Columbus Roofing: Article About Algae Resistant Shingles
At first glance, algae on a roof may appear to be a normal occurrence that detracts from a home's exterior appearance. However, these microorganisms can have a much more serious impact on roofing materials. Algae spores retain moisture and are a source of food for mold. Mold also feeds on roofing tar, causing the protective granules on asphalt shingles to become dislodged. Certain types of mold can also pose health risks to homeowners. Therefore, preventing algae growth can go far in protecting a home's roof as well as the health of the people who live inside the home. One preventative measure homeowners can take to curb algae growth is to install algae resistant shingles, also known as AR shingles. A licensed, knowledgeable Columbus roofing contractor can help homeowners weigh the pros and cons of choosing AR shingles.
The type of alga that inhabits roofs is known as Gloeocapsa magma. Signs of algae on a home's roof include dark spots or streaks that are usually black, dark gray or blue in color. The coloration that remains on the roof is a buildup of dead cells that rub off the algae and accumulate on the shingles. Asphalt shingles were not especially prone to algae growth until the 1990s, when the composition of asphalt shingles was changed to include fiberglass and powdered limestone.
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It was soon discovered that, in warmer climates, algae began feeding on the limestone content of the shingles.
Algae resistant shingles look like common asphalt shingles; however, they are specially manufactured to deter the growth of algae on the surface of the roof. While typical asphalt shingles have mineral granules embedded in the asphalt, AR shingles are embedded with a mixture of copper and standard mineral granules. When algae resistant shingles were first introduced in the 1960s, zinc granules were used. However, due to environmental concerns, manufactures began to replace the zinc granules with copper, which, like zinc, naturally resists the growth of microorganisms. In today's AR shingle product, copper granules usually comprise approximately 10 percent of the granules that present on each shingle. Algae resistant shingles have since grown in popularity and are now a codified requirement in certain jurisdictions.
For homeowners who need to replace their existing asphalt shingles, algae resistant shingles are worth consideration. Although shingles that are specially treated with copper granules may cost slightly more than standard asphalt shingles, homeowners can expect their roof to remain free of algae growth for the shingles' entire life cycle.