This year bus has sections of ridgid foam insulation in between the frame work. The foam was sticking out proud of the metal by 1/2 inch. It had to be built that way. Crazy. When you rivet the skin to the metal, at top and bottom, the foam pushes out the middle causing this slightly bloated look.
Chances are that the skin was installed first, and then expanding foam injected between the outer skin and inner panels (assuming there are inner panels). The expansion force of the foam is considerable, and will easily distort sheet metalJeremy
Nope. This foam is cut to fit foam. Individual pieces inside the frame openings. Nice smooth beveled edges. Loose from the framing. I sprayed in the foam on my 82 and this stuff is different. It's thicker than the frame material and therefore stands the skin off a bit. Maybe the skin on the inside has bowed in and is pushing out the foam, but I seriously doubt it (having removed inner skins before.) These inserts just look too thick for the job.