Danger sign? (picture of roof)

I see roofs like this once in a while, that have what look like stains on them.

Is that a danger sign - that there's mold or bad drainage? Or do roofs just get dirty like that once in a while?

I'm sorry it's such a silly question, I honestly have no idea. If the stains are green, I start to worry about mold and maybe that there is too much shade on the house.

Re: Danger sign? (picture of roof)

could be pollen from the two big trees in front...

Re: Danger sign? (picture of roof)

that actually looks like water damage and its close to the chimney which makes me concerned.

Re: Danger sign? (picture of roof)

i think it could be soot coming from the chimney, which could mean the oil burner is bad.

It also probably means the roof is old - time for all that stuff to accumulate on it.

Re: Danger sign? (picture of roof)

depends on the age of the roof and the quality of the shingles. Some wear faster than others and stain easily.

Re: Danger sign? (picture of roof)

that is a white/grey blend 3 tab asphalt shingle, they are not popular at all in this area now because they age much quicker than other colors. If that is the first layer of roofing on a house that age there is almost certainly water damage to the sheating(wood), not the worst thing in the world, but more more $$ than just roof shingles.
We have a few small spots that look a little green on our roof, but the benefit from the trees keeping the house cooler outweighs the cons of the roof getting green. Now when you see moss growing on a roof, that's a problem.

Re: Danger sign? (picture of roof)

I think its from the trees- that its if its green and not black I cant tell- an inspector would prob reccomend cutting back the trees- and Im pretty sure it can be removed if its just from the trees

Message edited 11/29/2006 4:21:24 PM.

Re: Danger sign? (picture of roof)

It looks to me like roof algae which is quite common on LI, especially on shaded and north facing shingles.

Roof algae treatment

Re: Danger sign? (picture of roof)

DH a roofing/siding/general contractor said that because it is black it looks like galvinization. The nails have been exposed to water and seals are failing on the shingles. Of course he can't be sure because he doesn't know where the trees are and how far they hang over but he said that the black stains is a bad sign.

Re: Danger sign? (picture of roof)

oh jeez! that looks terrible! it's probably in need of being replaced.

Re: Danger sign? (picture of roof)

our roof looked like that because of the trees we had hanging over it...we cut the trees back and my Dh scrubbed the roof and it looks much better....its not necessarily water damage....

Message edited 11/29/2006 7:21:05 PM.

Re: Danger sign? (picture of roof)

Thanks everyone. I guess it all depends, and the professionals need to check it out just in case!