"calhoun" wrote
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.

Being _normal_ building grade sheets are 4'x8', it sure does make a
difference how it is installed.

Guess if you've never used the better grade of 4 ply compared to 3 ply, you
wouldn't see any difference.