How It Works

Select the work to be done
Let us know what project you need help with and when you need it done - we'll match you with the right pros for the job.
Compare matched pros
Verify pro credentials, read reviews, ask questions, discuss availability, and request project estimates.
Complete your project
Hire the pro that's right for you and your budget. After the project is complete, let your community know how it went.
Powered by

The Home Depot

Why Do I Have Roof Moss?

Pro Referral > Home Guides > Roofing > Why Do I Have Roof Moss?
Why Do I Have Roof Moss?

If weather conditions are damp and your roof has significant shade over it, you may notice moss creeping over your roofing materials. Different types of moss can appear and spread on a roof, depending on your geographic location.


Although unsightly, you can tackle moss on your roof in several different ways. Once you have the background information about why moss appears on a roof, you’ll be ready to remedy the situation effectively.

  1. 1.Conditions for Moss

    For moss to develop, it needs three conditions – shade, temperatures between 32 degrees Fahrenheit and 70 degrees Fahrenheit and moisture.

    Perhaps you’ve heard the old wives’ tale about moss growing on the north side of structures and trees. If you have a roof with moss growing on it, you’ll know that this isn’t necessarily true. In fact, moss will grow anywhere on virtually any outdoor surface or structure. Common surfaces for moss growth include wood, asphalt, metal and glass. Moss grows without roots, so it does not require soil.


    For moss to develop, it needs three conditions – shade, temperatures between 32 degrees Fahrenheit and 70 degrees Fahrenheit and moisture. If temperatures rise above 70 degrees, you may notice the moss becoming dormant, but it will not die. With water running down the pitch of a roof, moss has the ideal environment to grow.

  2. 2.Removal Methods

    If you notice moss developing on your roof, you have several options for removal. It may be possible to scrape away excess moss with a long-handled brush. Once you remove the largest pieces of moss, wash the roof. Some experts recommend a power washer and others recommend avoiding a power washer because of the potential for damage to the roofing materials.


    Use a heavy-duty blower to blow away moss from the roof surfaces. This removal method can be especially effective for dried moss. Use this removal method on a dry day for best results.


    Try commercial moss removal products to remove moss. Zinc sulfate is effective for removing moss from outdoor surfaces. By spraying moss-removal chemicals onto the moss on your roof, the moss will dry up and die. The dead moss will remain on your roof, however, so after the moss dries up, you must scrape or wash it off.


    Use care when working with zinc sulfate because there are health issues associated with it. Zinc sulfate may irritate eyes and it may have a connection with miscarriage. Zinc sulfate also causes damage to aquatic life, including fish.

  4. 3.Prevention Methods

    To prevent moss from marring your roofing materials, keep your roof free of leaves and branches. When these organic materials build up on the surface of your roof, the moisture associated with the materials could lead to moss growth.


    Trim trees to allow as much sun to reach your roof as possible. With strong and direct sunlight on the roof surface, moss growth will not be as abundant as it would in shady environments.


    Depending on the amount of moss on your roof and the type of roof structure you have on your home, you may be able to treat moss issues yourself. Visit the Pro Referral website for information about roof maintenance for additional help.

Find Pros

Get your home project started today with help from Pro Referral’s qualified network of pre-screened and background-checked professionals available in your neighborhood.

Get Expert Advice

Submit your toughest home improvement questions to our knowledgeable experts and receive free personalized solutions, product recommendations, how-to advice, and more–all within 48 hours or less.