Ever see stains like this on a rubber roof?

[Chazman]

I'm getting ready to recoat the roof on the Apex (with Heng's) and these stains are imbedded in the rubber. I tried Dicor roof cleaner and Star Brite mildew stain remover. The stains laughed. I'm not really too concerned that they won't come out, but would like to hear your thoughts. Have you ever coated over stains like this? I'm hoping that two coats will cover them, but again, not really concerned about looks, as long as they don't create a problem. BTW, the Star Brite did a much better job of cleaning the roof and I'm considering using that pre-coat. Of course I would rinse it thoroughly, but does anyone have anything to contribute on that as well?
TIA...

[SeaDog]

That doesn't look good. My first thought was mold however you treated the roof for that. I wonder if it could be the chemicals leaching out of the rubber covering sort of like what happens with vinyl in these rigs.

[Chazman]

Originally Posted by SeaDog

That doesn't look good. My first thought was mold however you treated the roof for that. I wonder if it could be the chemicals leaching out of the rubber covering sort of like what happens with vinyl in these rigs.

Thanks for your reply. I think that's a good possibility. I almost thought it was supposed to be there, some sort of design(?) but knew better. There's more of it on the back half, which made me to think the trailer was parked partially under a tree. After cleaning I even tried scraping it a little with my fingernail. It's permanent. Really hoping it doesn't cause problems after I recoat...

[TitanMike]

This looks like the roof on my old TT (a 95 Terry) with EPDM roof membrane.

Same issue, couldn't clean the spots off with anything. Turned out the spots were really the black EPDM showing through the white coating. A good cleaning with an acceptable roof cleaner and application of the new coating should handle the problem just fine.

Even if it was a mold/mildew problem, applying the coating after a couple of days of drying in the sun would merely encapsulate the mold/mildew. If the spores can't get water or light they can't grow so should be no problems.

That said my guess is just "holes in the coating" of the old roof.

FWIW, my TPO roof doesn't have this problem. Any spots are just dirt and they wash off easily with Dawn, Water, and Soft Scrub Brush.

[Chazman]

Originally Posted by TitanMike

This looks like the roof on my old TT (a 95 Terry) with EPDM roof membrane.

Same issue, couldn't clean the spots off with anything. Turned out the spots were really the black EPDM showing through the white coating. A good cleaning with an acceptable roof cleaner and application of the new coating should handle the problem just fine.

Even if it was a mold/mildew problem, applying the coating after a couple of days of drying in the sun would merely encapsulate the mold/mildew. If the spores can't get water or light they can't grow so should be no problems.

That said my guess is just "holes in the coating" of the old roof.

FWIW, my TPO roof doesn't have this problem. Any spots are just dirt and they wash off easily with Dawn, Water, and Soft Scrub Brush.

Thanks for your reply Mike. That's reassuring for sure.

[Scheinin]

I have the same stains on my roof. Since they are even throughout the 40 feet of roof, I am not concerned.

[Chazman]

Originally Posted by Scheinin

I have the same stains on my roof. Since they are even throughout the 40 feet of roof, I am not concerned.

Thanks for your reply Steven. Any idea what the cause is?

[Scheinin]

Originally Posted by Chazman

Thanks for your reply Steven. Any idea what the cause is?

No idea. But they just seem cosmetic, and not effecting roof performance.