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Mold, Mildew, Algae

Mold, Mildew, and Algae Growth on Your Roof

There’s a fungus among us…but there doesn’t have to be.

Mold and mildew love dark, dank places—so what’s it doing on a roof out in the sunlight?

Mold, mildew, and even algae thrive in wet environments, so if you see it on your roof, you likely have issues with water saturation.


Algae spreads via spores that float through the air and land on your roof. Algae needs both moisture and heat to grow, making a wet roof the perfect spot. Algae also needs nutrients, which it gets from the inorganic materials on your roof. With these three ingredients, algae can spread over your entire roof, causing wood rot and other structural damage as it “eats” through your shingles.

Roof algae, Gloeocapsa Magma, looks like large black streaks on your roof. Though the algae spores themselves are a blue-green color, like you see in ponds, it looks darker on roofs.

Mold and mildew get a helping hand from the algae. With a combination of algae and water to live on, these issues can spread very fast, before you ever even know it’s there. By the time you discover exterior mold, it will likely be inside your home as well.


Mold is the result of moisture absorption and develops on interior drywall and wood areas that have poor drainage. Additionally, it can cause serious respiratory issues for your family if it is inside your home, so it is of paramount importance that you handle it quickly.

You will often find mold where your roof and exterior walls meet, as well as on the shingles themselves. It looks like black, brown, or green patches and is often slimy with a foul smell.


Mildew can also have some health effects and can certainly affect the structural integrity of your home.

Mildew is powdery and comes in a range of colors, from black to white to green or even pink! It spreads much more quickly than algae and mold and can degrade wood, causing wet rot.

Stop the spread of fungus and keep your family healthy!

Contact Tittle Brothers Construction for a free inspection and quote.