It was recommended to me to use " Through the Roof ". I believed the more it cost the better. The product may be great. I bought a gallon knowing it would cover the entire roof. Well, lesson learned. Before I go any further, I am not putting down this product as I have just finished using it. Here is the problem I ran in to. I have a thirty-six foot RV. When applying this product you cannot roll it as it has to be around 1/8" think. As I starting applying, I realized I was running out of it quickly. I made the decision to only do penetrating areas and use a product that I could roll on. I am going to look here for additional information on products. Note: not always is the high price items always the best.
I have always preferred the in layers approach, after trying the top of the line expensive stuff. I found a few products that work well and cover well applied in layers and not costing you a 2nd or 3rd morgage.
When re-coating a roof, and I've done many of them. My first step would be after cleaning it especially every nook and cranny would be to use self leveling Dicor. it seeps into any hole or crack and starts to set up and expands sealing any infiltration spots. It is like a rubber roof in liquid form and is also recommended for repairs of those types of roof repairs also. Then and only then would I start looking for a product to re-coat. If you follow my advice pay particular attention to all areas attached to the roof with screws. I'm just a retired RV Technician and I only comment on what I know works and used for years. Dicor cost depending on who you buy it from between $8 and $10 a tube and if applied by a standard caulk gun. your size RV should use about 4 or 5 tubes. And will seal up any leaks both current and leaks in progress. Anything you put on the roof after sealing it with Dicor will just make it look pretty and protect it from further weather related attacks.