[JRTJH]

You "should see", starting at the top, a thin, vinyl floor covering, a 1/4" OSB (or two 1/8" luan ply sheets), 1.5" white rigid foam sandwiched between the aluminum floor stringers which are 2x2 or 2x3 square tubing, and an underlayer of 1/8" luan. The entire assembly is "wrapped" in DARCO, which is a "black plasticized, nylon reinforced, waterproof fabric" (think blue poly-tarp). All of this is laid on top of the steel frame rails and fastened to the outriggers along the extreme side edges of the floor. The inside walls are then placed in location, the shower and large floor standing cabinets are installed, then the outside walls are placed in position and secured to the outriggers with bolts through the floor.

Taking the trailer floor apart will be "impossible" if you try to do it in one piece because the walls are fastened above the floor. You'll need to carefully identify the location of the floor stringers, then remove the flooring in layers, being careful not to damage the underlying structures. You'll need to work around the "rigid heat ducting", the floor stringers and any electric runs that might be embedded inside the floor. Typically the electric/plumbing runs are under the floor or above the floor (inside cabinets) but as sure as you "decide they're not embedded in the foam is the one time you cut through something important and not repairable.... So, be careful.

There are a few threads in the past couple of months with photos of repairs people have done to their sandwiched flooring. Looking at those photos will give you some ideas on what you "might" find.... MIGHT is not always what you'll see in your specific trailer......