notice you say your going to re-seal the roof. I get tired of climbing up on mine every yr or so to re-caulk, going hi-tec and permanently this yr
Alsans RS
use this at work, it is incredible stuff, lightweight, practically indestructable once hardened, and will last over 50 yrs. It's not cheap, the can pictured is around $300, but they come in smaller gallon sizes. It's a 2 stage that has to be mixed, and you most certainly want to be wearing gloves and old clothes.....it will take weeks to get off your skin...ask me how i know...
and if your roof is any kind of metal (mine's alum) you will also need this primer
all in about $100-150 to do, more than caulking, but that's far outweighed by the fact you will never worry about it again-ever. piece of mind....