Remove Algae From A Shingle Roof And Prevent It From Forming Again

Black streaks on your home's shingle roof are a sign that algae has formed. Algae often appears in humid climates and can cause shingles to deteriorate if it is not removed. Learn how to eliminate algae with the following steps. Once the roof is restored to its original condition, you can prevent new algae from forming by installing a zinc strip across the top of the roof.


  • ladder
  • broom
  • water hose
  • garden sprayer
  • bleach 
  • detergent
  • water
  • plastic sheeting
  • scrub bush
  • zinc strip
  • measuring tape
  • roofing nails
  • nail gun

Clean The Roof And Remove The Algae

Place a few pieces of plastic sheeting over flowers, grass, and shrubs that are located close to the house. The plastic sheeting will keep plants protected from the cleaning solution as it drips off the roof. Set up a ladder near the end of the house. Remove large pieces of debris from the roof with a broom. Use a water hose to remove dirt from the shingles. Add equal parts of water, heavy duty detergent, and bleach to a garden sprayer's tank. Spray the mixture on all of the black streaks on the roof.

Allow the cleaning solution to penetrate for several minutes. Move a long-handled scrub brush back and forth over the stains. Push down firmly on the scrub brush's handle as you are completing this step. Use a water hose to rinse away the cleaning solution, once all of the algae has been eliminated. Remove the plastic sheeting that is covering the plants. 

Protect The Shingles From Damage

Installing a zinc strip across the top of the roof will prevent algae from forming again. Measure the length of the roof so that you purchase a zinc strip that is long enough. Place the strip across the bottom of the top row of shingles, inserting the top of the strip underneath the bottom of each shingle that runs across the roof. Secure the zinc strip by installing roofing nails through the middle of it, spacing them out evenly all the way across the roof.

Whenever it rains, zinc from the strip will roll down the roof. Zinc will prevent algae from forming on the shingles and will also stop moss, fungus, and mold from forming. The zinc strip that you have installed will last for several years. Your home will look much nicer with a stain-free roof, and you will not have to worry about roofing materials becoming damaged any longer. 

For more information, visit or a similar website.