When we were framing, we were >required< use 2" staples to shoot down
1/2" plywood deck. Having pulled enough of that stuff up, the 2"
staples hold well, and the shorter you get, you get much less holding
power. Besides, the cost between sizes when you get the larger sizes
This assumes that you are using a narrow crown stapler, not a wide
I always use the old shopworn formula that I learned years ago, and
that is to pick a length of fastener that is approximately 3 times
longer than the thickness of material you are fastening. So in this
case, the plywood would be 1/2" thick, times three, or 1 1/2". Add
back in the original material, and you have a fastener length of 2".
Remember the coating isn't always some kind of cool adhesive (check
the country of origin) that sets up with the heat of application, but
anymore it seems to be just a binder for the staples unless it is the
tiny 18 ga. guys.
I would get the longest staples I could, with divergent chisel points,
and when assembling shoot the staples so the crown was perpindicular
to the grain, not parallel. You could use shorter staples with glue,
but why take the time?
As always, YMMV.