Bathroom floor problems

[R1NW00D]

I have looked through all the discussions and just couldn't find the answers i was looking for.

So here it is. Just got a new house and I'm remodelling from top to bottom one room at a time. I want to do as much as i can by my self for the satisfaction and to learn. So I've started the bathroom, ripped everything out and even ordered a new bathroom suite. The problem now is the floor around the toilet has a damp stain that stinks of urine. It hasn't completely ruined the floor, which is chipboard, but i cant seem to scrap it all off.

My question first is can this be treated to stop the smell and put ply on top then tile or should i remove the chipboard and replace with 25mm ply. If i replace completely can i cut along the wall line leaving an inch or so of chipboard around the whole room? Just because I'm not sure if the boards go right under the stud wall or not.

All advice is welcome!

 

[TheVictorian]

Remove as much as you can and replace with ply.

 

[R1NW00D]

Thanks victorian.

Ok can i just check my method real quick? Im gunna cut at close to the wall as possible with a skill saw and pull up th chipboard then just drop 25mm ply in its place as tight to the left over chipboard or wall as i can and fix down. Then adhesive and tiles straight on. If im missing something glaringly obvious please let me kno!

Thanks for your patience