Quiet Buildings Retain Residents: IIC, STC, and Flooring Assemblies
Impact noise is one of the top three complaints in multi-story senior living. Here is how the flooring assembly drives the number.
IIC vs STC in plain terms
STC (Sound Transmission Class) rates airborne sound — voices, televisions, alarms. IIC (Impact Insulation Class) rates structure-borne sound — footsteps, walker legs, dropped objects. Flooring barely moves STC. Flooring is the single biggest lever on IIC.
Most senior living projects target IIC 50 as a code floor and IIC 55–60 as a livability target for units stacked above occupied space.
The assembly is the rating
A product does not have an IIC rating; an assembly does. The same LVP over a 6-inch concrete deck and over a wood-framed deck can differ by more than 15 points. Always request the tested assembly report, not a product data sheet number.
Attached-pad LVP typically buys 4–8 points over a hard-set install. A separate acoustic underlayment in the 2–3mm range typically buys more, at the cost of indentation resistance under point loads like bed casters and lift equipment.
Where the money is best spent
Second floor and above, resident units over dining or activity spaces, and any corridor directly above a bedroom. Ground-floor slab-on-grade areas rarely justify the added underlayment cost.
Specifying a senior living project right now?
Our free 8-page Builder's Guide covers safety, acoustics, infection control, and a 15-year cost of ownership model — with a room-by-room spec map.