Today's cheaply built trailers are the cause of this. No RV is exempt.

My dad had a trailer (toy hauler) that appears in great shape. One spring we took it out and felt a soft spot in the floor near the door. Took it to a rv repair shop and the whole wall was black and most of the floor. The cost to repair was more than it was worth.
Walked away from it except for the cost of new tires.

Cause---- weak frame which caused the box to flex and leaks started at the roof.
Bottom line;;;; keep em covered (no tarps) in a structure if you want em to survive and Google what you have or are about to get into. You'd be surprised.
Now he has a motorhome under a steel structure he had built next to the house. No worries.
My TD is garaged when not camping.
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