The wall behind our shower recess is badly water damaged. We have been told that water has got into the wall through cracked grouting at the bottom of the shower (it looks OK to me!) We would like to fix the problem and be able to paint the wall. What can you advise?
You should do further testing to verify that this is not a pressure leak on the supply side from the water piping or a pressure leak between the shower valve and the shower head. If neither of these, verify the shower pan is leaking.
If the shower pan is leaking, your only real solution is to remove the tile in the bottom of the shower and up to about 8″ up the walls (remove at least to a height of 4″ above the top of the entry curb) and remove the tile over the curb.
Behind the tile you will find a shower pan. I recommend using an approved pvc shower pan material over using 4 psf lead.
After testing the new shower pan for leaks, new matching tile will need to be installed. Sometimes this becomes the problem, you can’t find matching tile.
I am not giving instructions on how you can replace the shower pan yourself, only so that you will understand the process the plumber will go through.
Call a qualified and licensed plumber and tile setter for this.