Need a waterproof method to permanently cement a 15" x 20" x 3/8"
rectangle of polypropylene board (same compound as a regular kitchen
cutting board) flat against a tile shower wall.
It's to protect the wall from continuuing damage and cracking of the
ceramic tile from the angle support for a handicapped person's folding
shower seat. It was attached to the tile by lag bolts into 16" center
studs at seat level and has the folding wall support under the seat
that folds out against the wall that's doing the tile cracking and