I recently purchased a 2000 Georgie Boy Pursuit motorhome. I subsequently discovered water damage in the walls and floor below three windows in the living area. I've removed the damaged OSB flooring (wall to wall) and replaced it with plywood. I removed all the cabinets and one of the windows today to get a better look at the interior construction of the wall. The wall appears to have been a multilayered structure consisting of (from the outside to the inside): a fiberglass shell adhered to 1/8" luan plywood, adhered to 1-1/2" styrofoam insulation, adhered to another 1/8" luan plywood, covered with a vinyl wallpaper. In the areas damaged by water the luan turned to mush except the the thin layer still adhered to the inside to the fiberglass.
As I removed some of the damaged luan and foam, I was surprised to discover there were no studs or supports for the window of any kind except the foam board itself. I subsequently read elsewhere that the factory likely vacuum sealed the exterior fiberglass shell and foam wall board together as a unit before attaching the completed wall assembly to the chassis. Apparently that technique provided enough strength and rigidity to reduce or eliminate the need for studs. (Remind me to not be in a motorhome that flies off a cliff and lands upside down.)
I've read a lot about how to glue plywood/foam to the inside of the fiberglass to minimize delamination bubbles, but I'm not comfortable about installing a foam board patch in a wall that was intended to be a single structural unit. I'm thinking that instead I might establish the outer limits of the patched area with vertical studs from floor to ceiling, and augment those with a framework of studs around each window. My question for those of you who have taken on this or a similar job is this. Does my understanding of how this RV was constructed sound correct, and does my approach sound good, bad, insufficient or overkill?
As I removed some of the damaged luan and foam, I was surprised to discover there were no studs or supports for the window of any kind except the foam board itself. I subsequently read elsewhere that the factory likely vacuum sealed the exterior fiberglass shell and foam wall board together as a unit before attaching the completed wall assembly to the chassis. Apparently that technique provided enough strength and rigidity to reduce or eliminate the need for studs. (Remind me to not be in a motorhome that flies off a cliff and lands upside down.)
I've read a lot about how to glue plywood/foam to the inside of the fiberglass to minimize delamination bubbles, but I'm not comfortable about installing a foam board patch in a wall that was intended to be a single structural unit. I'm thinking that instead I might establish the outer limits of the patched area with vertical studs from floor to ceiling, and augment those with a framework of studs around each window. My question for those of you who have taken on this or a similar job is this. Does my understanding of how this RV was constructed sound correct, and does my approach sound good, bad, insufficient or overkill?