Proper subfloor when you have hardwod over concrete!!
I am replacing the kitchen floor in my daughter's 1930's DC coop townhouse. The kitchen has hardwood floors which are sturdy, but the finish is ruined and water damaged. She wants to put down tile.
Now I know that Hardiback over hardwood is a no-no. But here's what we found. We pulled up one of the hardwood boards and underneath it is a concrete floor. (She is on the second floor.) The hardwood is not laying directly on the concrete which is quite rough. There are 1x2 (?) slats that appear to be fixed to the concrete, and the hardwood is nailed down perpendicular to the slats. The floor is perfectly level, but as I said earlier, the oak hardwood has shrunk, specially near the sink and dishwasher.
QUESTION: What should we do. My gut tells me we should rip out the hardwood and put down 3/4" ext ply over the slats, then thinset down 1/4" Hardiboard and finally the tiles.
Does this sound like a good idea? I don't want to cut corners, but I also don't want to do anything unnecessary.