Roof question

[Quiroule]

While washing the roof of the FW, I noticed that most of the roof is light gray but there is a lot of dark gray spot big as a dot to the size of a dime.

Is this a sign that the membrane is deteriorating.

Thanks

[Mikendebbie]

I would guess those are more likely to be a stain - not a sign of deterioration...but that is only a guess. I would be tempted to put my thumb on the dark spot and wiggle it back and forth just to see how it reacts - then do the same with a non-spot section. If the reaction is the same then I would think the membrane material is not affected or deteriorated. Just a thought...I am not a roofer!

[gearhead]

My guess is it's mildew.

[Vet4jdc]

Mildew!