Is Moss Bad For Your Cedar Shake Roof?

Posted on: 27 April 2016


During the spring, cedar shake roofs in cool, wet climates may develop a growth of moss on their surface. This can be troubling for the homeowners. Knowing what moss can do to your roof and how to prevent moss from returning can help you maintain your property this spring.

Is moss bad for your cedar shake roof?

Yes, moss is bad for your cedar shake roof. Cedar is naturally decay resistant, however, moss will hold soil and moisture against a cedar shake roof, which can cause the wood to deteriorate over time.

If your cedar shake roof has moss growing on it, what can you do to remove the moss?

Use a long-handled soft-bristled brush to clean the moss off of the cedar shakes. For a cleaning solution, use a combination of water with a small amount of bleach mixed into it. You can use chlorine or oxygen bleach for this purpose. Keep in mind that oxygen bleach is less damaging to your landscape, if it should drip off your eaves into the shrubs and plants below.

To clean the roof, dip the brush into the water and then use it to wipe off the moss growing on the cedars. Make sure that the brush has soft bristles to avoid damaging the cedars. Always use the brush to pull down on the cedars in the direction that water flows off your roof. Pull the moss down off of the roof, then throw it into a burn pile or garbage container later. When you're finished, rinse the bleach and water off of your roof with a spray of water from a hose. Never use a power washer to remove the moss, as this may damage the shakes.

What can you do to prevent the moss from returning?

You can prevent the moss from coming back by making the conditions around your roof less favorable for moss growth. For example, overhanging trees cut back on air circulation around your roof while simultaneously throwing the roof into shade and contributing to the accumulation of moisture on the shakes. Removing overhanging branches and pruning back the trees to allow more sunlight to reach the roof will make the conditions less favorable for moss growth.

You can also prevent moss from returning by installing zinc strips at the top of the roof. The zinc reacts with water during rain storms to create a solution that deters growth of moss and algae. Have the strips installed by a roofing repair professional, like A-1 Roofing & Siding. He or she will be sure to put the strips on properly, so that the strips do no damage to the shakes.