Bathroom floor what's best to use?

[richardrich79]

I'm in the process of converting the small front bedroom into a bathroom.
I know the 'normal' course of action is to screw 18mm WPB ply to the existing floorboards but I am thinking to remove the existing floor as some of the boards are not in a good state making levels hard to attain.
Assuming I do this what's best to go down, definitely no chipboard

 

[zed750]

Just renewed my own bathroom floor. Ripped the old T&G floor boards up and replaced with 18mm WBP ply straight over the joists (16" centres) with noggins to catch all edges. Overboarded with 6mm marmox boards, electric UFH, covered the 3mm cables with a flexible SLC and then tiled.

From the pro tilers I've spoken to, minimum is 18mm ply if that's your base. I went for 18mm to keep my final step into the landing as low as possible but you can get thicker stuff. It depends on how high you want your finished floor to be.