The floor of my laundry room was three layers of hideous vinyl flooring of various vintages, a layer of 3/4" plywood underlayment (to match the height of the vinyl to surrounding hardwood flooring) and a subfloor of diagonal 1x6ish planks.
I removed the vinyl and replaced the rotting plywood. Now I'll cover the plywood with interlocking vinyl plank flooring of this type. The instructions are written for covering an existing flooring material, so they don't address preparation of the subfloor.
Although the vinyl planks are waterproof, it doesn't seem right to lay them on bare plywood, particularly in the laundry room. How should the plywood be prepared? I think I'll just paint with Kilz 2 and caulk gaps and seams.
Best Answer
I'd question how waterproof you need this to be. Will there routinely be water sitting on the floor? If not, you may be over-engineering things.
That said, off the top of my head, one option for waterproofing the subfloor would be to paint on Redgard:
It's a 'paint on' waterproofing membrane that you'd typically use behind tiles on cement board and the like.