Lfoxmont, I believe you will find that your original
Burro floor is a sandwich of fiberglass over plywood over fiberglass. Unfortunately, the edges were not always sealed all that well and if water
leaks around the
windows, the plywood gets soaked and eventually delaminates, causing the fiberglass to heave and eventually allowing the floor to rot out. Make sure those window seals are working properly!
Froggie