Recommended Floor Build-Up (Bathroom)

[albaPhenom]

Can anyone guide me with this one.

I currently have the original floor boards which are in good condition apart from a small section behind the original bath in the corner, I'll replace these with something else, these are fixed to joists t approx 400 centres.

What's recommended for a tiled floor build-up from this point forward. I'm getting caught between Youtube experts and the advice of people coming in to look at the project.

My thinking is that I want to be screwing something over the top of the floorboards, say a plywood to provide strength and take any flex out the floor, then on top of this a waterproofing tile backer board?

Then the tile adhesive and tile?

Is that right or am I doubling up here with both a ply and backer board?

Also, what would you recommend as a minimum tile thickness for a bathroom floor.

 

[Dewalt2003]

screw all floorboards down , so that floor is solid, then lay ditra matting/ Durabase over floorboards with flexible tile adhesive.
Then tile straight onto that. You will have no step at door thresh hold and a proper job.

 

[Dewalt2003]

Any floor tile will be fine, as long as its bedded down well.

 

[Suited72]

6mm ply, then important to prime it with a tile primer and then tile with an S2 tile adhesive - thats what we do. You had a suggestion for ditra matting which is also fine and can be used instead of S2 adhesive which is a similar method of decoupling and allowing for movement. I would still ply before the matting (3.4mm maybe?) but then the levels can get a bit high, so work with what you've got.