Shower diverter valve was leaking down back of drywall base in a ceramic-tiled tub/shower cove.
Home is 44 years old; replaced the original plastic tile with ceramic 30yrs ago.
Because of the leaking packing the wet 3/8" drywall lost its integrity, and the surface paper adhesive relaxed its grip. Hence-
I think repair = pull the tiles off the damaged drywall section, and carefully remove the grout.
There is some concrete-based wallboard in 3/8" thickness. It's stiffer and stronger than the gypsum-
based stuff, and I intend to reuse the old tiles.
This wallboard is not covered with paper, so, no glue to come loose over time. Whatever you do- make sure the drywall will stay *dry*.
OK, it worked pretty well for 44 years. And, I should have replaced the drywall with concrete wallboard
30 years ago, but- Who Knew? I'm no carpenter, just a laid-off electronic "sparkey."
Rots a' Ruck - ray