This is a legacy version of the WELL Building Standard. Please check the latest version here.

Impact reducing flooring

Footfall noise from adjacent spaces can lead to occupant dissatisfaction. Constructing interiors to accommodate for footfall noise can greatly reduce its negative impact on acoustic comfort. In common spaces, especially corridors in open environments where there is heavy foot traffic, this feature minimizes disturbances. Footfall noise is characterized by impact insulation class (IIC). IIC of a particular floor assembly is determined from the use of a tapping machine, as described in ASTM Method E492; most flooring products also list the IIC in their specification sheets. The higher the IIC, the greater sound attenuation of impact sound. IIC measurements cover a frequency range of 100-350 Hz; the range corresponds to a general “thump” at the lower level, and a sharper “clack” at the higher end.

Part 1: Floor Construction

All floors in the corridors of all regularly occupied spaces have the following:

a.101 Impact Insulation Class (IIC) value of not less than 50.

Applicability Matrix

Commercial Kitchen Education Multifamily Residential Restaurant Retail
Part 1: Floor Construction - O O - -

Verification Methods Matrix

Letters of Assurance Annotated Documents On-Site Checks
PART 1 (Design)
Floor Construction

California Building Standards Commission. California Building Code. Published 2013. Accessed September 16, 2014.


California Building Code (2013) Title 24 Section 1207.3 states that the impact insulation coefficient (IIC) rating shall be not less than 50 for separate floor-ceiling assemblies when tested in accordance with ASTM E 492.