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Sound Control

Controlling airborne and impact sounds is as much of an art as it is a science. Soundproofing a room or structure requires as much attention to construction details as it does to the construction materials. Sound attenuation or absorption can be measured and assigned various ratings to demonstrate the level of effectiveness. The three most common rating systems are Sound Transmission Class (STC), Impact Insulation Class (IIC) and Noise Reduction Coefficient (NRC).

STC is a single-number rating of a material's or an assembly's ability to resist airborne sound transfer at the frequencies from 125 to 4000 Hz. The higher the STC rating the greater the sound absorption through a partition wall. Generally the code requires an STC of 50 through dwelling separations. This is rarely sufficient as loud conversations and moderate music levels can still be heard across the wall. Most quality builders will design and construct party walls to achieve an STC of 60 or more.

Insulation is of course an integral part of of achieving a suitable STC rating. However, not all insulation is created equal. Generally fibrous insulation works best, while rigid polystyrene or sprayed urethane achieve the least satisfaction. Due to its high density our insulation out performs most other insulation, including fibreglass - in excess of three times that of fibreglass batt insulation. This mass effect gives the insulation the ability to absorb lower frequencies such as those associated with traffic and airport noise. Since the STC rating does not capture all of these frequencies in its calculation, the mass effect of our product is rarely acknowledged. However, the effect is clearly noticeable especially if you live on a busy or heavily traveled street.

IIC is a single-number rating of how well a floor/ceiling assembly resists the transmission of structure-borne or impact noise, such as footsteps or a chair being dragged across the floor. It utilizes a tapping machine to generate sound frequencies. Unfortunately this does not accurately reflect "real world" impact sounds such as footsteps which generate lower frequency sounds. Although this rating system does not accurately take into account the mass effect of our product, you will clearly see an improvement.

Hammer Box - NRC Ottawa, Canada

Noise Reduction Coefficient (NRC) measures the sound absorption qualities of a material. It is calculated by averaging the material's sound absorption coefficients at frequencies of 250, 500, 1000, and 2000 Hz. An NRC of 0 indicates perfect reflection; an NRC of 1 indicates perfect absorption. This value is important as it relates to reverberation or echoing within a room or structure. By spraying 1" of our product on interior surfaces of a building you can expect a NRC value of 0.75. Please note that our spray product is not intended as an architectural product so it will require the application of a finish coat.