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No-Pressure Roof Cleaning

Have you noticed that the shingles on your roof are forming ugly dark spots and streaks?

Some will tell you that those dark spots, or roof stains, are mold growing on the roof. However, they are actually the build-up of dead algae cells called Gloeocapsa Magma.

You might also notice that the roof stains may appear more on one side of the roof than the other. That is because the conditions in which the algae needs to grow and flourish are typically on the north side of the roof, in areas that get the least amount of sunlight and stay damp after a rain, or from morning dew.

Like all living organisms this algae needs this moisture to survive, but it also needs a food source. The Gloeocapsa Magma algae finds this food source in the shingles on your roof.

Years ago shingles were made from an organic mat comprised of mostly cotton scraps. Asphalt was poured over these cotton mats and was absorbed into the cotton. Afterwards, it was cut into strips known as roofing felt. To protect the roofing felt from the elements, small granules of stone were applied to the topside of the roofing felt. 

Around twenty years ago, shingle manufactures moved away from the cotton mats and began using fiberglass. A filler, crushed limestone, was added because fiberglass did not absorb asphalt. The crushed limestone absorbed the asphalt and added more weight and durability to the shingle material. 

While the crushed limestone was the answer to one problem, it created another problem….. it became a readily available food source for the Gloeocapsa Magma algae to feed off of. We have heard some people say the black stains are only a cosmetic issue and they are not hurting anything, but the truth is, Gloeocapsa Magma algae devours limestone granules that are pressed into the shingles. Eventually, the granules become loosened and you will notice an unusual accumulation of them inside your gutters.


While the premature granule loss is one problem, as the black staining worsens and spreads, the shingles also lose the ability to deflect heat from the sunshine. Inside attic temperatures can soar causing increased cooling bills. Also, the increase in roof temperatures causes the shingles to bake and become brittle. If left untreated these black stains can shorten the expected life of your shingles by up to 30%.


Another issue you may see on your roof is the growth of lichen and roof moss. These organisms attach themselves to the granules on the shingles loosening and dislodging them.

Lichen and moss can also grow up under the edges of the shingles lifting them and breaking the bond of the glue strip on the back side of the shingles making them prone to wind damage and leaking.  


Sea to Summit Pressure Washing can remove the Gloeocapsa Magma algae as well as lichen and roof moss with procedures and cleaning solutions recommended and approved by the Asphalt Roofing Manufactures Association. These procedures prohibit the use of pressure washers to clean the shingles.

The practice of using a pressure washer to clean shingles will void the warranty of all shingle manufacturers. Here is a picture from our Wall of Shame page showing you what you do not want to see on your roof.

For more information about black roof stains and how we can save you thousands of dollars in early shingle replacement cost, contact us on our contact us page or feel free to call us at 864-653-0123. 

Below are a couple more roofs that we cleaned with our safe no-pressure method of roof cleaning.

If you like a free online instant quote for any of our exterior cleaning services please click here.

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