Delamination is due to a leak, period! Leaks are typically small but can cause big damage to the RV. If the leak has caused de lamination it may also have caused rotting on the roof and/or on the side where de lamination is occurring. A new roof, done by a reputable RV dealer, will set you back anywhere between 7-10K. I know because I purchased an RV with de lamination and the experience made me scrutinize my rig. To the point that I pressurized my RV and then sprayed soapy solution to all the seams to detect bubbles. Bubbles, when pressurized, meant leaks. And, yes, I found three more.
Luckily, ( if you call this luck) I was in a bad storm a year after the purchase where a large branch fell and penetrated my roof. My insurance paid for the new roof ($10,000). I was a happy camper!
Bottom line is, delamination, according to the dealer that repaired my RV, is difficult to repair. It will never look the same as when new. Be very careful. Know what you are doing or looking for.
My advise: it all depends on the damage the leak has caused, but be very careful with your purchase. It can cost you a lot of money to repair! Unless you're lucky and a branch falls on your rig.
