theoldwizard1 wrote:(...)
If other means were used to prevent the walls from racking, could the rolled non-organic material (Filon) be applied directly to the studs and rigid foam or woul the "print though" ?
If you get the frame materials perfectly flush, it would look fine.
But if there's any variation in thickness, time and heat cycles may eventually lead to what the steel boat world calls the "skinny cow" look.
All 'Filon'-skinned (and several aluminum-skinned) RVs or trailers that I've dug into far enough to see a wall cross section or full construction details have had something between the skin and the structure.
A few samples that come to mind:
For a time, Winnebago was using ~0.020" sheet steel between the steel frame (and foam core) and the fiberglass skin. The steel sheets were bonded with a good adhesive - no fasteners, whatsoever. Some 'waves' could be seen on the outside, but the overall appearance was pretty good.
Pretty much everything else that I've been into has had a laminated sheet of peeled and dehydrated tree carcass (a.k.a.: plywood).
...With one exception: I dismantled an '86 Winnebago that, in most areas, had a single wood ply - basically a ~3/64" veneer - between the continuous sheet fiberglass skin and the frame. The walls seemed to have been assembled while horizontal, from the outside in - skin, 'veneer', frame and foam, then wired and packed/padded where necessary, before treatments were added for the interior (various types of bracing, sheeting, etc. are used for wall/cabinet attachment points, table mounting, dent/puncture resistance around dinettes, heat protection, appliance mounting, etc.); and finally the interior skin (generally glued to the frame only).
The racking strength in all of the above came from the frame. The skins were doing much, if anything.
Personally, I wouldn't count on adhesive between dissimilar materials for racking strength. Sheet, glue, and screw!
