams Stirling PLC