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Northern WI 715-490-3043

Remove Dark, Black Streaks from Your Wisconsin Roof

Does your roof appear dark, wet and streaked? 

If your shingles appear dark and damp or your roof has black streaks on it, you are most likely suffering from a type of algae called gloeocapsa magma. This algae is blown through the air and settles on roofs to feed on the crushed limestone that is a component of most asphalt shingles. Algae grows best in warm and humid climates, so the north side of your roof is most likely to suffer from this issue because it receives the least amount of sunlight throughout the day. Trees that provide shade and gutters that allow water to drain on the roof can also contribute to the problem.

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Roof Algae Causes Damage

Roof algae is generally thought to be harmless, but over time it can cause the UV protective granules on your shingles to come off. This opens your shingles up to sun damage and is why roof algae can be harmful in the long run. Repeated cleaning with harsh chemicals can damage to the roof. In any event, the algae is unsightly and can be removed with a simple cleaning.

Can I clean the algae myself?

People do clean their roofs with all sorts of homemade and store-bought concoctions designed to kill the algae, but this can void manufacturer warranties and actually cause more damage to your roof. Applying cleaning solutions to the roof can be a dangerous taskyou have to be up there for a while, and the wet solution will make the roof slippery. Additionally, certain chemicals can hurt landscaping and other plant life near your roof. When it comes to your roof, it is always safer to go with a professional. Whatever you do, never attempt to clean your roof with a power washer. 

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Can algae growth be prevented?

In short, no. Algae growth cannot be completely prevented. However, installing a copper or zinc strip at the apex of your roof can act as a natural deterrent because rainwater washes trace amounts of the metal down the roof and kills the algae. In more extreme cases or if you need to replace your roof anyway, shingles infused with copper can work to prevent the algae from taking hold. If you need an inspection or are interested in either of these solutions, contact us today for a free quote.