I had similar issues with our 2005 31C, and did all the work myself... spent around $200 in material but only because the filon exterior was still intact. I’m not suggesting anyone else try this if they’re not comfortable destroying walls or taking apart your rig... way too many opportunities for things to go bad.
For the floor, I had to first take apart the bunk area from the inside, remove all the exterior corner trim, and then carefully peeled back the fiberglass cap from the bottom. That created an opening we could slide full 4x8 sheets thru to lay down for the cabover floor. I could have used pieces cut to come thru the door, but I didn’t want to lose any strength. I also left in place the original 1” marine plywood —it was spongy at the edges, but the center was still solid. The new plywood got anchored to the original by putting in screws every six inches left to right and front to back.
Hardest part was the wall over the drivers door. It was fully delaminated, and I had to build a new foam core wall around the aluminum framing. I knew it wouldn’t ever be as strong as the factory vacuum bonded sandwich wall, so I made up for it with thicker wood and thinner pink closed cell foam. The interior wall was then attached to the metal frame with self-tapping lathe screws.
So far, it’s holding up, but I will probably redo some of it when I reskin the front cap and remove the front window, and may remove the side windows as well. That’s a job for a barn or large garage bay (and I have neither) so I’ll save that for another off season.
- 2019 Grand Design 29TBS (had a Winnebago and 3x Jayco owner)
- 2016 F-150 3.5L MaxTow (had Ram 2500 CTD, Dodge Durango)
- 130W solar and 2005 Honda EU2000i twins that just won't quit