Replacing part of an old subfloor in a kitchen due to water damage. Old floor is 1x6 wood slats with plywood on top. Is there any benefit to replacing with slats again? I can't think of any myself, and would replace with T&G plywood. Slats vs. plywood vs. OSB to replace the slats, then another layer of plywood on top of that. I don't know that full thickness of the slat layer plus plywood layer, but if it is 1 1/4" total, I suppose a single thick layer of plywood could replace the slats plus plywood that's being replaced. (The final surface will be tile, so Ditra or cement board will be the top layer.)