- Q. Does tongue-and-groove
plywood add extra strength or stiffness to a floor system, or
does it just help prevent floor squeaks?
A. The tongue-and-groove
joint doesn’t add strength, but it does help to
distribute loads to adjacent panels, improving the perceived
stiffness of the floor. T&G plywood was developed as a
labor-saving alternative to installing solid wood blocking at
unsupported panel edges.
Without the tongue and groove, a load on one panel edge
causes that panel to deflect relative to the adjacent sheet. A
wood floor that spans across the joint would experience a
wedging action, causing a floor squeak. Tongue-and-groove
plywood is actually more effective than solid blocking at
preventing squeaks, because over time the blocking will shrink,
leaving unsupported edges.—S.M.