Originally Posted by bisuddha
I would greatly appreciate if you share your expertise with me for the following questions:
1. Do I have to remove all caulks including traces of old one?
2. Do I have to use a primer before application of new caulk ? If so what is the name?
3. What will be the best cleaner to clean the surfaces including remnant of old caulks?
4. What is the best caulking material for use on Aluminum one side of the shim and wood cover with plastic sheet (not sure) on the other side (main roof)?
1. Try and remove as much as practical without damaging the roofing material. A heat gun will help to soften the old caulk and make it easier to scrape off. Be careful using chemicals or strong cleaners to get that last bit of sealant as you could damage roofing material.
2. The need for a primer will be dependent of the product you will be using to reseal the roof. I haven't experienced the need for a primer as yet.
3. The best cleaners will depend on the surface material and the type of sealant you are trying to remove. Acetone will pretty much loosen and dissolve most sealants but could also damage the paint, plastics and synthetic rubber roofs. Mineral spirts are less aggressive but again what might be best will depend on the base material. Soap and water is always best but the results might not be what you are looking for.
4. What to use to reseal? Do you want to do this all over again in couple of years? That's where you will be with the stuff that starts with D and ends with icor. It's not if it will fail and leak but when. 10 years ago I removed every trace of caulk and sealed reseal 95% of my roof with EternaBond tape and the areas I couldn't tape (round tank vents) I used EternaCaulk. Both the tape and the sealant have been problem free and the coach is out in the weather 24/7/365.
RV Leak Repair Tapes & Sealants | EternaBond
If you have the budget for it - https://rvroof.com/
Good luck with the project.