It is hard to visualize all of what you are saying but in general I believe it is agreed among those who have done testing that liquid Silicone topping is the longest lasting and the most flexible most UV resistant of all the different liquid options such as acrylic or EDPM etc.? One popular brand is "HENRY".? ?There are? a few others.? ?However, nothing else will adhere to it when cured except silicone.? ?Sometimes it is a good idea to embed fiberglass tape into a wet coating and then apply another top coat within 24 hrs.
Caulk is sometimes necessary and again silicone is best and again sometimes if there is movement in a joint or seam due to mechanical movement or hot cold fluctuations a fiberglass cloth or tape should be embedded.? ? ? When using? adhesive tape for sealing,? Eternabond I think is regarded as the best and longest lasting.? See the many youtube tests of RV roof repair at Youtube.? ? I dont know what the Eternabond compound is but I think it is Butyl Adhesive. and can be top coated with silicone? coatings like Henry.? ?Lastly, the Silicone coatings are double ( or more ) of the cost of other RV roof coatings..... but if it lasts 2 or 3 times as long,? is cost justified.? ?There are at least several dozen RV roof repair videos at YouTube? ? One that surprised? me was "Gorilla" white roof patch and seal tape.
