Bathroom floor tile

I have removed the old tile from my bathroom and am left with a wood floor. Even though I've gone over the floor to make sure it's solid, I'm considering just pulling it up and replacing it with Hardiebacker or some other new substrate. Is this necessary or even advisable. I've done other bathroom and utility room floors in this house but they were all on concrete substrates with which I've had no problems. Not sure I trust the original floor in this bathroom though. Thanks, Tom

Wood floor? Meaning plywood? Single layer as in you are at the subfloor or is it an underlayment layer on top of the subfloor and if so, how thick.

Maybe you should pull it, maybe you NEED to pull it, maybe you could leave it before installing a cement board or tile membrane of choice. We could give you a better idea after you respond with a bit more info. Also, did you plan to use tile or stone?

It is single layer, 1/2" plywood nailed to the joists below (bathroom is on second floor). I am planning to use tile on the floor. Thanks, Tom