Water leaked from the upstairs shower through a light fixture in the kitchen below. The shower floor is 2 x 2 tile and drains into a foot bath. The leak was between the tile and a marble border between the foot bath and the shower floor tiles. I was going to reseal, but decided to remove the marble to get a better look at the floor beneath. The floor appears to be 2 x 2 tiles about 3/16 thick, then cement board (or mud job since it is 1 thick?) then ¾ plywood, then ½ (rubber or foam or insulation?). The plywood is rotted. I have left it open and the rotted drywood appears dry, but I can only see the edge. I had a local flooring company visit to give an estimate, and he suggested that I just replace the marble since the flooring is solid and replacing the plywood could turn into a big job. He thinks that allowing the plywood to dry out and sealing correctly would be safe. The house is 12 years old. Does this sound like a valid solution? Thanks!