Well, I hated the saggy 3/8 inch plywood that was OEM, so I got 1/2 inch (actually 15/32 I think) and it took two panels to cut appropriate pieces that where the joint direction was not the same as the existing. I got a tube of construction-grade liquid nails and a box of screws. After I was done, the overall thickness is about 3/4 inch. This is more rigid than OEM for sure; however if you want to completely eliminate the flexing when you sit on the edge of the mattress, you probably should make a floor-to-plywood support out of a 2x2 board. My wife wants me to make a prop to get stuff out of storage under the bed.