How to Get Rid of Moss & Lichens on the Roof

If you notice green, white or gray spots on your roof, moss and lichen are likely the culprits. Roof moss and lichen are not only unsightly but can damage the roof over time. To remove lichen and moss from the roof, try the least-toxic method for moss and lichen removal first (oxygen bleach) before moving on to a harsher method (chlorine bleach).

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Preserve your roof by removing moss and lichen promptly.

Oxygen Bleach

Step 1

Fill a bucket with 1 gallon of hot water. Add 8 ounces of oxygen bleach to the water. Wait about five minutes for the oxygen bleach to completely dissolve into the water.

Step 2

Pour the mixture into a garden sprayer. Mix the solution directly into the sprayer rather than the bucket if you have a garden sprayer able to hold the full gallon of water.

Step 3

Wet down the roof with plain water from the garden hose. Spray a generous coating of the oxygen bleach mixture onto the roof immediately.

Step 4

Allow the oxygen bleach to sit on the roof for about 20 minutes. Spray more of the solution onto the roof if it is hot or sunny outside and the mixture is drying onto the roof before the 20 minutes has elapsed. The goal is to keep the roof wet with the oxygen bleach mixture for at least 20 minutes.

Step 5

Use a long-handled scrub brush to scrub the moss and lichen spots. It will help to loosen them up before rinsing.

Step 6

Rinse the roof with plain water. Work from the peak of the room down.

Step 7

Repeat the application of oxygen bleach, if necessary.

Chlorine Bleach

Step 1

Fill a bucket with 1 gallon hot water. Add 1 cup chlorine bleach, 1 cup liquid laundry detergent and ¼ cup trisodium phosphate.

Step 2

Pour the mixture into a garden sprayer. Mix the solution directly into the sprayer rather than the bucket if you have a garden sprayer able to hold the full gallon of water.

Step 3

Spray a generous coating of the cleaning solution onto the roof. Scrub the moss and lichen from the roof with a long-handled scrub brush.

Step 4

Allow the bleach solution to remain on the roof for 10 to 15 minutes. Do not let the bleach solution remain on the roof any longer than 15 minutes; chlorine bleach can cause damage to the roof if left on any longer.

Step 5

Rinse the solution from the roof with plain water from the garden hose. Rinse from the peak of the roof down. Reapply the solution, if necessary.