I had an EPDM roof on a 1996 Jayco. The roof was not giving me any trouble, but I thought I would take a belt and suspenders approach. First I gave it a good washing with some dish soap, warm water and a soft broom. Got it clean as I could. Then I gave it two coats of Kool Coat from Camping world, and also used the primer first as directed. I just sold the rig after 16 years and the roof never leaked, nor did the Kool Coat peel or give any problem. A big bonus was it completely stopped the black streaking which the dandruff from the roof contributes to. I think I probably would of had to re-roof during that period without the Kool Coat. It worked great for me, but I followed the directions to the letter.