"Josh" wrote in message
...

"Darro" wrote
Any other observations about the stiffest configuration of plywood
sheets under 5/8" thickness?

Darro

The local lumber yards here, sell 1/2" CDX with 3,4, & 5 ply. Five ply
will be your stiffest (and most expensive out of the 3 choices) plywood,
the
plys are alternated when glued/compressed together.

IMHO, stay away from 3 ply for any application except when hung vertically
for exterior walls.

4 ply? that would be strange, grain would run different front to back. Guess
it would make no dif if installed across the joists or parallel to them.
Don't see much straight dif from 3 ply.