If you’re wondering how these black streaks appear, it’s actually quite simple. Blue-green algae are spread through the environment. These spores can spread from roof to roof if a gentle breeze blows. Spores are small so it doesn’t take much for them to travel a distance. Once these spores have settled they tend to accumulate quite quickly. Algae likes to grow when the conditions are just right. In environments where the air is hot and humid, algae will multiply making your roof its final resting place. If your roof is in an area that is heavily shaded by trees, it may create opportunities for algae growth. Algae breeding grounds are typically shaded areas, so unless you decide to cut back your trees, your roof may fall victim.
Discoloration from algae typically happens on the side of your roof facing the rising sun, or the east-facing edge. Black streaks appear due to algae’s own defense against the sun. This coating has a dark pigment for protection and will easily stain when left to sit atop asphalt shingles.
Roof algae can affect your home in many ways. The most obvious issue caused by the algae is a diminished appearance. In addition to being an eyesore, it can actually decrease the value of the home. Roof algae could be a sign that your roof’s integrity is compromised which may cause homebuyers to try and negotiate asking prices upon inspection. Algae can also cause permanent staining and wood rot, damaging your roof and possibly lead to other problems such as mold. Once algae become a large enough problem that it turns to mold, it can begin to jeopardize the health of you and your family. All of these factors can give any homeowner a headache.
Although algae are pesky, frustrating, and expensive, there are ways to combat them. There are treatment options available, but they may cost you. There are do-it-yourself options, however, they could further damage your roof; damaging shingles, or getting moisture trapped inside your roof. If you find yourself with algae growing on your roof it’s best to employ professionals to tackle the problem.
In addition to dealing with the problem, there are ways you can prevent algae from landing on and staining your roof. Cutting back large branches to ensure enough sunlight reaches your roof is one option to prevent algae from taking up residence in your home. Regular maintenance and roof cleanings are another option to save your roof or you could pay a little more for algae-resistant shingles.