The shower is sitting on a wood frame and is undamaged. The house is
only 8 years old and the shower base was untouched. The vast majority
of the damage was in the left side of the area I cut out. I cut a
bigger hole because I plan to replace the plywood in front of the
shower (extends a few inched under the front lip of the shower) with
something a bit stronger and seal it real well to keep from having to
do it again. (Of course I'm going to seal the tile in the corner when
I prepare it REAL well and keep a better eye on these kinds of things
from now on) The underside of the fiberglass base is also reinforced
with concrete and metal. It is okay except for the one corner. I can
jump up and down in the shower and it's solid as can be.