Roof Revivers Roofing Services in Central Ohio

What Are Those Ugly Streaks On My Roof?

What are those ugly black streaks on my roof?

Houses in areas receiving the right combination of shade and humidity will tend to see the growth of things like algae, moss, or lichens on the roof, causing roof stains.

Roof algae, commonly known as gloeocapsa magma, is a type of algae that thrives in humid and warm climates. It frequently appears first on the north slope of the roof

roof stain caused by algae

where shade is prevalent and moisture tends to accumulate. The result is unsightly roof stains.

Once attached to a shingled roof, roof algae (also called roof mold) feeds on the dead organic matter used in the manufacturing process of asphalt shingles. They feed on limestone filler in asphalt shingles, grow and darken. As the algae breaks down the  shingle, the ceramic granules protecting the surface of the shingle are loosened and begin to fall off.

Removal of the ceramic granules causes the roof to deteriorate prematurely because it diminishes the roof’s abilities to reflect the sun’s UV rays. Not only are these roof stains ugly, but if they are not treated, the roof algae will reduce the life of your roof, diminish your home’s curb appeal and in extreme cases, increase your home cooling expenses.

Since algae spores are airborne, they are carried from roof to roof. If one house in a neighborhood has black streaks from roof mold and algae, it’s very likely that the whole neighborhood will be infested before long.

moss on asphalt roof shingle

Moss spores are also carried by wind and spread throughout neighborhoods like roof algae. Moss can be detrimental to asphalt shingle performance. Tree branches and other debris on the roof further hold in moisture and act as food source for moss and lichen. Moss can cause the edges of the shingles to curl or lift off the roof, which increases the risk of shingles coming off during bad weather. In severe cases, moss build-up can result in moisture damage to the roof or may even cause leaks.

Beware of pressure washing!

Unfortunately, traditional roof cleaning methods use high-pressure washing and/or hazardous chemical ingredients such as bleach, lye, copper, zinc or acid. While this method may remove roof stains, the concentrated high-pressure jet will scrape off the small pebbles on top of the shingles and will only make your situation worse.

These techniques can damage the integrity of the roof and cause harm to siding, brick, windows and gutters. Even after they’ve dried, these chemicals can leave a residue that can harm children, landscaping and pets.

Roof Revivers only uses algae treatment products that are biodegradable and non-corrosive. We apply this eco-friendly treatment using a gentle “garden sprayer” that doesn’t require rinsing—thus eliminating the need for damaging pressure washing. The result is a beautifully restored roof with no potential damage to people, pets or property!

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