One of the issues I discovered upon getting my new Sunline fifth wheel home was that on the driver's side, something had punctured the black woven vapor barrier on the inside of the wheel well. Maybe a stone or something larger.
Then of course the rain and water got in, and I ended up removing a significant portion (about 12 feet in length) in order to get out the wet insulation before making the repair. This is a horrible design IMO, as this material is not very durable when confronted with all the strange things that tires can kick up. Incidentally, on the other side of the coach there is sheet metal protecting the inside of the wheel well. This gave me the idea to do something similar.
Here's a pic of what it looked like after the vapor barrier and insulation was removed, but before the repair:
The affected area was about 12 feet long, and there was maybe 3-4 inches both on the vertical surface (bond or lentil) and another 3-4 inches on the horizontal surface (bottom of joists, and ending at the I-beam).
So I went to Lowes (cause it was Saturday after all) and bought some aluminum roof flashing (10" wide roll, 50' long, about $20.). Then I bought some self-tapping screws with rubber grommets (this is to screw up into the top rail of the i-beam, from underneath). The top was secured using galvanized screws (countersunk) through 1" aluminum strip, through the flashing, then through a strip of butyl tape into the bond. This design should be impervious to water, but I caulked behind the flashing and above just to make sure.
One thing I did not account for is that the i-beams do flex a bit during travel so sometimes the flashing crinkles a bit, but after a 500 mile trip this weekend everything is still completely secure and dry.
I'm a little concerned that some water remains in the underbelly in the middle of the trailer... not a lot but there are some wet areas of insulation. Just the bottom 1/2" of insulation is damp, but it's not possible to get all the water out without cutting entire underside open, which I would really like to avoid for obvious reasons.
I'm wondering if there was a better repair for this, or if anyone has encountered this issue before. The unprotected wheel well seems to be a horrible design that certainly must have affected people other than just me.