I am tiling a bedroom soon. I have already purchased the tile, but not anything else. There is currently oak hardwood that is incredibly water damaged beyond repair, so it will all be pulled up. The subfloor beneath it is plank.
I know that I will need to lay down concrete backerboard to lay the tile on. Do I also need to lay plywood or OSB down on top of the planks first? If so, which is better? I have to assume that plywood is better, but how bad is OSB? I want to do what is best and most structurally sound, but if there isn't that much of a difference I'd rather go with what's less expensive.
After you replace the hardwood, be prepare to repair or replace some of the subfloor. Re screw every plank using floor screws, no drywall screws. Although "subfloor" grade OSB is acceptable, I recommend and underlayment grade plywood. B/C grade should be easy to find. Install it fastening it only to the planks, not to the joists too. No glue should be used. Go as thick as you can, but no thinner than 1/2". The cheap OSB non t&g we see may not be acceptable, yet you may not want to use 3/4" thick OSB which is "subfloor" grade.
Next step is the tile backer or a product such as Ditra matting. I vote for Ditra.
There's obviously much more to it than what I just wrote, but those are the basics. What experience do you have? Are you installing ceramic/porcelain or something else? Are the joists stiff enough for your tiles? How old is your home?
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.