The original particleboard floor of our 1995 Chalet camping trailer is rotten and had to be replaced. I knew this when I bought it. After removing all the trim and obvious fasteners, the next step was to pry the camper shell from the floor. Using pry bars, leverage and blocks I was able to lift the shell from the floor enough to add 2x4's to create a beam in which to jack the trailer up off the floor. The trailer was stripped down to its cabinet framing and then braced to keep the side walls from spreading. I used a 2 ton floor jack to lift the trailer shell and then set it on jack stands so the trailer could roll out. I had to cut off the top of the tongue jack (rusted out and will be replaced) in order to clear the camper shell that was sitting on the beams. I replaced the rotten wood beams on both the front and back of the trailer where they had been sitting on the rotten floor. The new floor is comprised of 2 layers of 3/8" plywood glued together to form one 3/4" sheet. The bottom of the new floor is treated with a bituthane stick down membrane that will provide water proofing. The top of the new floor has new vinyl that was installed prior to putting the camper shell back on. The process went surprisingly well and I could roll the trailer back under the camper shell at night to keep it secure in the garage.