Help with repairing ceiling panel / water damage - 2001 Designer Class C
I just recently found three to four different spots in my ceiling panels that I assume have water damage due to the bubbling and wrinkling of the underlayment cover. After thoroughly resealing my roof, I explored one of them from the interior, confirmed it (still moist) and found the construction to be very different than what I'd researched on ceiling panel repair via youtube. It appears there is a styrofoam sandwich going on in there - underlayment/styrofoam/underlayment - with the top of the sandwich being in contact with the roofing material.
Not sure what my next DIY step is or if there is a next DIY step. Is repairing this something I can do myself with some common construction know-how? Do I scrape out all the styrofoam down to the underlayment in contact with the roof and then fill with traditional insulation? Let it dry out/spray any mold/cover it up with another sheet of underlayment? Are there any joists in the ceiling panels to reconstruct with?
I would love to hear from anyone who has managed this on their own. Extent of work, complexity, materials.....????
Thank you in advance for any guidance!!