I really do think that at least half the fun is keeping her looking as new as she does.
After returning to Florida from a recent trip to New Jersey, I noticed the floor near the front, right hand corner of my 1987 Avion, 30P model showed signs of wood rot. I have attempted to outline the procedure, complete with photographs, I used to repair the damage and locate the leak(s).
Before you begin, buy a good square drive screwdriver. Almost every screw you will remove will have a square head (Robertson Head). You will need a power saw, chisel set, notched trowel, hammer, mallet, utility knife, metal square, or straight edge, shop vacuum, router with a 1/4" x 3/8" square bit, electric drill, and rotary wire brush, belt sander, mineral sprits, plenty of rags and a container to store the screws. The first problem was removing the sofa/bed. Removing the lower portion of the sofa/bed from the brackets gave access to the screws that hold the sofa/bed to the floor. You will need someone to hold the lower section of the sofa/bed while you remove the screws that secure it to the frame. You will have to lay on your back to access the screws. I found that I could move the sofa bed to the left side of the trailer which gave me more then enough room to access the floor area that was damaged.
I outlined the damaged area using a steel straight edge and pencil making sure to include all the rotted plywood. Then I proceeded to cut out the rotted wood section. It was a messy job. Removing the rotted wood required the use of a rotary saw, wood chisels and a rotary wire brush attached to a drill motor to remove the rotted wood from under the wall. It looked much better after I vacuumed and cleaned the area. Classic Avion trailers have a 6" wide piece of aluminum that runs along the bottom of the interior wall. Removing this piece of aluminum by drilling out the pop rivets will allow a better view of the damage under the wall.
The Avion floor is fabricated in three layers. The bottom layer appears to be 3/4" thick plywood. The center section is Styrofoam and the top section is 1/2" plywood. I removed a portion of the Styrofoam to inspect the bottom layer of plywood. Fortunately, it was not damaged. I replaced the Styrofoam using adhesive designed for Styrofoam. You can find this adhesive in a caulking gun size tube at Home Depot or Lowe's Hardware.
Next, I used a router to cut a 3/8" wide by 1/4" deep square slot (half the thickness of the plywood) around the perimeter of the opening. Doing this provides a "step" so the new plywood will have support.
Use a piece of cardboard to model the size and shape of the replacement plywood. Take your time here and make the template as accurate as you can. Make sure the template fits into the 3/8" x 1/4" step that was cut into the existing plywood.
Most lumber supply houses no longer handle 1/2" thick plywood. In the interest of conserving a few trees, the so called 1/2" thick plywood now measures 15/32". A piece of tar paper placed between the Styrofoam and the bottom of the new piece of plywood will make up the difference. It was probably overkill but I used exterior plywood for the replacement floor.
After cutting the new piece of plywood, make sure it fits the opening exactly. If your template was accurate, it should fit. If not, you may have to trim it so it fits perfectly into the groove that was routed into the existing plywood. When the new piece of plywood fits exactly, cut a 3/8" x 1/4" groove in the new piece of plywood to match the groove that you cut in the plywood floor. Be careful here. Make sure you cut the groove on the side that will match the groove cut in the existing floor. Check again to make sure the plywood fits the opening.
Using a notched trowel to spread adhesive that is designed to be used on Styrofoam, I laid the tar paper on top of the Styrofoam. Then I spread adhesive on top of the tar paper. I also spread adhesive in the groove around the perimeter of the opening and placed the new piece of plywood in the opening. Press the new plywood firmly in place. Make sure it fits the opening and the edge is laying flat against the existing plywood. I used my slightly overweight body and a plastic mallet to assure the new piece of plywood was firmly in place. Using a rag, wet with mineral spirits, I cleaned the area where the adhesive oosed out from the joined pieces of plywood.
After the adhesive dried overnight, I lightly sanded the area with a belt sander, vacuumed and cleaned the entire area and applied vinyl adhesive using a notched towel. Then I replaced the original vinyl. I use a wallpaper roller to smooth the vinyl and make sure the vinyl was held securely in place. Depending on what type of adhesive you use, clean any excess adhesive with a rag soaked in mineral sprit's or water. Except for the stain that the rotted wood caused to the vinyl, I could not tell that the vinyl had been removed.
Replacing the sofa/bed proved to be more of a challenge then removing it. Finding the existing screw holes tried my patience but with the help of my lovely wife, we were eventually able to find the existing screw holes and fastened the sofa/bed securely to the floor. Some parts of the sofa/bed are screwed directly to the wall or to pieces of 1"x1"x3" wood that are screwed to the trailer wall and floor. Replacing the lower section of the sofa/bed completed the project. It was a messy job but after it was finished I felt it was not all that complicated. Just take it one step at a time. --- Bill Rahm