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How to Clean off Roof Stains

Kate Evelyn

Roof stains, which are often black or green, are usually caused by mildew growing on the shingles. Bird droppings can also soak into shingles and discolor them. Luckily, you can remove both types of stains with one method and you won’t have to replace your roof just because it is unsightly.

Pick a day to do your cleaning when it is not too hot or rainy. This will make the experience a lot more bearable for you.


  1. Put your sheets of plastic on top of plants near the edges of your home so the cleaning solution doesn’t drip on them. Also remove any pet toys or children’s toys that are less than 6 feet out from house. If you have leaves or other large pieces of debris on the roof, lean your ladder against the rain gutter, make sure it is firmly planted, climb up and have an assistant hand you a push broom. Use the broom to push these items off so they don’t get in the way of your cleaning the stains.

  2. Open your garden sprayer and pour in a cup of chlorine bleach. Add a cup of powdered laundry soap. Then add a gallon of water with the hose. Close the sprayer tightly and swirl it around to mix the cleaning agents with the water. Ten times should be enough. It doesn’t have to be perfect.

  3. Push the pump handle of the sprayer in and out several times to give it some air pressure. When you feel it is pumped adequately, climb the ladder and have your assistant hand you the sprayer. Start spraying at the top left and move to the right, continuing down the roof in rows. Make sure to saturate all of the stains.

  4. Let the bleach solution dry for 20 minutes. Then take the garden hose up the ladder with you and have your assistant turn it on full blast. Rinse the roof from top to bottom, making sure not to splash any bleach solution in your face when you’re working on the bottom part near the gutters.

  5. Check to see that all the stains are gone. If not, try brushing them with the push broom and then rinsing again. If that doesn’t work, repeat Steps 2 through 4. As a last resort, empty out your sprayer and fill it with a half-gallon of water and a quarter cup copper sulfate. Apply this to the roof and do not rinse it off until your mildew stains change from green or black to brown.

  6. Tip

    Copper sulfate is sold at garden centers.


    Don’t try to complete this task yourself. You need someone to help you for safety reasons.

    Put on goggles and long rubber gloves before you start to protect yourself from the bleach.