I have used plenty of eternabond. I remove anything that is loose or kinda loose. The rest I leave in place and clean well before application. I think I used mineral spirits or windex. Looks like webseal might be best for the roof all though I used regular. Eternabond is great product just make sure what you apply it to is clean and adhered well to the surface all ready. I also really like dicor lap sealant as well. Same rules apply as far as being clean and good condition before application. Either works great.
