Chinook RV

I just acquired a 77' Chinook that had been used as a storage shed. Once I got all the car parts, tires (none of which belonged to the van) and other junk out there wasn't much salvageable. I'm pretty much left with a fiberglass shell with a shower, toilet and water heater.

Does anyone have an idea of how thick the wooden subfloor is? The rot only goes a half an inch deep, all it took was a floor scraper to take it off and I'm wondering if or how I can treat the remaining floor so it won't continue to rot and last longer.

I was thinking about sealing what is left of the subfloor with a fiberglass shell, wall to wall whit ribs so I could insulate between before I put down a new floor.

I've worked on cars but not a vehicle with a wooden subfloor?

I know nothing about the '77 Chinooks. If yours is based on the Toyota, then this link could be of help.
FWIW: always helpful to include some basic model info when reaching out for advice on the forum.

http://aricbeaver.com/2017/09/toyota-ch ... is-restore

He said van, so I think its a regular Class C Chinook, probably a 18 Plus, not the Toyota, since it won't have shower.

I have no idea about how the fiber glass shell is attached, but maybe it is worthwhile to check to see if it can be lifted up and have the subfloor replaced? I know that there are a few attachment points that bolts onto the frame, and there is some kind of rubber under the subfloor used as a cushion/absorber. I do see some empty Chinook shell that people used as a shed, without the chassis, but that's on computer, never with my own eyes.

Hey lil'Static, here's just one of many interesting sites for things to consider when doing a DIY van build. Good tips, how to's and references.
https://gnomadhome.com/build-your-van/

chin_k's point about lifting the shell to do a complete floor replacement would be the approach I would consider. Always best to start with a "new foundation" sort of thing. This would also offer up the opportunity to do any repair/upgrades to the chassis frame/components. If not that, and depending on the condition of the base, scraping off the rotted top layer of ply and fitting new would also work. The original base layer could be sealed with a number of available products to prevent future rot.
Best of luck, and keep us up to date on your project!