What Are Those Black Streaks on My Roof in Jacksonville FL

Get a free estimate!

Complete the contact form to get a free same day estimate today!

    Unfortunately, those black streaks on your roof signal the presence of algae that can damage more than just the curb appeal of your home. That algae is called Gloeocapsa magma, and it can create problems requiring costly roof repairs without prompt roof cleaning in Jacksonville, FL.  The algae can spread rapidly and potentially shorten the lifespan of your roof. Left untreated, Gloeocapsa magma commonly causes harmful effects to your roof, such as:

    • the decay of asphalt shingles after the algae eat the limestone filler within the shingles
    • the growth of lichen and moss, both of which hold moisture on the roofing materials and speed up normal wear and tear
    • the warping, bending, or separating of shingles over time

    If you are noticing black streaks on your roof, you should act quickly to protect your home from expensive roof repairs or replacement.

    How Did This Happen to My Roof?


    Gloeocapsa magma frequently presents problems to homeowners in Southern states because of its ability to survive and thrive in harsh climates. Furthermore, the algae can infest an area quickly because its spores travel easily from roof to roof in the wind or on animals. In fact, the algae spread has even moved into parts of the northern United States and Canada in recent years.


    The algae make the black color you notice on your roof by developing a dark, protective layer for itself that fights against UV radiation from the sun. Small colonies of the Gloeocapsa magma start out in areas of shade or moisture on your roof but quickly spread after feeding on the limestone filler material within your shingles.

    What Other Harmful Effects Do Algae Cause?


    Gloeocapsa magma can end up striking another costly blow to your finances in the form of higher energy bills. The black stains the algae create absorb sunlight instead of reflecting it. As a result, your cooling system must work harder to cool your home because of the heat trapped by the roof. Over time, your shingles will degrade at a faster rate than average because of the excess heat that these stains create.


    Are There Any Preventative Measures Against Roof Algae?


    Sadly, there are no foolproof ways to fully protect your roof from Gloeocapsa magma due to its ability to survive in harsh climates. However, there are a few steps you can take to try to limit your risk of algae infestation, such as:

    1. Consider using algae-resistant shingles when you are roofing your home.
    2. Install strips of galvanized sheet metal, copper, or zinc under the top shingle layer to inhibit the growth and spread of algae.
    3. Remove gutters that drain directly onto the roof, limiting the moisture that promotes algae growth.
    4. Maintain a schedule of regular roof cleaning in Jacksonville, FL.

    Contact Us

    Contact As New Again Pressure Washing today to schedule an appointment or get an estimate on roof cleaning in Jacksonville, FL. Call us at 904-881-9743, complete our online contact form, or email us at We’ll come out and give you a free estimate!

    Recent Posts

    Phone Number
    (904) 881 9743
    Service Area
    Jacksonville, FL, & the Surroundings Areas, Including Orange Park, St. Augustine, & Ponte Vedra

    1433 Romney St #5, Jacksonville, FL 32211

    Hours of Operation
    Monday – Sunday (6:00 AM – 10:00 PM)

    Follow Us
    Scroll to Top