Part of good roof maintenance is keeping your roof clean. That involves removing any moss or algae that has begun to grow on your shingles. In addition to looking unsightly, moss and algae can be a serious problem if left untended.

What are Moss and Algae?

Moss is a green, leafy plant that has no root system. It needs a moist, humid, shady area to grow and enjoys growing on hard surfaces – like your roof. Algae is another type of plant that also grows in moist, shady areas like your roof. It may appear as black streaks on your shingles that you may mistake for mold. In actuality, this is a blue green algae that grows in the same place.

Moss on Roof: Why Do Moss and Algae Grow On Roofs?

Moss and algae tend to grow on roofs that have a lot of shade or don’t get a lot of direct sun. These roofs tend to be cooler and stay damp longer than roofs with full sun, which helps encourage moss and algae growth. Unfortunately, over time the moss and algae on your roof can start to encourage more moisture, as well as a break down and decay of your shingles. This shortens the lifespan of your roof and can lead to leaks and water infiltration down the road. Thick layers of moss can also begin to lift up the shingles from your roof, which allows water to enter by seeping beneath them. Moss and algae can both also detract from your home’s curb appeal, which in turn could make it more difficult to sell.

Roof Maintenance: Roof Moss Removal

When you notice the signs that moss or algae is beginning to grow on your roof, you need to take steps to remove it – and to prevent it from coming back. Remember that leaving it alone is merely going to shorten your roof’s lifespan and encourage problems down the road. Roof maintenance is very important.

Remove Its Shade

Moss and algae prefer to grow in shade, so your first step should be trimming back any trees that are blocking the sun from reaching your roof. This will help prevent new moss from taking hold.

Clean Your Roof

While you may be tempted to get out the pressure washer and blast the moss or algae off your roof, this can lead to further damage of your shingles by removing the granules from their surface. Instead, the most effective way to remove the moss or algae is to use a homemade mixture, a garden sprayer, and a scrub brush.

Materials

  • Water

  • Bleach

  • Garden sprayer

  • Long-handled scrub brush

Instructions

  1. Mix equal parts water and bleach in the container of your garden sprayer.

  2. Use this mixture to saturate the areas of your roof that are covered with moss or algae.

  3. Let the mixture penetrate for a few minutes, and then begin agitating the shingles with a scrubber.

  4. Keep the roof wet as you scrub; if you notice the shingles beginning to dry, apply more of the bleach and water mixture.

  5. Continue spraying and scrubbing until you have removed all the moss and algae from your roof.

Keep Your Roof Clean

Moss and algae removal from your roof should be done as soon as it is noticed. When you make your annual roof inspection, be sure to take note if anything is beginning to take hold and grow, and be sure to add roof cleaning to your annual maintenance to help keep your roof in great shape.