If your job-site plywood stack seems to be
shrinking when you’re not around, try screwing
it down, I use 3-in. drywall screws to connect
the top layers at the corners. The resulting
3-in. thick plywood slab is heavy enough
to discourage all but the most determined pilferers,
and your plywood and whatever lies
under it will stay put until needed.
Michael R. Sweem, Downey, CA