Q: I have 60 yr. old wood floors that are totally shot. What is the best way to cover the existing floor (since I do not have sub flooring/ no subfloor under wood floor) with a new wood floor?
A: It sounds like the floor you are walking on may be a softwood that has been sanded a few times and which actually was the original sub floor. I have seen a few times where oak was installed directly on the joists too. You could secure the boards to eliminate movement and then install plywood over top, screwed into the joists, or elect to strip everything off and then screw down the 3/4 ply. Remember, the final finished floor will only be as solid as what it sits on, so make sure the new sub floor is secured well.