Here is what was presented to us at the Good Sam Rally by a commercial roofer who has developed a liquid roof system for RVS. Clean your roof thoroughly. He uses simple green and then power washes to rinse. Scrape off inch by inch all caulk around air conditioners,vents and where the roof transitions down the side. Reapply caulk. Silicone is a no no!! Use externabond tape where necessary. Then use a liquid roof treatment. His website is www.RV-Armor.com
He describes it as a Premium Liquid Applied RV Roof system with Lifetime Material &Labor warranty. Only available through certified dealers. Our price was for a 25ft rubber roof @$2500.00. I will be looking on the internet for a do it yourself liquid material. I remember a recent back post about a green liquid that was applied to your RV roof.