Home Improvement Expert Danny Lipford

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How to Remove Moss from a Roof

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Green moss growing on roof.

What causes moss to grow on a roof and what’s the best way to get rid of it? -B.V.

Moss thrives in a damp, shady environment. For this reason it often occurs on the north side of a roof—since it receives the least amount of sun—or under overhanging trees that provide shade. Over time it can cause roofing to degrade.

You can physically remove moss from your roof with a long handled scrub brush if you’re careful not to overdo it. While a pressure washer can be used, the powerful jet of water could damage asphalt shingles. With either method, work down the roof to keep from lifting and breaking shingles.

There are also several chemicals on the market specifically made to kill moss. Diluted bleach will work as well, though the runoff can damage plants. Be sure to wear rubber gloves, protective clothing, and eye protection when working with chemicals.

To prevent moss from returning, cut back any limbs that overhang the roof, or install strips of copper or zinc along the ridge. Since the treatment for moss is similar to that for algae stains, refer to our article on How to Remove and Prevent Algae Stains on Asphalt Shingle Roofs for more details.

Danny



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18 Comments on “How to Remove Moss from a Roof”

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  1. Larry Says:
    April 22nd, 2012 at 3:01 pm

    I have a black asphalt roof and have moss starting to grow on it and I have removed the tree causing the issue. I am concerned about using bleach on a black roof. What are my options or am I over reacting about using bleach?

  2. Linda Epstein Says:
    June 21st, 2012 at 9:31 am

    I was told by our roofing supply co. NOT to use bleach because it would discolor our dark charcoal shingles. They recommended a number of solutions containing copper sulfate (which is plant friendly) and/or zinc (which they do not sell), as well as the ridge strips for prevention. Can you give me any formula or recommendation without bleach?
    Thank You

  3. Kirk Warner Says:
    August 27th, 2013 at 2:15 pm

    Using bleach is recommended by most shingle roof manufactures and the ARMA, (Asphalt Roofing Manufactures Association).

    ARMA statement:
    “The most effective method of cleaning algae and moss from a roof is with a 50:50 mix of laundry strength liquid chlorine bleach and water. Apply w ith a sprayer and allow the solution to dwell on the roof surface for 15 to 20 minutes, and then rinse thoroughly with low pressure water”.

  4. James Kille Sr Says:
    May 16th, 2014 at 7:57 pm

    Hello I have some moss and some black streaks, if the only thing I did is put installed copper strips on both sides of the roof cap, over time would that be enough to remove the existing moss and blacks strikes?

  5. Official Comment:

    Ben Erickson Says:
    May 17th, 2014 at 7:35 am

    James,
    It should, but it would take a while. If you want to see quicker results, consider sprayer an algae and moss killer, like Wet & Forget, on the roof when you install the copper strips; or clean the roof using a TSP and bleach mix. Check out our article on How to Remove Black Algae Stains on Roofs to find out more.

  6. Eric Antilla Says:
    October 11th, 2014 at 6:57 pm

    can i use diesel oil sprayed on asphalt shingles

  7. Deb Says:
    October 18th, 2014 at 4:02 pm

    Eric why in the world would you want to use diesel fuel which would be toxic to the environment not to mention flammable? Haven’t you seen what oil spills do? Please do not use any kind of oil or gas.

  8. john b Says:
    January 24th, 2015 at 6:01 am

    I have been aware of the copper strip solution for a long while but never dared do it for fear of attracting a lightning strike does the strip be fixed continuous or with breaks

  9. Official Comment:

    Ben Erickson Says:
    January 24th, 2015 at 8:25 am

    John,
    While metal, such as copper or zinc, conducts electricity, it doesn’t attract lightning, and installing a strip of metal near the peak of your roof to kill algae shouldn’t cause a problem if lightning should strike. If it did, metal roofs wouldn’t be allowed.

  10. Sandra Says:
    March 9th, 2015 at 8:45 pm

    What is the best way to remove moss of Terracotta Roof Shingles?

  11. H Says:
    March 23rd, 2015 at 3:20 pm

    I have a flat roof with moss on it amongst the peddles that were there to protect the roof. Can I pick it off or would you recommend treating it with a bleach

  12. Michael Bednar Says:
    May 6th, 2015 at 7:39 pm

    Hello. We had a contractor install the zinc strips and it did not prevent the growth of lichen or moss. The cost was well over $500 and we are unhappy with the results.

  13. arnold Says:
    July 7th, 2015 at 9:27 pm

    When should one apply the bleach solution? After a rain, early morning, or evening?

  14. jean Says:
    July 12th, 2015 at 1:34 pm

    I have killed all the moss on my roof, but it leaves these crusty clumps of dead moss. I am scraping them off with a plastic tent spike. Am I damaging the shingles? They will not sweep off. Any suggestions???

  15. Dennis Says:
    July 15th, 2015 at 3:56 pm

    For removing moss clumps, a retired roofer in my church recommended using a garden rake!

    Turn the tines UP so you don’t damage shingles, work from the peak down so you don’t lift shingles. The rounded back bar on the rake rides easily down the shingles but knocks the moss loose.

  16. Bruce Says:
    July 29th, 2015 at 5:39 pm

    Thanks for the suggestion to use the back side of a lawn rake. Worked great. Followed up with a rounded stick (piece of a cedar shake so soft wood and thin). Then swept with a nylon bristle (softer than straw) house broom. Was easier than I thought it was going to be, but still work of course. Thanks again. B

  17. Dogcliff Says:
    August 8th, 2015 at 1:44 am

    Great advice all! So where do you get copper/ zinc strips? How large? What size? I’m going to attack my roof next week using bleach solution with fingers crossed…

    dc

  18. Don S Says:
    August 27th, 2015 at 3:34 pm

    I mixed a strong solution of ferric sulfate crystals (moss out for lawns) and hot water and a few drops of liquid soap. I let it cool so it precipitated out, then mixing the remaining solution half and half with water and sprayed it on my composite roof/moss. Seems to work for small patches- but will it damage composite??

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