Tiling bathroom, need help with subfloor
This will be my first time tiling. I just removed the old tile from the bathroom, it's probably been there for 50 years. Most of it was no longer adhering to the subfloor which was plywood. When we stepped on the tile in bare feet the tiles would stick and pop off the floor...lol. So it's time.
Joists are 16" on center. I'm new to this stuff so bear with me.
When I look at the floor there are the joists, then on top of the joists are 1" thick planks about 7" wide, then on top of that there is about 1/4" plywood and then the tile.
My original plan was to remove tile, then lay Ditra on top of the existing plywood, but the plywood looks nasty. it smells and there is still adhesive on it. I guess I could sand it down.
What are my other options? I could rip up the plywood and just lay another clean new sheet of plywood and use the Ditra on top of that?
I could rip up the plywood and lay 1/4" sheets of cement backerboard?
I guess I could also lay backerboard on top of the existing plywood?
I've included a pic, it's a view down onto the floor, you see the plywood and then the 'planks' I mentioned. I just want to be sure I have a good sturdy subfloor for my tile.
Thanks for any help