How to Remove Algae and Moss From the Roof

Wooden shingle roof with molds and algaes on the surface

Are you tired of getting rid of roof and algae moss only to see the problem come back a few weeks later? This guide will help you learn about the causes, remedies, and prevention of algae and moss.

Why do algae and moss grow on the roof?

Salt Lake City residents who have had professional residential roofing services in the past may have an idea why algae and moss grow on the roof. But if you don’t, these are the things you should know.

  • The common types of algae are gloeocapsa magma and blue-green algae
  • Moss consumes water through its leaves instead of the roots
  • Algae and moss spread via spores transferred by the wind or animals
  • Algae and moss thrive in rooftops that are damp and exposed to limited sunlight
  • Both organisms have detrimental effects on the roof material

If left untreated, moss and algae eat through virtually any roofing material, shortening your roof’s service life dramatically. Aside from that, the damage can cause water to leak into your house, which will ultimately lead to other structural problems.

How to remove moss and algae from the roof

Here is a quick tutorial on how to fix algae or moss problem:

Step 1: Prepare the materials needed:



Safety goggles

Safety rope

Scrub brush

DIY or store cleanser

Hose with a spray nozzle

Step 2: Hose off moss and algae

After you make sure that you won’t slip while working on the roof, use your garden hose to spray off the moss and algae growths. Use your scrub brush to remove stubborn growths, one area at a time.

Step 3: Douse the roof with moss and algae cleaning solution

If the growths do not relent after hosing and brushing, pour a cleaning solution on your shingles. A DIY cleanser consists of 1 part water and 1 part laundry bleach. For store-bought cleaners, follow the instructions on the packaging.

Leave the cleanser on for 30-45 minutes. Don’t let it dry completely. Then scrub the area to remove the growths before rinsing with water.

How to prevent moss and algae from growing on the roof

Roof and gutter cleaning with high pressure

Once you remove the algae and moss from the roof, you should be okay, at least for a few weeks. To prevent growths from coming back, install strips of copper and zinc sheet metal below the top ridge on the roof’s either side. Whenever it rains, the copper and zinc molecules will pour down the roof and kill the spores.

Alternatively, you can buy commercial products that get rid of growths and keep them away for a certain period. Some products’ effectiveness lasts up to a year, so you would need to reapply it periodically.

As a final note, here are the things that you should not do when getting rid of moss and algae:

  • Using a pressure washer
  • Scraping the growths
  • Spraying water at an upward angle
  • Using overly acidic cleaners

There you have it; a pretty simple solution that you can even DIY. However, if you don’t feel comfortable working on the roof or don’t have the safety gear to do it, hire a professional to do it for you.

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