# What causes the black streaking?



## krgalligar

Does anyone know the actual scientific reason for the black streaking, other than it's just a sign of hail damage what actually causes it and has been proven?


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## apkole

Google . . . shingles algae staining . . .

My guess is that there's some good info out there somewhere.


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## Pie in the Sky

Not a sign of Hail damage... (at least I hope not)


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## RackCityRoofer

Black streaking is caused by an air borne algae it only grows on the north side of the roof. 
hail does contain chemicals that in theory could clean the algae off the roof when it hits.... so look for clean spots .....


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## shazapple

Area's below a piece of metal are typically clean because small traces of metal wash off and kill the algae (copper is a good example of this)


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## Interloc

lead works as well.


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## larryb

krgalligar said:


> Does anyone know the actual scientific reason for the black streaking, other than it's just a sign of hail damage what actually causes it and has been proven?


The black streaking is not a sign of hail damage. If you make that claim to even an inexperienced ins adjuster, you're probably gonna at least get the look. 

Usually occuring just on north facing elevations, there are special chemicals that are designed to clean off the algae. Good to know how to do that and offer that service for those potential customers who don't need a new roof and only need a cleaning. If they want a new roof, sell it to them but if they don't need it, at least offer to clean it for them and you'll be the first one they call when they actually do need a new roof installed.


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## Pie in the Sky

RackCityRoofer said:


> Black streaking is caused by an air borne algae it only grows on the north side of the roof.
> hail does contain chemicals that in theory could clean the algae off the roof when it hits.... so look for clean spots .....


"Acid Hail"


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## vtroofing

It is Algae. So like it has been said metals assist with a chemical reaction reducing this effect. Most Manufacturers have added AR to their shingles by either including metals (zinc or copper) in their ceramic granules, or washed with causing the same effect. 

Bouncing slightly off course- GAF's claim to Advanced Protection Technology they have reduced Limestone- (Lime being a food for Algae) also reducing weight.


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## roofermikeinc

*algae/fungus remedy*

Down here in Miami, roofers are constantly wrestling with the algea and fungus problem .The streaking is probably caused by dead algae as it's washed off. And where there's dead alae, there's ... 
Don't use bleach. There are some safe roof cleaning chems out there.
I never bothered with roof cleaning unless I was applying an elastomeric. On South Florida roofs the stuff comes back in 2 -3 years. Maybe up there a cleaning lasts longer.
I found a roof cleaning and sealing system by Simix Solutions that works. Their cleaning powder is really just an oxy cleaner with some 
proprietary goodies. Make a strong solution of Chlorox II(the first oxy) & H20 and you've got....hydrogen peroxide! Safe and effective.
Simix's sealers are wicked-cool, however. $315/5gal. wicked cool.
It's a tough sell but it works. They did Dolphins Stadium in '06 and it's still clean. 7 year warranty. They say it lasts a lot longer but they don't want to debate what's algae and what's dirt...

pssstt...roofing is regional...

Simix OWES me...


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## vtroofing

pssstt...roofing is regional...

So true.


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## krgalligar

Thank you everyone that is one more question off the list.


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## topviewroofing

Roof shingle stains are often caused by black algae, bleed-through or extractive bleeding of asphalt, dirt, soot, or organic debris.Black streaks on shingles caused by algae or fungal growth used to be limited to warm, humid climates, but now this can be seen on houses as far north as Canada. Some experts attribute the spread to the increased use of crushed limestone as a filler material in asphalt shingles.


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## vtroofing

Some experts? I agree, however having a hard time finding documentation/ proof. If you find any please post.


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## Interloc

topviewroofing said:


> far north as Canada.


 :laughing:


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## Roof Cleaning

I agree with roofermikeinc - Don't use chlorine-bleach The risk to humans, pets, and landscaping is just too great. Zinc and copper tend to retard the growth of roof algae, which is why you'll sometimes see roofs that are mostly covered in algae, with a section under a zinc pipe looking clean. The limitations of zinc and copper are that once the algae growth is there, it won't make it go away. The roof needs to be cleaned for that.


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## Dallas-Roofing

It is a sign of algae. Some of the newer shingles are algae resistant now. However, you can still find black streaks on roofs due to the painted accessories or rust from nails. Although they would not give a black color. But it is definitely not a sign of hail. Matter of fact if you have a roof with algae that you think may have hail damage. You should look for the white circles that the hail would have chipped during impact. Then look and feel to see if it actually caused damage. 

Devin Mahdi
Dallas Roofing Contractors


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## MattAngelly

*Black Streaks*

The black streaks are caused by an airborne algae that grows in the small spaces between your homes shingles. 

You can read all about how to prevent algae on your roof here... http://www.solomoncontractingstl.com/FAQRetrieve.aspx?ID=50270&Q=

http://www.solomoncontractingstl.com


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## OldPro

A good question to have answered is - where do you live? Also, can you post pictures?


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## roofermann

michelclarke said:


> Black streaks on walls and ceilings are a perplexing and difficult problem to diagnose and solve.
> 
> 1. Soot (small carbon particles)​ 2. Mold​ 3. Dirt
> 
> 
> 1. Soot comes from incomplete combustion of a carbon-based material. Any material that can burn can produce soot, including natural gas, LP, wood, oil, candle wax, gasoline, diesel fuel, tobacco smoke, dust, dirt, cooking oils, and carpet fibers. Sources include:​ * Unvented fossil-fired heating appliances, such as space heaters, kitchen ranges, and clothes dryers.
> * Vented fossil-fired heating appliances that experience vent failure (often intermittent and sporadic).
> * Candles (scented candles might be worse).
> * Fireplaces
> * Tobacco smoking
> * Environmental contaminants (dust, dirt, and cooking oils)
> * Carbon from vehicle exhaust in attached garages.
> * Outside sources (factories


This has zero to do with streaks on a ROOF!


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## Masterbuild

I Have found that washing the black algae with a mixture of trisodium phosphate, bleach, and water will remove stains.


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## Maxon100

Ya it's just a type of algae, some people try to use zinc strip to help fix this problem but I just use a 1200 psi powerwasher to remove any moss or algae stains. Takes a few hours and the roof will look brand new.

http://stormproofroofing.org/


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## valleypeakroof

The black streaks you see running down your roof are a hardened form of algae. The algae are actually feeding on the limestone particles in the shingle. Over time the algae will trap moisture underneath the shingle, causing pre-mature shingle aging and most significantly, granule loss! This does not always mean your roof is ready to be replaced, but it will only get worse each year. 

TIP: consider purchasing an algae resistant shingle for your next roof or install zinc or copper strips to defend the algae growth.
Roof | Valley Peak Roofing


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