Def Exposed to the Sun. I'm no roofer and I just short of googling, but doesn't urethane like product exist for area's as such (vent pipes, metal-roof membrane like my roof hatch, etc. AKA, good 2 part urethanes for concrete-sealing has been a game changer for me - Vulkem, Sonneborn, etc. Takes the stretch and doesn't crack, etc. Granted, what in the roofing world exists that plays well with metal-asphalt the best. Currently has regular 19 on it. Whole it's still soft, should I scrape it off and put 19 Ultra ???
Roofer put a coat of 169 after he finished our 3 layers roof - (2 layers of smooth 160, and then tri-ply rubber as the base). I just finished putting a coat of 298 on the wall where where HVAC is going back on, as once it's installed, I will never be able to reach behind this area ever.
Once the HVAC shop is done, and the systems is confirmed working fine, I plan to use up the remainder of the 298 on the rest of the roof.