Spots on roof

[Challenged]

Here is a photo of my roof. I think it is rubber over fiberglass. Is this something white flaking off, or what is the problem and how do I fix it?

[bsmith0404]

That looks like the very typical mold that we see on roofs. Get a good roof cleaner and sealer from your RV dealer or on line. You can also use other methods...do a search on this site for roof cleaning.

[Festus2]

Sure looks like mold to me ---- black/gray spots on a white roof. Unsightly perhaps but won't harm the EPDM rubber below it.

[JRTJH]

Yup, simply mold. You're probably parked under a tree? The "cheapest" and one of the "easiest" ways to clean it is (on a cloudy day or in the shade) to take 1/4 cup of Dawn dishwashing detergent (the blue kind) and 1 cup of Borax, mix in 1 gallon of warm water, rinse the roof with cool water, apply the soap solution with a "medium stiffness" scrub brush, let it sit for about 30 minutes, then scrub again and rinse well. Make sure you also rinse the RV sides as the soap will streak the sides if left on for any length of time.

Once done, most of us use Goodyear Aerospace 303 and apply a liberal coat to the roof membrane.

Good Luck,

Oh and your comment "rubber over fiberglass" The roof is EPDM (rubber) over OSB (probably3/8" thick)...

[therink]

Yes, mildew and likely tree sap. I would use 5 percent bleach solution with water and dawn detergent, a medium bristle deck brush and go to town. Rinse off rreal well and brush wash the sides with dawn solution. That is what I do.
The only difference is that I try not to let the roof get that bad, leading cause of black streaks on the sidewalls.