This is the material and the process I used. Your mileage may vary and if you have done something similar please share. This was one of the most challenging projects that I have attempted in a while. I have attached some pics below of the finished outer roof. While we are a ways from completing this project it is under roof and will allow me to leave it popped up so I can work on it in the evenings. These pics were taken after a week of rain and as you can see I have no signs of leaks.
Back to the roof. I used 2×2’s to frame it up then I covered it with SurePly. SurePly is very dense and is already primed so it was very easy to coat. To weatherproof it I used 2 coats / 1 gallon of FlexSeal and it seems to be doing the trick at the moment. I will keep this post updated so you can see how it holds up over time. I really cannot wait to get it insulated and get the ceiling up. I will also be adding an air conditioner in the very near future.