Some of the side walls are 4 foot sections bonded together with fiberglass. On the inside you can see the seam, but on the outside they sand the seam smooth. That is why you can see vertical lines where the gloss is sanded every 4 feet. Not sure why some panels are all glossy, and some have these sanded seams. I am guessing that if you have full body paint that will all get covered up with paint, and if you are getting decals, all the outside has to be glossy. On our 38RLS only the kitchen slide outside wall had the seams, and we are getting full body paint. A few pics of how the underbelly attaches to frame. There is a 1/2 bath conversion to laundry room. Also thought it was neat to see how they attach the bottom trim piece. They obviously cut out all the openings after attaching the trim-lower fender. There were a couple of RVs outside that appeared to be done.