How to Control
Sound Transmission
Through Floors
Reducing sound transmission through
floors and ceilings is much more difficult
than controlling sound on the same
level. The builder faces all the problems
of airborne-sound control, plus the
problem of structure-borne impact
noise. The expression "waiting for the
other shoe to drop" must have been
coined by an apartment dweller in a
building with poor floor construction.
How Much Isolation Do
We Need?
A building component's ability to
resist sound transmission is rated by
Sound Transmission Class. (For a full
explanation of STC, see "The ABCs of
STC Ratings," page 32.) For instance, a
floor-ceiling system with an STC of 35
could reduce a noise level of 75 decibels
(inside a moving car with