Black Algae On Siding

Black stainsare usually a sign of mildew algae mold or fungus.

Black algae on siding.

Will algae harm your siding. Green stains clean up in 1 2 weeks black stains and moss clean up in 2 or more months. A microscopy lab examination of a sample from this surface would be needed to know for sure. Green algae black mold and moss begin to die off on contact.

Green stainsare almost always the result of algae or moss. You re most likely to see green stains on siding that is inadequately ventilated. Usually appearing as a scaly growth it can grow on any type of siding. Also known as artillery or cannonball fungus sphaerobolus it uses internal water pressure to forcefully fire its spores similar to seeds up to 20 feet away.

But testing is probably not justified. The fungus sets its sights on bright areas so that means it will aim for any pale surface that reflects light such as the siding on your house. The combination of the wind and the rain rinses and scrubs your surfaces clean over time. Fortunately algae on vinyl siding will not affect the function of your siding or cause it decompose.

Black algae can grow there as well as in areas with direct sunlight due to its protective coating. The black stains on the vinyl siding shown at left may be a fungus or a black agae. Clean siding without any scrubbing. However if the algae is left to flourish it could permanently stain lighter colored siding with unsightly green brown or black spots.

By the growth pattern we think this is almost certainly a dark colored algae. Yellow stainsmean you probably have damaged insulation or deteriorating sheathing behind the siding.