How to Clean a Roof to Remove Black Algae Stains

To clean an asphalt shingle roof to remove black algae stains:

  1. Mix Cleaner: Mix up oxygen based cleaner with water in a five-gallon bucket, following the instructions.
  2. Wet Roof: Lightly wet down the roof using a garden hose.
  3. Apply Cleaner: Use a stiff bristle brush to apply the cleaner to the roof, being careful not to damage the shingles.
  4. Let Cleaner Work: Allow the cleaner to remain on for 15 minutes or so.
  5. Rinse Roof: Rinse the cleaner off with a garden hose.

Watch this video to find out more.

Further Information

Danny Lipford: Steven wants to know, “How do I clean algae off my roof?”

Even with a fairly new roof like this, it won’t be long before the dark algae stains start making it look really bad. And it’s only going to get worse as it gets older. But here’s what you can do to clean it up a little bit.

Use some oxygen-based cleaner, usually in a powder form, mix it in a five-gallon bucket with water. Make sure you check the manufacturers’ instruction on exactly how much to use. Then, lightly wet down your roof, then use a stiff bristle brush to apply the cleaner. Allow it to sit there for about 15 minutes and do the work for you, then blast it off with a garden hose. And your roof is going to look a lot better for a lot longer.

But if your roof is this steep I would recommend you rely on a professional roof cleaner who’s used to this type of situation.


  1. Left message, hoping to hear from you.
    I have an ugly gasoline stain on my shingles from a leaf blower that lost a cap when getting rid of leaves in my gutter. How do I get rid of this (not algae , that cleaner does nothing) ugly stain. Please help!! Thanks!

  2. trying to find out if algea that drains from a roof effectswater in rain barrel that is used on plants and how to make water safe for plants.


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