If you are new to buying an RV, you will come across this verbiage and no doubt see the effect it has on the sidewalls of an RV. Many "dealers" are passing badly delaminated RV's off at no reserve. Why? Because they buy them cheap and you simply don't know what to look for. They say things like "clean sides", "look at the shine" etc in their ads. But asking whether it has delamination should be one of your first questions to any seller and have them email that info to you, just in case you need it later. An RV that has it is worth far less than a well taken care of unit. I've also heard people say "de what?" Any RV'er KNOWS what it is!
I'm not going to give a highly technical description about delamination. You can probably "google" it for more information. It is however, the separation of the material in the sidewalls and it's caused by leaks from the roof or windows, but most likely the windows. Many people do not have a shelter for their RV and so the caulking around the windows, vents and air conditioners(anything on the roof) can deteriorate and start a small leak. Once water gets inside the inner wall and the outer wall, it causes a separation which is evident by the waves in the sides of the RV. The sides should be straight. Class C RV's especially leak over the cab(all of them do eventually). So, when you look at a picture, look at the windows and follow it down, if you see waves, that's delam(delamination). It is cosmetic but it also means there was a leak at some point and the wall is weakened. It does result in many RV's being pawned off as "good units" when they are worth far less than the asking price. NADA doesn't figure delamination in the value estimates. Think about buying a house that has a sagging wall, who would want it?