A: A leak that rots an RV floor can come from the roof, a side window or equipment access hatch, a damaged or badly-installed underbelly material or leaky plumbing, Frank, among other sources. It’s not a surprise that it’s going to cost that much for repairs. Getting that deeply into an RV’s floor structure requires a considerable amount of disassembly and removal of interior furniture, cabinets and the like, plus replacement of any nearby framing that’s also rotting. It’s a big job that needs to be done by a professional with that kind of experience if it’s to be done right.
In addition to repairing the damage you’ll need to find the source of the leak so it doesn’t happen again. Have you been checking and repairing your roof component sealants on a regular basis, like twice a year, at least? It’s a good idea to get up there and clean and inspect the state of the sealants around roof vents, the air conditioner housing, various pipe vents and so on. It doesn’t take long to repair these spots with some of the sealant recommended for RV rooftop use. Also check the roof for damage such as rips or other impact damage that can cause significant leaks. The same applies to sealants around windows and sidewall access panels. You can find where these sealants can need some repair, and check the wall or compartment floor for stains or other water-related evidence. Of course, it’s also easy to spot any plumbing leaks inside the cabinets, and those repairs are fairly straightforward. Good luck with the project! – JJ