Water damaged wood floor

[homesolutions]

Good evening, i have a bathroom to repair the whole bathroom is in a basement and the floor has been built on a wooden joists.
The floor is chipboard and it looks like it now takes on the impression of the joists underneath.
The floor over time has become wet and now because it is so wet that the bath moves slightly so we need to rectify the problem.
I was thinking that wait for floor to dry out then put a new water resistant ply down on top of the floor.
My only problem is that i do not think that the floor will dry out so the other alternative is to rip out the old floor and put in a new one.
Please help with advice on the matter please.
Thanks in advance.

 

[Symptoms]

homes - pull the old up and replace with 18mm exterior grade ply. Joins between ply sheets to meet over joists, other joins support below with screwed-in noggins (crossways bits of 75mm x 50mm). This support is important to prevent flexing at the joins and critical if you then tile (avoids cracked tiles). Screw the ply to the joists. You can get tongue & groove ply if you prefer but plain-edge is OK if supported.

Also, sort out any leaks FIRST.