These things just aren't intended to last 30-40 years, are they?
If you get every last leak sealed and stopped, there's still all that
condensation running down the insides of the walls and soaking the
plywood floor.
My trailer was used for about 5 years then stored in indoor dry heated
storage for about 20 years. Now that we've been using it for about 8
months we're seeing water damage from condensation, plus the toilet
overflowed and soaked the carpet and pad in the bathroom. It's not inside
right now but I have a dehumidifier in it, running full time at the
driest setting. I plan soon to have a shed built for the trailer, and
keep the dehumidifier going.
Al