Black streaks on your roof are typically caused by algae growth, particularly a type known as Gloeocapsa magma. The algae forms a protective, dark coating that shields it from UV rays.
Your roof makes up a large portion of your home’s exterior, and black streaks will certainly dampen curb appeal. The algae might not damage the shingles, but the reason it is growing could be an issue.
What Causes the Black Streaks On Your Roof?
This type of algae thrives in humid environments and spreads through airborne spores, feeding on the limestone filler commonly found in asphalt shingles. Areas where moisture accumulates, like gutters and low-hanging trees, are the perfect damp environment for algae growth.
While the streaks aren’t necessarily damaging to your roof, they don’t look great.
Humidity and Moisture: Algae thrive in warm, humid conditions, especially in areas with little direct sunlight or poor drainage.
Roof Material: Asphalt shingles, especially those with limestone, provide an ideal surface for algae growth because the limestone acts as a food source for the algae.
Geographic Location: If you live in an area with high humidity or frequent rain, your roof is more likely to develop black streaks due to algae.
How to Get Rid of Black Streaks On Your Roof
Algae can be hard to remove, but not impossible. Here are some tips and tricks to help you get your beautiful roof back.
Roof Cleaning Solutions
Pro Tip: Don’t use a pressure washer, as it can damage the shingles.
Use a 1:1 mixture of bleach and water to kill the algae. Spray the solution on the affected areas and let it sit for about 15-20 minutes before gently rinsing it off with water.
This mixture can damage plants, so cover them before applying it to your roof.
Hire a Professional
A professional company can assess your roof for algae and other maintenance issues. They have the knowledge, skills, and equipment to clean your roof effectively and safely.
Trim Back Overhanging Trees
Shaded roofs retain moisture longer, creating the perfect environment for algae growth. Trimming trees that overhang your roof will allow more sunlight to reach the shingles, helping to keep them dry and reduce algae buildup.
Low-hanging branches can also damage your shingles and clog your gutters, so trimming them serves more than one purpose.
Install Algae-Resistant Shingles
If you’re planning to replace your roof, consider algae-resistant shingles. These shingles often have metals like copper-lined mineral granules, which help prevent algae from growing in the first place. If you are looking into a roof replacement, algae-resistant shingles could be a smart investment.
Preventing Black Streaks
Once you’ve removed algae from your roof, the goal is to stop it growing back.
Regular Maintenance: Keeping your roof in tip-top shape is the easiest way to prevent algae growth and other maintenance issues that can damage your roof and underlying structures.
Improve Ventilation: Make sure your roof and attic are well-ventilated to prevent excess moisture buildup.
Zinc or Copper Coatings: Look at modern roofing products with pre-applied zinc or copper coatings that help prevent algae growth.
Trust Style Exteriors to Care for Your Roof
Style Exteriors is a family-owned operation committed to enhancing the comfort and value of your home. When you choose us, you choose a company that values quality, integrity, and community. Your home is your sanctuary and a source of pride. It can be disheartening to encounter maintenance issues or unsightly algae growth. Luckily, there is a fix (sometimes big, sometimes small) for most problems. So, if you have black streaks on your roof or any other roofing issues, contact us today for help.