What Are Those Black Stains on My Roof
The black stains or streaks on your roof are Gloeocapsa Magma Algae, which is often called “Roof Algae”. Roof Algae is most prevalent on a north facing and shaded roof slopes.
Gloeocapsa Magma Algae is a Cyanobacteria Bacteria that feeds on moisture and the limestone used in today’s shingles. Cyanobacteria Bacteria have a bluish tint but develop a dark outer UV protecting coating. It’s this protective coating that stains and streaks roofs.
Why Do I See More Roof Stains Now Than In The Past
Up until about thirty years ago; roofing shingles were manufactured with felt, asphalt and colored stone granules. After that period of time, shingles were made of a fiberglass mat, asphalt, limestone and colored stone granules. Limestone is cheaper than asphalt and was added to make the shingle heavier. The limestone provides food for the roof algae.
Can Black Stains Cause Damage to My Roof
There is very little evidence that roof algae causes damage to your roof but is very unsightly and reduces the curb appeal of your home.
Roof Algae Cleaning Methods
There are many companies that will offer different methods and products for roof cleaning but they are a temporary solution at best. At worst; your roof, gutters, siding and landscaping will be permanently damaged. Often the cleaning products contain bleach or phosphates. These methods and products are a short term solution and the roof algae will return.
Zinc or Copper Strips Installed At the Roof Ridge Will Help Prevent Roof Algae Growth
Over the years we’ve observed that roofs with zinc or copper strips installed on the roof ridges have very little algae growth. Zinc or copper strips won’t kill the algae but will help prevent further growth. With rainfall, the zinc strips leach out zinc carbonate and copper strips leach out cupric ions. These leached-out solutions have prevented further roof algae growth and black roof stains. Unfortunately there is not a permanent solution to clean black streaks from your roof.
With-in the Last Ten Years Roof Shingle Manufactures Have Made Shingles Algae Resistant
Most shingle manufactures today are formulating their shingles with copper-containing granules to be algae resistance for up to ten years. Commonly their warranty provides for a roof cleaning, not a roof replacement. Atlas Shingles are treated with a Scotch Guard Protector, which Atlas claims will provide more resistance to roof algae.
Contact us today if you have roof algae or any roof concerns and we’ll arrange for a free no-obligation inspection.
To see a complete line of our roofing material offerings, give us a call today at 800.798.2950.
At Excel Roofing, we strive to be the best roofing contractor that has built the trust of our entire community. Our reputation is our most important asset and we are proud to be one of the best roofing companies in Pennsylvania, New Jersey and Delaware.
Excel Roofing installs new roofs and performs roof repairs in the following areas:
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