edh- Thanks again for your response and advice! Decided to use Eternabond tape on all seals, and will then roll Grizzley Grip over it all. I basically finished the roof sandwich. I am now waiting for adhesive to cure before I finish primer/paint on the ceiling. Then I'll be able to flip the roof and repair the hail damage and waterproof it. There is only one significant change I made to my Roof Sandwich rebuild. I added the correction in red below... "Roof Sandwich I will reuse the aluminum roof skin. Plan to semi flatten/pound the worst of the dents, Gold bondo the rest. I'll use LocTite PL Premium to re-adhere the roof skin within the existing aluminum frame. I'll use 3/4 " R-Tech or Foamular insulation (whatever they have in stock) for the next layer. I'll be adding four cross-roof braces, using 1"x3" wood glued to the aluminum roof skin also using LocTite PL Premium. These braces will notch into the roof frame and not only provide additional support, but also will help keep all layers tight within the roof frame. I'll cut foam to fit around the new wood framing/supports. I will place wood supports where the screen door hardware should be on the ceiling. Not sure if I'll ever use the ceiling to store the screen door, need to source the parts and figure out how that all works first. Figure I'd prepare for it and add a couple more supports to the other end of the roof too. Total roof weight will only be slightly heavier then the original with additional braces and bed liner. Plan to use FRP panels for the ceiling. Think I'll use Titebond FastGrab mastic to adhere FRP panels to the foam. I plan to add electrical for one or two lights as well. Instead, I used 5mm (about 3/16") Revolution Plywood. Thinner than 1/4" plywood, thicker than the original 1/8" paneling, but I was still able to squeeze it into the original roof frame. I used Loctite PL Premium for this step as well." Soooo, originally I planned to use FRP panels for the finished ceiling. Figured it would be water/rot/mildew resistant, and also a clean wipeable white finish I wouldn't have to paint or maintain much. However, after some research here on PUP and elsewhere, I determined FRP may not be the best choice for my project. I then went to the local box stores and picked up a thin, white plastic sheet material. Figured it would be light and hoped it would adhere better to the ceiling. What I thought of using... What I ended up using... The Revolution Ply worked real well. Still light, but will provide needed structure/rigidity.