The Impact Insulation Class (IIC) is a numerical value which indicates how well a floor/ceiling assembly can restrict the flow of impact sound energy from one space to another. The higher the IIC number, the better the floor/ceiling assembly is at restricting the flow of impact sound energy between the adjoining spaces.​

The IIC testing is performed by generating impact sound energy using a tapping machine. By striking the floor above, this tapper creates calibrated vibrations that travel down through the floor/ceiling assembly. The impact sound energy is then measured by equipment placed in the space below. Based on the collected test information, we are able to calculate the numerical IIC rating of the floor/ceiling assembly.​

For multi-family properties covered by the Florida Building Code – Building Edition, a minimum IIC rating of 50 is required for the design of the assembly, and a field-tested assembly must achieve a minimum IIC rating of 45. A field IIC test can determine if the installed assembly complies with the referenced Code provisions.​