Thanks for your advice. I was not planning to remove the outside skin... just do the best I can to makeup for not replacing the luan. I noticed the bedroom wall had been replaced prior to me owning the coach and I saw some sort of spray insulation when I removed the electrical outlet to inspect. Appears it was professionally done so I was curious if this was a common repair procedure. That wall is also on the curb side of the coach so I suspect that area was leaking at some point from the seam along the roof similar to the area I’m dealing with now. Hopefully you can get back on your project soon.

If you have already begun dismantling the wall from the inside, your job, like mine, is twice as big, as there is no practical method for repairing the exterior luan from the inside. For small spot repairs, I think you could use vacuum bonding or, where possible, mechanical clamping, to adhere a fresh reinforcing layer of luan to the affected area from the inside. I have no doubt, at this point, that it is less expensive in dollars, and especially time, to simply purchase another motorhome that is in better condition. In the current market, even sending mine to a salvage yard for zero dollars would cost less than repairing. If you have a strong desire for a custom interior, that is a good argument for extensive renovation. For an as-built configuration, I would start from scratch with a well-maintained, clean motorhome.

For protection from catastrophic rodent damage, I would use attach metal screening in each of the vertical and horizontal wall framing members to block access through the huge round holes, and some kind of sealant to fill the gaps where the wiring passes through the aluminum members.

Reply in three parts due to message length limit.

Due to the COVID-19 pandemic, my project is at a standstill.

However non-intuitive this may seem, I am convinced that the best way to deal with damage to the luan substrate in the exterior walls is to remove them from the outside. If I had to start over, I would simply remove and replace as much of the outer skin as is necessary to make repairs. I think that, from a standpoint of preserving future ability to perform modifications and repairs, I would use batt insulation instead of spray foam insulation. I think that, in addition to complicating future work, that the spray foam will not work favorably with water vapor and condensation inside the walls. I think that rock wool may have some advantages over fiberglass, especially for the inevitable rodent intrusions.

Hello, I was very much interested in your renovation as I have had similar issues with my coach ...water not mice fortunately. I do have the very same water damage to the luan type wood on the curbside interior wall behind the right front seat. Yours is in better shape actually as most of my wood has disintegrated. I was curious how you repaired. Easy to replace the paneling and insulation board by cutting out new walls but I wasn’t sure what to do in between the wall joists as this “luan” was originally glued to the outside skin. Originally it had regularly fiberglass home insulation but Ive seen were some have used spray foam insulation. Any suggestions? Thanks again for sharing the photos!!