As the summer sun beats down on your Stevensville home, it might be doing more harm than you realize—especially to your roof. Those black streaks or green patches you see aren’t just an eyesore. They’re often signs of algae or moss taking hold. And in the heat and humidity of summer, these roof invaders can grow fast and cause serious damage if left untreated.
Table of Contents
1. The Science Behind Algae Growth on Roofs
Roof algae, particularly Gloeocapsa magma, is a blue-green algae that thrives in warm, humid environments. What you see as black streaks are actually pigmented coatings it forms to shield itself from UV rays.
Why summer accelerates growth:
- Heat + moisture = perfect conditions.
- Roof shade traps moisture, helping algae colonize.
- Humidity creates a damp environment, especially under tree cover.
Common signs to watch for:
- Dark streaks running down roof slopes
- Green moss clumps along edges or near shaded areas
- A slight “fuzzy” texture in patches
Don’t ignore these—algae can erode shingles and lead to long-term damage.
2. What’s the Difference Between Algae, Moss, and Lichen?
While they often show up together, these organisms are different:
- Algae: Appears as black or dark green streaks, especially on asphalt shingles.
- Moss: Forms thick green patches that retain moisture and lift shingles.
- Lichen: A mix of fungus and algae that etches into shingles over time.
All three thrive in the same environment—shaded, humid, and sun-exposed roofs. And all three can damage your roof’s integrity and lifespan.
“What causes black streaks on roof shingles?”
Black streaks are typically caused by algae (Gloeocapsa magma) that feed on limestone filler in shingles and grow faster in humid, sunny conditions.
3. How the Sun Helps—and Hurts
Sunlight itself doesn’t directly cause algae, but it fuels the conditions algae love.
Here’s how summer sun plays a role:
- UV rays damage roofing materials, making them more porous.
- Hot surfaces increase condensation when followed by cooler nights.
- Partial shade from trees traps moisture—algae thrives in this hot/damp mix.
Even if you can’t see it from the ground, your roof might be quietly hosting a summer algae party. And that party can lead to shingle decay, mold, and higher energy bills.
4. Roof Cleaning Solutions That Actually Work
The best way to protect your roof this summer? A professional soft wash service from a trusted company like All Hands Pressure Washing.
Benefits of professional roof cleaning:
- Kills algae and moss at the root—not just rinses them away.
- Preserves shingle life by gently removing contaminants.
- Improves energy efficiency by removing dark streaks that trap heat.
- Enhances curb appeal instantly—hello, clean roof!
Unlike high-pressure washing, soft washing uses specialized solutions and low pressure to treat the roof safely.
5. When to Schedule Roof Cleaning in Summer
Timing your roof cleaning can make all the difference:
- Early summer: Catch growth before it spreads.
- After a stormy week: Moisture increases growth; follow with a cleaning.
- Before selling your home: A clean roof boosts value and buyer confidence.
All Hands Pressure Washing offers expert roof cleaning throughout the Eastern Shore, ensuring your roof stays in top shape all summer long.
Beat the Streaks Before They Spread
Don’t wait for algae to dig in. Call 443-973-5127, visit allhandspws.com, or check us out on Google Maps to schedule a roof cleaning today. Protect your home, enhance its beauty, and keep your roof cooler and cleaner all summer long.