All the Newmar coachs I have owned had this metal strip around
the perimeter of the fiberglass rap, an rubber roof. After placing corking in seam its screwed thru rubber an 'glass into plywood of roof support.
With all the problems I have seen about the Winni roofs lately sounds like a good start for a "FIX".
Never had a problem with the way Newmar has done their roofs. Expansion and contraction has never created a problem either. Just food for thought for anyone with this problem.
If someone does this I would use stainless screws, thats something Newmar has overlooked, cost I would guess.---"007"