I am adding a second layer of 5/8 plywood to my existing 1/2 plywood subfloor, before installing hardwood throughout the main level. This is in order to match elevations with the kitchen and “beef up” the thin 1/2 plywood subfloor.

I bought 12 sheets of Plytanium 19/32 CAT PS1-09 Square Structural Plywood Pine from Lowes. All sheets were taken from the same stack and stamped as one pallet on the side.

I cut and secured three sheets in the foyer without any problems, when I moved into the adjacent dining room I started noticing large variations in thickness (up to 1/8”) from board to another placed next to eachother. A flooring contractor recommended shimming up the low boards so that they are flush and uniform. I am investigating other (more consistent thickness) plywood sources.

Any feedback or advice is appreciated