shower over painted walls

[ryanbrown]

I have another painted wall to contend with.
This time painted platerboard walls around a bath, but there is a shower going over it.
Can I get away with scouring and criss crossing the entire painted area to be tiled on? or is there any other preparation needed to protect the walls from getting damp? Should I prime it? Does the painted need tocome off totally?
cheers again

 

[GazTech]

try some white star on the surface and leave overnight,you have to know if the adhesive is going to react to with the paint....if it does you must remove it all....Gaz