- Q.In the search for a
bounce-free floor, does either solid blocking or
cross-bridging do anything to reduce the vibration
caused by foot traffic? I haven’t been able to
sense a difference between blocked or bridged floors
and those without blocking or bridging. Consequently, I
haven’t used either technique on my floor
systems for several years.
A.Frank Woeste,
P.E., and Dan Dolan, P.E., of Virginia Tech in
Blacksburg, respond: We actually evaluated the
effect of bridging or blocking on the vibrational
performance of solid-sawn joists and I-joists in
the laboratory. Full-scale floors were tested with
and without bridging or blocking installed. Based
on key indicators of floor performance, bridging
and blocking had only a minimal effect on reducing
annoying vibration. A much better way to control
floor vibration is to increase the depth of the
joist and limit the joist span, as described in our
article, "Beyond Code: Preventing Floor Vibration"
(Practical Engineering,
11/98).