Alpha Systems made the rubber roof on my trailer. On their company website, they recommend using Top Job or Spic & Span to clean their roofs.
Miles Away wrote:
Several RV dealers recommended to me that I wash the rubber roof with plane powered TIDE detergent. I tried it and it works great, but be careful because it is VERY slippery. Wash the roof first and keep the side of the trailer wet to avoid letting the run off streaks from staining the sides. Then wash the rig with any good cleaner, except tide because it will leave a powder residue on the gel-coat. I would avoid using a pressure washer.