"Duane Bozarth" wrote in message
...
Leon wrote:

Perhaps...lacking data but recalling experience I suspect how much would
be species and type of construction (of the ply) would play a part.
Obviously if it sags a half-inch under immediate load it ain't
enough...a smaller deflection that might be judged acceptable initially
could easily end up w/ quite a bit more over time I believe.

IMHO a far better method would be to double up on the plywood and reinforce
with 3/4" solid wood around the perimeter. About 10 years ago I built an
Oak veneer plywood cabinet double thickness at 1.5" thick total with 3/4"
trim around the perimeter. Setting on top is an old Mitsubishi 35" tube
type TV. Weight approximately 200#'s. No sag at all.