Remove Mildew Streaks From Asphalt Shingles On Your Company’s Rooftop

Grey or green mildew streaks that are on the surface of some of the asphalt shingles on your company's rooftop can diminish the beauty of the building and give your business an unprofessional appearance. Learn how to remove these unsightly stains with the followings steps. Once the shingles are clean, protect them from additional staining.   


  • garden sprayer
  • industrial-strength detergent
  • water hose
  • stiff-bristled scrub brush
  • ladder
  • bleach
  • tarps
  • measurements for rooftop
  • zinc strip
  • nails
  • hammer

Remove The Mildew Stains

Prepare a solution that is half water and half industrial-strength detergent and fill a garden sprayer's tank with it. Mix the cleaning solution until it is sudsy. Set up a ladder near the roof and make sure that it is sturdy before climbing it with the garden sprayer and a scrub brush. If possible, have someone spot you while you are on the ladder.

Spray a generous amount of the cleaning solution on each stain. Wait for the soapy water to penetrate each shingle's surface for a few minutes before moving the scrub brush over them. Press down firmly on the brush's handle as you move it back and forth over each stain. Rinse the rooftop off with water when you are done. 

Add Bleach For Severe Stains

If any of the stains aren't responding to the soapy water, add a small amount of bleach to the cleaning solution. Protect the property that is next to the building with tarps so that grass or plants are not exposed to any chemicals. Spray the stains with the upgraded cleaning solution. After several minutes, scrub the stains. Rinse the roof off once all signs of mildew have been eliminated.

Protect The Roof From Mildew

A zinc strip can be installed across the top of the roof and will protect the shingles from mildew stains in the future. This material will also protect the shingles from moss growth or mold. Purchase a strip that is the same width as the rooftop. Place the strip underneath the bottom of each shingle that is at the top of the roof. Lift the shingles up slightly and wedge the top of the strip under them. Insert nails throughout the strip to hold it in place.

Each time that it rains, zinc will drip down all of the shingles and create a protective layer that will prevent stains from forming. Your company's rooftop will stay clean regularly and will continue to enhance and protect the building that it is covering.