We have a black 2006 Tourmaster motorhome that gets white streaks on the sides every time it rains.  I power washed the roof and really didn't help for very long.  The roof is a white rough textured fiberglass.  I don't have a clue of what to do to stop this mess.  Any help would really be appreciated.

Thanks

I am by no means an expert in any sense of the word, but I will offer my two cents worth and you can determine if it is worth only one cent. :)

I have a rubber roof and I have been told to never power wash the roof. It may be that when you powerwash your roof (if it is rubber) that you are loosening the components that bind the rubber and that is your white streaks. Just my offering for your consideration, I am sure there are others here that will have a more experienced opinion....

Doncat

We were just saying that. The roof was fine last year now we have this issue. The only thing we did different is power washing the roof and the coach was sitting in the AZ. sun for 5 months (along with 50,000,000,000 other coaches).

Common fiberglass dilemma. I don't know the solution. I'd go to a marina/boat-yard and ask them or check out a couple marine forums.