What Is That on My Roof? Black Streaks & Algae Explained
You’ve probably seen it—those long, black streaks staining rooftops around your neighborhood. Maybe your own roof has started to show similar marks. It’s easy to assume it’s dirt or wear and tear, but the truth is more troubling: those streaks are a living, growing organism.
At TLC: Making It Easy, we specialize in safe, effective roof washing that eliminates algae, restores your roof’s appearance, and protects its lifespan. Based in Fort Wayne and serving nearby communities like Bluffton, Decatur, Van Wert, and Berne, we’ve cleaned hundreds of roofs affected by these streaks—and we know how to fix them.
Let’s break down what’s really happening on your roof, and how you can stop it before it causes bigger problems.
1. The Culprit: Gloeocapsa Magma
Those black streaks aren’t dirt—they’re caused by Gloeocapsa magma, a hardy type of blue-green algae that thrives in warm, humid climates like we experience in Indiana and Ohio.
Here’s how it works:
Gloeocapsa spores are airborne and easily spread from roof to roof.
Once they land, they feed on the limestone filler found in most modern shingles.
As they grow and multiply, they leave behind the dark streaks you see from the ground.
The longer it’s left untreated, the more the algae spreads—often across the entire roof, especially on north-facing slopes or shaded areas.
2. It’s Not Just Ugly — It’s Harmful
While the visual impact is obvious (black streaks reduce your home's curb appeal), there are more serious issues beneath the surface.
Moisture retention: Algae holds moisture against the shingles, which can lead to accelerated wear and premature aging.
Heat absorption: The dark stains cause your roof to absorb more heat, reducing your home's energy efficiency.
Shingle damage: Over time, algae degrades the shingle surface, loosening granules and shortening the roof's lifespan.
Moss and lichen growth: Algae encourages moss and lichen to grow, which can lift shingles and trap water underneath.
A dirty roof isn’t just an eyesore—it’s a threat to your home’s structure and your wallet.
3. The Right Way to Clean It: Soft Washing
Many homeowners think they can blast the stains off with a pressure washer—but this is one of the worst things you can do to a shingle roof.
High-pressure water:
Strips protective granules from shingles
Forces water beneath the surface, risking leaks
Voids manufacturer warranties
Instead, TLC uses a safe soft wash system that:
Applies a biodegradable cleaning solution that kills algae at the root
Gently rinses it away without damaging your shingles
Leaves your roof looking refreshed and new
Our team is trained in this method to ensure both effective cleaning and long-term protection.
4. How Often Should You Wash Your Roof?
Most roofs in our service area should be cleaned every 3 to 5 years, depending on:
Shade level (heavily shaded roofs grow algae faster)
Roof pitch and drainage
Local weather conditions
Nearby trees or plant matter
If you see dark streaks, moss clumps, or heavy discoloration, it’s time to act. Ignoring it only gives the algae more time to spread—and cost you more in the future.
5. Restore Your Roof Without Replacing It
One of the biggest misconceptions we hear is: “I guess it’s time for a new roof.” But in many cases, what looks like irreversible staining is actually completely cleanable.
No need to spend $8,000–$15,000 on a roof replacement.
Our average roof wash is a fraction of that cost—and the transformation is instant.
Removing algae now can extend the life of your roof by 5 years or more.
If your roof is structurally sound but looks weathered and streaky, a soft wash is likely all you need.
6. We Make It Easy and Safe
Climbing on roofs is dangerous. Letting algae sit unchecked is even worse. When you hire TLC for roof washing, you get:
A trained, uniformed technician who knows what to look for
A soft wash application customized to your roof type
Protection for landscaping, gutters, and your home’s exterior
A team that respects your property and communicates clearly
In most cases, we’re in and out in a few hours—and you get years of visual and functional benefits.
Roofs We Clean Regularly:
We service a wide range of roof types, including:
Asphalt shingles
Composite shingles
Metal roofs (where appropriate)
Garage and shed roofs
Large estate homes or small ranches
If you’re not sure whether your roof is safe to clean or how bad the streaking is, just ask us—we’ll walk you through your options.
Get Rid of the Streaks for Good
Black streaks on your roof are more than a cosmetic issue—they’re a sign your home is under attack from algae. But with the right approach, you can stop the damage, restore your roof’s look, and avoid an expensive replacement.
📅 Schedule your roof wash today and give your home a cleaner, healthier look.
📍 Serving Fort Wayne, Bluffton, Van Wert, Decatur, Berne, and surrounding areas.