Black streaks on house and garage

I am looking at having a complete tearoff on my house and my garage. I have gray shingles however on one side of my house and one side of my garage I have long black streak marks. I think they are from moss or algea growth as our yard is pretty shaded. My boyfriend is insisting that they are from the shingles being older, water running down them etc etc. Right now we deciding between two bids. One wants to use zinc stips the other says we do not need them. Could the black streak marks be from something else beside moss or algea growth? I am confused because one company says we need the strips and the other is insisiting we do not. Can anyone give me some feedback on this. Thanks :smiley:

the marks are from algea and mildew…and the run of water causes them to streak like that. the color of the shingle contributes to how much this is noticable…the lighter the shingle the more you see. they have algea resistant shingles. talk to any building material supply house to find what is recomended in you region.

The Roof Stains are typically black algae that is feeding on the limestone in the shingles. Its been happening all over the country since the late 1970’s. Like all algae (bacteria) it gets smarter each year and has become more hardy. The Roof Stains can be cleaned using a purpose designed roof cleaner. There are a couple types out there. And depending on which type the company sells, they’ll claim its better.

First and most hyped is the Oxygen Based non toxic cleaner, its environmentally safe, and great for home owners eventually it gets the job done.
Second and less hyped but full strength are the hydroxide based cleaners. Its the fastest choice for someone who knows what they are doing, and wants the job done fast. Typically a professional who cleans roofs for a living.

Several companies sell the one or the other products.
But I’ve found that CleanerToday is the only company that carries BOTH types of cleaner (Oxygen and Hydroxide). The prices are the best out there, and if you email they will typically match competitor’s pricing.

Best of all, if you start with oxygen, and want to upgrade to the contractor grade, they tend to give a repeat customer discount.

Check them out at Cleaner Today:

Coupon Code “SHIP” used to get free shipping (not sure if it still does).

Roof Stain Revelation!

i dont beleive in the metal strips. works for a couple feet below them and thats about it.
get your self a 5 v crimp galvalume metal roof.
shouldnt be much more than a good shingle.


Well, I say get the AR shignles AND have the zinc, copper, or aluminum strips installed. The AR shignles will do their job for about ten years or so, and the metal will take over from there.

Unlike gwedo, I know that the water flowing over the metal works much better than he stated…just go around and look at houses with algae on the roofs, and look underthe vents, metal chimney, pipe leads, etc…the stains arent present where the oxidization has taken place from the water flow over the sacrificial metals.

i have the same mildewed shingle roofs with the same boots, vents, etc. with the same little, i repeat little, areas of clear shingles below.
the bottom line is nobody uses the strips down here cause it doesnt work.
keeps the algee/mildew off for only a couple a feet down then it starts formin again.

call em like i see em.


did you guys actually leave some of the zinc strip exposed? LMAO

The black Streaks on shingles all across the country is likely caused by a form of algae that feeds on the limestone in the shingles.
This algae can be CLEANED. You don’t need to replace the roof unless it is damaged, or nearing the end of its useful life.

Cleaning roof shingles should be done with care, as should anything done on a ladder.

There are two formulas of roof cleaner that work great. Roof OX and ROOF QSE. The QSE (Quick Simple Effective) is the stronger of the two, and is meant for extreme home owners, or contractors.

Both are safe, and do not contain chlorine bleach ( which dries out shingles).

You can find prices, and plenty of educational information at CleanerTODAY. com to learn more.

But wait!!!

There’s more, order today and get your handy dandy spray cleaner bottle brush for only .99 cents.

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Im gonna go take a pic of two houses across the street from mine with black algae streaks, and you all can be the judge in the matter of…do the metal accessories kill the algae down the roof or just a couple of feet…To be continued. 8)

I think this should settle the issue. Forget the cleaners…install a permanent solution…zinc 8)

Hi Aaron,

Nice neighborhood.

Thanks, Lefty.

That white vinyl fence has gotten vandalized twiec since they put it up last year… :frowning:

I am going to treat it with an aliphatic white polyurea anti-grafitti coating if they will allow me to. Good for the neighborhood, good for the neighbor relations, good for the portfolio. Everybody wins.

hey Aaronb,
well ill give ya that one.
even though that mildew isnt very thick.
mildews alot thicker here and the mildew forms again a ft or two below the chimney or vent or .
a chimney or vent will not prevnet mildew from formin all the way to the bottom of the roof like the house in your picture
were im at zink strips just dont work.
nobody sells em.
nobody puts em on.
metal zinc strips came and went years ago in tampa bay florida.

but ya got a good picture, so ill give ya that one.