Courtesy Dicor Products
RV owners should get their roofs cleaned at least twice a year to prevent damaging substances from getting too embedded and creating permanent stains. This also will help avoid mold and mildew that grow on organic matter attached to your roof. Especially if your RV is parked under trees for extended periods of time, your roof can be a ripe target for bird droppings, mulberry stains, tree sap, mold, mildew, fungus and the like.
For your cleaning technique, we suggest cleaning one manageable area at a time, such as a 3′ x 3′ section.
First, rinse the area with a hose or a power washer with a wide pattern nozzle and let it drain. Then spray on the cleaner and scrub with a medium bristle brush. Then rinse and move on.
If you are on the roof doing this, start in one corner and then move sideways to the other side and then down and sideways again to the side where you started and so on, working backwards to the other end of the RV. But be careful! Note that by working in such manageable areas, you can also handle the whole job from a ladder or scaffold without getting on the roof.
Lastly, if you have some stubborn stains, you can try mineral spirits, but with a BIG CAUTION: Do NOT use mineral spirits unless you carefully follow these directions. Mineral spirits is a petroleum distillate, and a rubber roof can react with swelling, deterioration and discoloring.
DIRECTIONS: NEVER pour the mineral spirits DIRECTLY ONTO THE ROOF! Always pour a SMALL amount on a soft cloth (less is best) and then use the cloth to scrub out the stain, using only as much as needed and wiping it up with another cloth when the stain is gone.
[Editor’s note: This information is provided by roof membrane manufacturer Dicor. While there’s plenty of "promotion” for their product included, some of the information and principles may be of assistance to our readers.]