Had to do it. Did like you and used treated plywood. It still rotted over time due to moisture from the sprinkler system. I bought three 2x6 and slid the shed off of the old plywood, poured a slab, slid it back and bolted it down. Still good six years later.
[Edit] PS: Mine was a Tough Shed so it held together fine.
Last edited by pug; 03/11/18 03:55 AM.