Frequently Asked Questions

Where can I get product specifications?
Each product’s main page has a downloadable PDF Specification Sheet, or feel free to call (800) 782-0070 or email ceilings@interiorsystems.com with questions.

What does Noise Reduction Coefficient (NRC) mean?
The NRC of an acoustical material is defined as the arithmetic average to the nearest multiple of 0.05 of sound absorption coefficients in four octave band frequencies of 250, 500, 1,000 and 2,000 Hertz. Basically the percentage of sound absorbed that hits the acoustical material.

What does Ceiling Attenuation Class (CAC) mean?
A two room method of testing establishes a standard reference for the attenuation or reduction of sound from one room to another. The higher the number the better a material is at stopping sound transmission between spaces.

What is the difference between fire-rated and Class ‘A’ non-combustible?
Class “A” or 0-25 flame spread index, is the rate at which fire will spread over the surface compared to asbestos board (0) and red oak (100). A fire rating is a test of the total system of roof/ceiling assembly, not just the ceiling. The rating is expressed in hours of protection to the structure prior to failure.