While your sealing or resealing, for cheap insurance, go ahead and put some dicor over those 1000 screw heads down each side where the aluminum roof radius meets the fiberglass roof. The screws are hard to see in the picture, but that's cause I had sealed over them. I mentioned it at the service center up there, and they agreed better safe than sorry. Screws can weep water very easily, and they are not sealed over from the factory, at least on our 2013 3121 it wasn't. I think I added at a minimum 2 full tubes of dicor to that roof to get it where I was satisfied with it, before we ever took it out of the garage the first time.
John and Rebecca Dickson
Emma-7 / Little John-5 / Iva-1
Full Timing Again, Rev B
2013 Ford F-350 Lariat CC LB PSD
2015 SOB TT - With OC's Awning Poles (#8)
At least in Heaven, RVs will be perfect, and I won't have to keep fixing them.