Dante M. Catoni wrote:
My bathroom floor is constructed as follows from the bottom up
2" X 8" joists 16" on center
3/4" X 7" boards running perpendicular to joists
1/2" x 7" boards running parallel to joists (very wavy)
3/16" plywood?
ceramic tile

Where did the cracking start? Around commode? Something is rotted?
What do you mean by "wavy" - the edges aren't cut straight or they are
buckled/warped?