I have a leak in a pipe behind my shower and yet I have PVC paneling on the wall so don't want the plumber to have to rip out the whole shower. There's an access panel at the side but the pipe is very difficult to reach from there due to other pipes in the way. Can he cut a hole from inside the shower below the taps and then just cover with a large access panel? Are they waterproof enough for shower walls?
If access cannot be made from the other side of the wall, then yes, a hole can be cut in the shower wall below the taps or where ever the plumber deems necessary. I wouldn't go with making an access panel there but would go with a more permanent repair to ensure no leaking. The cutout could be carefully cut. A few supports glued to the back of the wall and then the cutout piece sealed and caulked back in place. A few pieces of tile trim from your home store could hide the seam and could be duplicated on the other walls for uniformity.
Plumbers are used to working in cramped,tight places so they might be able to fix this utilizing the existing access panel.