What are these stripes in my roof ?

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  #1  
Old 09-12-16, 02:02 PM
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What are these stripes in my roof ?

[B]My house roof has these....what .look like huge Drip marks that fan out towards the gutters 6-8 stripes each side of roof. One guy that says power washing them can take them out. Man!! we don't even know what they are from.The pictures don't do them justice, but look real close they are dark in color .Look like something that would come from something dripping off branches from up aways up on the tree. Thats about all i can tell you. Its this way on 50%of the roofs i see each day.driving around.Any ideas?????????? thank you bob s/B]

btw this was a brown roof my garage don't show these ps the power wash offer sounded a bit far fetched.to me but plusable
 

Last edited by bsa_bob2; 09-12-16 at 04:07 PM.
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Old 09-12-16, 02:09 PM
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Don't see any pics (http://www.doityourself.com/forum/el...-pictures.html) but I would guess moss.
 
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Old 09-12-16, 03:13 PM
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Stains can be from multiple things. Tree pollen, mildew, asphalt residue from the shingles themselves. No way to know without pics... even then we might be guessing.
 
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Old 09-12-16, 03:59 PM
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Sorry i have pics. they don't show up to well -and my wife don't want me on the roof . hth bob s and thanks


the bottom shot is camera angle error .Its making the lines way to many, but to the rightside of the top picture just imagin 5 or 6 of those all start in the same measurement from the top.This A custom built house in the 70s with 2x6' boards on 12" centers for the angled supports to the peak....if this helps thanks again Bob S i'd forget my shoes i think if she wasn't here
 
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Old 09-12-16, 04:19 PM
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Yeah, the zinc in your galvanized flashing creates electrolysis when it rains, which creates clean spots on the roof where mildew, moss, lichen won't grow. If you want to know more, just Google: why do zinc strips on a roof work?

Some people will install zinc strips all across their ridge / or protruding out from under the ridge cap to keep the roof looking clean. Crazy, I know, but it really works.
 
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Old 09-13-16, 06:03 AM
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Some people will install zinc strips all across their ridge / or protruding out from under the ridge cap to keep the roof looking clean. Crazy, I know, but it really works.
Did not know this. Very interesting. Learn something new on this site quite often.
 
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Old 09-13-16, 07:06 AM
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OK! i see what you are saying..but would it clean up the "already there marks'i'll look that up thanks xsleeper bob s
 
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Old 09-13-16, 07:45 AM
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It's hard to tell from the angle the pictures were taken from but it appears you have the same stripes on the front where there are no penetrations (no zinc). Also you roof looks like it gets good sun...so...probably not moss & lichen growth. I think your roof is just getting old & this is one of the symptoms. As the roof ages the top aggregate layer that protects the asphalt erodes away & exposes more & more of the asphalt beneath.

Power washing would only strip even more aggregate off & accelerate the wear on the roof.
 
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Old 09-14-16, 08:14 AM
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thanks guy48065. This roof is 11-12 years old i guess, hope i don't have to replace it already. But You are correct in what you say.plenty of sun........and i'm glad you stopped my "powerwashing it. I might have been doing more bad than good. bob s
 
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