Do I need a plywood base to install granite countertops?
The answer to this seems pretty clear when you consider one thing: It takes a substantial amount of force to bend granite, but it only needs to move a few micrometers&ast; to break.

Now you just ask yourself whether a layer of plywood will prevent that miniscule movement. No, it won't. Physics has no interest in the opinion of the masses.

So, you might use a plywood substrate to help replicate a thicker top, or to reinforce poorly-built cabinets, or to help maintain position by adhering the stone to it, or for other practical reasons, but you don't do it to support, stiffen, or strengthen the stone. That would take something much more substantial and rigid, such as the vertical hardwood cabinet rails that typically exist at the front and rear of a cabinet.

&ast; Or a few dozen, or a few hundred. The result is the same.