A. Have you ever lived in a multi-story house or on the bottom floor of an apartment complex? If so, you know how bothersome it can be to hear your upstairs neighbors throughout the day. A high-scoring IIC floor rating is crucial because it limits the level of impact noises that reach lower levels, resulting in a more comfortable and tolerable lifestyle. 

     A. The Delta IIC rating shows what the product adds to the assembly in terms of isolating impact footfall noise. The Delta IIC test starts by testing a full assembly, typically six to eight inches of concrete, with nothing above or below the concrete. Then an underlayment installs directly to the concrete, and the same test repeats. The Delta IIC rating is the performance gain between the first and second test. A higher number shows better performance.

The Delta IIC rating is the best rating to consider when comparing the performance of different types of underlayment. It keeps the manufacturers from promoting misleading results obtained by using materials or methods of isolation that the average assembly does not use. Misleading results are most often found with claims of 60 IIC or above using materials less than 1/2” thick. They achieve their astronomical rating with decoupled ceilings and considerable additional mass, but will claim their thin underlayment is what achieved that IIC rating. If the IIC rating is unreasonably high, then ask to see a Delta IIC rating. If they cannot provide a Delta IIC rating, then ignore the advertised ratings.

      A No matter the type of flooring you have, the best way to improve your floor assembly’s IIC rating is by adding a flooring underlayment. A floor underlayment is a  layer of material (Fiber, Rubber, Urethane)  you place between the subfloor and surface layer. These underlayments  are  dense material that is naturally excellent at absorbing impact noises, making it a reliable option to use when trying to improve your floor’s IIC.