My floor was originally done with sheets of plywood run horizontally and then laminated with fiberglass. Luckily, it seems like I'm only gonna have to replace one of the full sheets, and just patch the two other external sections. All of the interior flooring is intact and I don't care to mess with it. You can see in this picture that the flex has been so bad in this center section that it's already torn the fiberglass for me...made finding the seams a snap!