Well documented piece, ZEP! BTW, the new units are screwed into the roof and inner skin (I just replaced a Fantastic fan and dead vent with two Maxx Air fans) and I hope that you are using 'butyl tape' instead of 'putty tape' on those vents.
I know it might be a little late, but the butyl gives a better seal and won't eventually harden like the putty tape will......and just a buck or two more per roll. I actually don't use either, but use a self-leveling roofing sealant from Dicor for sealing the under sides of the fans and applying it LIBERALLY around the top, over the screws, and again over the seams. It just sort of melts down into a nice smooth blob
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