Are you looking at motorhomes or trailers? There are a couple of ways for making walls. A laminated wall is put together with glue, pressurized to seal and forms part of the structural integrity. If water gets into these you get delamination of the walls and lose a lot of the value of the RV. A hung wall is not laminated and not subject to delamination. I don't recall seeing new models with the corrugated aluminum lately. They use a butyl tape to seal these around windows and doors. All RVS have to be checked regularly to keep everything tight and leak free. The constant bouncing loosens any RV.