Don’t worry, those black streaks on your roof aren’t mold.  It’s an algae called Gloeocapsa Magma. The algae is actually blue-green, but as it grows, it hardens and turns to black stains.

Here’s what you need to know about black stains on your roof and how to get rid of them.

  • The roof-invaders love an environment with moisture, with dew and shade.
  • The algae feeds on the limestone in the shingles.
  • The algae travels by air.  One neighbor can have a few spores and spread it to the entire neighborhood.
  • The algae mostly just makes your roof look bad, but it can prematurely age the shingles over time.
  • Don’t use a high-pressure washing system to get rid of the algae because it can damage the shingles.  Instead, gently spray a solution of bleach, trisodium phosphate, and water on a cloudy day.  Rise with a soft-pressure wash after about 20 minutes.
  • Install zinc or copper strips along the top course of shingles to prevent algae, moss and fungus from growing.

The experts at J. Adams Roofing can help you get rid of those pesky black streaks! Call us today to schedule your FREE roofing consultation!

Sources:; Black Roof Stains, Check for Algae

The Family Handyman;  Prevent Black Streaks on Roof