Well it is true, removing the floor is a B-I-O-T-C-H. The plywood floor is bolted to the frame along the sides through the bottom wall support and along the center supports. Most of these bolts have rotted at the top and in the middle. Most of these had to be cut off or grinded off. Sparks were flying and setting the trailer on fire was a possibility. Getting the bolts out of the wall supports was a major pain, the grinder was hard to get into the spaced needed. My Dad claims that every bolt around the wall supports took at least one hour to get out.
In addition to being bolted down, the plywood had plywood supports under the floor at the seams, these plywood supports are glued together and are still holding strong. We used a saw to cut through the boards and take them out in as large pieces as possible. The entire floor was saved so that we would have templates for the new floor going back in. There were also two 18ft 2×4 supports that ran the length of the trailer and were bolted down to the frame that also had to be cut out.
The insulation was removed and I vacuumed the belly pan as much as possible. Moving around in the trailer without a floor is not easy. I would hate to make a hole in the belly pan that would need to be patched. This is a lot like moving around in an attic without flooring
Part of the frame was rusted and pitted in places where the floors were bad. We decided to paint the frame with POR15 (www.por15.com). POR15 can be painted right over rust and is supposed to cover up rust and prevent it from spreading; it will also strengthen the underlying metal and seal holes by forming its own membrane. I cleaned the frame with a wire brush to remove all of the lose pieces and began painting. Moving around and balancing on a small piece of plywood painting while trying to not touch any wet paint was challenging but I’m sure it was well worth it. The frame look much better, even though it will never been seen by anyone. After the frame was dry, I cleaned the actual belly pan as much as possible. It was covered in sawdust, insulation dust and was just nasty. I could not get it perfect, but it is much cleaner that it was.