After trucks leave the framing & skinning shop they are moved to rough interior shop where every inch of the conversion is insulated. They then add 3/4" plywood to the floor & 1/2" plywood to all the interior walls & roof. Wiring and all the interior walls are added as well. Real studs are used on those interior walls not flimsey 1x2's like most rv manufacturers use. (That is my truck to the right)