Bathroom floor rotten in places - Replace with Ply ?

[andytc]

Hi

I'm info gathering for the weekend rip out in my bathroom ...deep joy.

Anyways , the floor was previously tiled onto thin ply laid onto the old boards.
After stripping this out i notice quite a few areas that are rotten to the core ! ...behind the bog , near the bath from water dripping over the top etc , etc. you can poke your finger through the boards ... ROTTEN

Would it be better to strip all the boards out and just replace with thick ply , i've seen 18mm and 25mm WBP (whatever that is) mentioned. the bathroom is really quite small , about 8ft x 9ft , most of the floor area will be covered with new bath , bog , sink area etc.

Also , i don't want a height issue with the hallway ?

Any advice for good lasting job

 

[gcol]

Ideally rip out and replace with 25mm WBP (Water and Boil Proof) ply (exterior grade basically). Ensure you stagger joints so that you don't get 4 corners meeting at the same point and fix noggins (extra supports between joists) where the edges of the sheets will be unsupported. Screw every 300mm to joists.
Have a look at the tiling sticky for general info.