I am about to put 5/8" plywood onto a subfloor. The subfloor is not level.?

Question

Should I use the SLC before I put the 5/8" plywood down or should I lay the plywood and then level the floor??

Answer 1

what are you going to put on the ply?....5/8 ply is too thin   give us more info

Answer 2

Do you mean not level or not flat?  

Levelness is of little consequence usually, unless it's under a tub or something that must be level.  

You can use shims or layers of builders felt to even out any "not flat" areas in between the subfloor and the plywood.

Answer 3

Always level the floor first........then you start out correctly.....just that simple........everything else turns out good that way.

Answer 4

If you have a masonry subfloor existing you don't lay plywood over it.  You use SLC and if the grade is drastic you want to use "Ardex Brand" SLC, not the products available at the home centers.

Be more definitive on this project and I'll be willing to walk you through the proper methods and procedures to achieve "professional" results.

Chopsaw. . .  Good Answer!!!

Answer 5

Put the plywood down and then the floor leveler.  It would be much harder to ship the joists before laying the plywood.  The floor leveler will also help by filling in the seems between the sheets of plywood.