First time buyers of motorhomes or campers in general, are generally not aware of this potential issue until it is too late. Or of its devastating effects on the structural integrity of the coach, not to speak of your wallet. Yet there are thousands of units sitting in dealer lots and individual yards with this serious defect. A defect that can cost more to repair than the unit is worth. Another writer here, has said, “Water is the #1 killer of RV's.” I agree. Most problems start on the roof or where the roof meets the side walls. But with modern designs that use sliding windows, leaking can occur around them as well. Before you buy ANY of these units more than five years old, you will want to either personally inspect or get a written guarantee from the seller that no rot or delamination exists. By “buy” I mean before you even bid or part with one thin dime of your money. Deposit or otherwise. What to look for: Previous leaks which may have been patched but have already caused damage. Interior ceiling or sidewall buckling, discoloration, etc. Read the following guide for important tips: “Buying an RV. Watch out for water damage!!” I am going to focus on sidewall delamination in this article. Most modern RV coaches come out of the factory with strong, bonded walls, which are a sandwich of thin plastic with thin luan plywood over strips of 2x2 framing and Styrofoam insulation. You could drive a truck over this wall or subject it to 80mph hurricane strength winds without damage. That is, until the integrity of the wall fails. Occasionally this failure is due to poor initial construction/bonding. You may find some dimpling, blistering, bubbles or cracks in exterior plastic that has never had a leak. In this case, it may be no more than a cosmetic issue. But usually, if you see these exterior signs of delamination, water and resultant rot is the culprit. What happens? The sandwich is coming apart inside. Water has gotten down into the walls and rotted the plywood. It is separating and may in fact be totally rotted out with few outward signs. The framework may still be strong, but the wall is weak. Except for a ripple or bubble, the outside plastic skin appears to be okay. But there is no longer strength or integrity to the wall. Expensive and/or time consuming repairs will have to be made. If you whack the wall with a rubber mallet or even your hand, you can tell where the wall is solid and where it has already failed. (This mallet test, by the way, is accepted practice for testing cored boat hulls for delam, so any seller afraid of it, is afraid of the results it will show.) You really don’t have to hit it that hard to find where it is soft and where it is still solid. Often you can spot the delaminated areas by eye, but they may not show up in pictures. Recently, I saw an auction where the seller casually tossed the word “de-lam” into his standard disclaimer statement and I knew it was time to write this guide. There is nothing casual about correcting this deficiency. Indeed, I’d rather buy a motorhome with a bad engine or transmission than one needing sidewalls stripped and rebuilt. If you’ve ever done this job, so would you. Over a ten year period I’ve bought and sold many “big ticket” items on ebay. It is a wonderful market place. But there is opportunity for fraud and deception by the unscrupulous. So, don’t bid blind, at least get written assurances beforehand. Good Luck & Good Ebaying.