I've got composite shingles on my home that are about 9 years old. They are grey (at least most of them are). I have black spots and streaks on the shingles. Is cleaning them impossible? I'm guessing it is mold. Any ideas?
The ones I've seen around here I think in most cases it is lack of ventilation in the attic. It seems where there is a small vent will stay looking good thats why I put continous ridge vent when we built.
Could be pecan or cedar tree 'crud'?? BUT.. you could try using a power washer.. rent one! OR.. with all the hail storms we have around here.. IF you have insurance..... call em up to do a claim... you might just get a new roof out of the deal.. I DID!! (Darn, I'm glad I remembered I had that policy!!) I was trying to figure out how I was gonna pay for a roof!! It didn't leak.. looked fine.... I just called them out for one little area on my shop/garage building near the flashing!!
I'd say that you have mold/mildew. It is especially noticeable on white to grey roofs. What seems to work is a product called Z-Stop (<--Click link). It is a zinc metal strip that you attach to your roof near the peak. Rainwater washes the zinc down the roof each time it rains. The zinc will kill/prevent the mold and mildew for many years.
I believe there is something called oxygenated bleach that will take care of that.i am a house painter and we have been considering offering that surface when we pressure wash a house.I believe you can get it at the hardware store.
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