[Shop-talk] Floor repair

[Peter J. Thomas]

On 12/8/2015 9:11 PM, Robert nogueira wrote:
> I've got a little section of a floor which is spongy. The floor is 3/4"
> plywood with a over lay of 1/4" plywood all on 16 inch centers.  The bad
> section is small and only between two joists. My plan was to cut out the bad
> section between the joists and replace it with new plywood. My question, is
> plywood stiffer between two joists  if a sheet spans several joists or will my
> plan of one piece spanning between two joists be as stiff as a full sheet
> spanning several joists?
> Also, is plywood stiffer across its width or stiffer across its length
> I hope this all makes sense .
> Bob
I prefer to span at least three joints, it basically doubles the 
stiffness.  Adding 2x4 cross bridging between joints also helps.

Plywood is slightly stiffer along the length, but only slightly.