I have a 1992 Thor Pinnacle Motor Coach. The roof is a rubber membrane. There have only been two products used on it, pasted below: 1) New caulking every 3-5 years with "Through The Roof" (Minimum order is a case of 12 tubes. My last case cost me $63.50.) at: http://www.sashco.com/home_improvement/products/throughtheroof.shtml This product only comes in 'CLEAR' and should be applied in a well ventilated area. The only drawback is that it remains flammable during the 24 hour cure time and you have to wait 24 hours to apply a latex paint and 1 week to apply an oil based paint. It will adhere to wet surfaces, it's UV sun exposure resistant, it won't become brittle, it stays clear and waterproof and remains flexible with fixtures in constant dynamic motion. It's the only product I'll use. 2) A single coat of sealer every 2-3 years with "Rust-Oleum Professional 7792 Gloss White Enamel" -- currently purchased at Lowe's for $22.50 a gallon (one gallon covers almost 600 square feet). The only drawback is that it cannot be applied unless the humidity is below 85%. Also, it should be applied to a level RV and allowed to dry for at least 2 hours before moving. It dries to the touch in 2-4 hours and totally cures in 5-10 hours. Note: The below pasted personal cleaning solution is all that I use 2-3 times a year. Cleaning solution: 1 gallon water 1 quart bleach (household) 1/4 cup Fabric Softner (any cheap one you can find) - Start washing from bottom to top and front to back. - Soft scrubrush a 16 sq ft area gently, then rinse. - Soft scrubrush the same area gently again and work solution in with terrycloth rag (old bath towel), then rinse. - Repeat until all four sides are complete. - If roof needs washing, use a cotton mop. Start from the front and work to the rear of the unit, cleaning approximately 16 sq ft at a time, until done. Note of caution: There are only a very few roofs that can be walked on. Placing a 1" thick piece of plywood from side to side is recommended in order to support one's weight while cleaning the surface or while doing repairs/checks.