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Home & Garden

Dealing with Moss & Algae Growth on a Roof

By August 18, 2015October 17th, 2023No Comments

Homeowners who live in all parts of the country can experience moss and algae growth on their roof. This growth occurs on many types of roofing materials when there is enough moisture present from moderate rainfall and/or high levels of humidity. Moss and algae are most common on north-facing portions of a roof, since this angle tends to receive less direct sunlight and stay damp longer. Large trees that shade the roof’s surface in any direction can also promote the growth of moss and algae.

“Will This Damage My Roof?”

Of these two kinds of organic growth, moss is the biggest concern because it can shorten the lifespan of a roof. The thick growth holds moisture on the roof surface, speeding up wear on the shingles and contributing to the freeze-thaw cycle in cold weather. Eventually the shallow roots of moss will penetrate the roofing material, promoting rot and deterioration.

Algae feeds on microscopic amounts of limestone filler contained in asphalt shingles, growing and darkening into unsightly black stains. Algae growing on a roof surface is primarily a cosmetic concern due to these dark stains. Do not attempt to get rid of algae stains by cleaning your roof with a power washer, which can damage or break shingles, or apply chlorine bleach in an attempt to kill algae or moss. Bleach can discolor roofing materials, kill the vegetation around your home and speed up the corrosion of metal gutters, downspouts and metal gutter guards.

Cleaning and Prevention of Moss & Algae

Cleaning roofs can be dangerous work. If your roof has developed moss and algae growth, it is best to contact a roofing professional who can apply non-toxic solutions to safely remove the growth without harming the roofing material. A professional can also take preventative measures to prevent reoccurrences of moss and algae.

For more information about metal gutter covers installed by a Gutter Helmet® dealer, call (800) 824-3772.