Cleaning Moss And Algae From Your Roof And Keeping It From Coming Back

by Derrick Gordon

Your house is in a shady area which keeps it nice and cool in summer. The problem is that your roof may be the ideal place for moss and algae to grow. Here is how to clean your roof and keep these plants from taking root and damaging the shingles.

Cleaning Existing Moss and Algae from Your Roof

According to the International Association of Certified Home Inspectors, you should get around 20 years from your asphalt roof. This is true only if you take the time to keep the moss and algae off of the roof. Cleaning your roof is an annual project, and if you're uncomfortable working on a wet, slippery roof, contact a local roofing contractor to do the work. if you want to tackle this project yourself, here are the steps to get your roof clean again.

  1. Sweep off any debris from the roof. Sticks, leaves, branches and especially pine needles provide a barrier that holds water, creating a place for moss and algae to grow.
  2. Mix equal parts of chlorine bleach and water and spray it on your roof. Start at the peak of the roof and work your way down. This will kill the moss and algae, especially in the tiny cracks in and between asphalt shingles. If the runoff from the roof will drip onto any plants in your yard, hose down the plants first to protect them from the chlorine solution.
  3. Let the solution sit on the roof for a couple of hours, then rinse it off. Your garden hose will work well enough and is safer to use on the shingles than a power washer. Wash the roof off from the peak down, focusing on the spaces in and between the shingles.
  4. Clean out your gutters and downspouts so water doesn't back up and touch the edge of the roof. Wet shingles at the edge are a prime place for algae and moss to grow.
  5. Replace any damaged or cracked shingles. Hammer any shingles down that have been loosened by the wind. Check underneath any damaged shingles for signs of algae and moss, and spot treat those areas with your chlorine solution again.
  6. Check around the edges of metal flashing around vents, skylights and chimney or flue pipes. If water can get under a loose edge, algae and moss can start growing. Hammer down loose flashing and seal the edge against the roof with an asphalt sealer.

Keeping Moss and Algae from Growing on Your Roof

Once the roof is clean, here are a few ways to prevent your roof from becoming a mossy, algae-covered mess.

  • Talk with a local roofing company about a roof coating. This is a chemical, usually containing zinc and copper, that is sprayed on the roof. Moss and algae won't grow on the roof when these elements are present.
  • Purchase strips of zinc or copper flashing and slide them under the first row of shingles up by the peak. When it rains, the zinc or copper will wash down over the roof, making it uninhabitable for moss and algae.
  • Trim any trees overhanging the roof. As long as you have tree branches over the roof, you'll likely have to deal with moss and algae because of the debris they constantly drop on the roof.

Spend a little time each year on your roof, or have a professional roofing company, like Sunik Roofing, come out and maintain it. The time you spend will translate in a longer life for your roof.