“ The dealer he bought it from ( a couple of years ago) had just added new OSB and linoleum over parts of the rotted original floor. “ Therein lies the problem

.... the dealers use the same Crap materials to fix the trailers so it rots again just as fast ...

Also they use that same caulk that doesn’t seem to last very long despite all the wild claims ...
I’d go back with the best grade of flooring OSB and use the mix which we KNOW works .... and then store the whole thing INSIDE ...
It was all this RV trailer business that led us to Foamies in the first place ... Classic trailers from yesteryear are no longer so well made ... and new trailers are lucky to survive the warranty period ... I’m not making this up , if you read the RV forums you find two types of RVers... Those that constantly inspect and chase down problems before they develop( high maintenance) and those that pay a LOT of Money to RV dealers annually for much necessary Maintenance ... Myself being OLD , I’d rather something
that’s actually made to live outside , like a car, truck , house , or Foamie trailer ...
Note: When I pinned down our RV dealer about the roof sealant , he said I should inspect the whole roof , once a month , and have the caulk
replaced , once a year by him ( at an annual cost of $1200.00 USD...

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