Have You Ever Had Your Roof Cleaned?

Have you ever had the roof of your home cleaned? In November 2019, I shared this photo of my home shortly after adding wreaths to the windows for the holiday season. When I took that photo, I think that was the first time I had noticed some blackish streaks on the roof.

How to Hang Christmas Wreaths on Exterior Windows

 

I figured the streaks were some type of staining caused by the trees that surround my home and I wondered if there was a way to clean a roof. I contacted the company that had installed my roof 12 years before to ask if a roof could be cleaned and who they would recommend. They gave me the name of a company/guy and I contacted him for an estimate.

I ended up not getting my roof cleaned because the estimate was very high, over $700. Plus, I didn’t feel comfortable with the guy who came out. I just didn’t have the best feeling about him, didn’t fully trust the process as he explained it. I’ve been through a lot of home renovations over the years and I’ve learned to trust my gut instinct about people, so I decided I’d get more estimates later on after the holidays.

How to Hang Christmas Wreaths on Exterior Windows

 

Then 2020 happened and I forgot about the roof. I wasn’t here much of 2020 since I was in Ohio helping with my grandsons who were being homeschooled since the schools were closed and later only open for half days.

A few days ago I shared this photo of the hydrangea I have near the mailbox. I noticed the roof once again, the streaking was really bothering me! Funny I only notice these things in photos. I guess when I’m outside, my focus is normally on something else.

After a BNOTP reader nicely asked about it in an email, I decided to check into the whole roof cleaning thing again. I called a company I found online that had a ton of 5-star reviews and got another estimate for having it cleaned. This estimate was a bit better, coming in at $635. I think I’m going to get one more estimate from another company with great reviews, just so I’ll have one more for comparison.

 

The company who recently gave me an estimate mentioned that sometimes the roof manufacturer will pay for the cleaning if it falls under their warranty. I pulled out my paperwork from when I had my roof replaced and found that my roof shingles were manufactured by Owens Corning. At the time my roof was installed 14 years ago, the warranty against streaking/black marks, which is really just algae from rain/humidity, is 10 years. I first noticed the streaking happening around two years ago, which would have been around the 12-year mark.

 

Apparently, how fast the streaking occurs depends on the area/weather where you live. We get a fair amount of rain and Georgia is definitely a humid place. This chart I found online HERE shows where the streaking/algae growth on roofs most commonly occurs.

 

One very important thing I learned during my conversation with Owens Corning is this: when having a roof cleaned, the representative for Owens Corning said the cleaning company should not use more than a 50/50 ratio of bleach to water, or it would void my warranty. I checked and the company I’ve been talking with uses a 20/80 ratio of bleach to water, so well below the ratio that could void the warranty.

Also, you never want to let anyone pressure wash your roof. Pressure washing could seriously damage a roof. Instead, roof cleaning companies “soft-wash” the roof. It’s my understanding they spray the cleaning solution on the roof, wait a bit, then rinse it off. The company I talked with never even gets on the roof at all.

 

Other than the streaking/algae not looking nice, the other reason I’ve read that it’s good to have the black streaking/algae removed from a roof is if it’s left on a roof for too long, the algae could eventually shorten the life of a roof since it tends to hold moisture to the roof shingles.

I asked Owens Corning why the streaking didn’t occur at all for the first 10-12 years after it was installed. The representative said that the shingles are manufactured with copper in them which prevents the growth of algae for at least 10 years. I wish they could make it where it would prevent it for the life of the roof, not just 10 years.

My roof cleaning is scheduled for later this month. I’ll be sure to share an “After” photo once it’s done. I’m still going to get one more estimate–just to make sure the price I’ve been quoted is fair. It probably is, but I feel better getting one more estimate.

Have you ever had your roof cleaned? Was it expensive? How did the process go? How long did your roof stay clean afterward? I would love to hear about your experience!

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Comments

  1. Our Home Owners Association requires roof cleaning if they see it needs it. Otherwise you get a fine. I’m not sure what we pay. We just got a new roof so hopefully it won’t need anything for awhile.

  2. I’ve never had roof cleaning done but I have been curious about it. I wondered how they did it without disturbing the granules on the shingles. I see better now from your explanation how it is done so as to avoid this…I just assumed they were up on the roof blasting away. Ha! Please keep us posted as I would like to know how your experience with this goes. Thanks…your posts are always so informative!

  3. I live in the severe area on the map and have experienced black streaks on the shingles. We had hail damage a few years ago and insurance paid to replace the entire roof. Our contractor recommended adding a strip of copper along the ridge cap to prevent streaking again. So far so good!

    • Oh, that’s good to know! I wonder how that helps protect the rest of the roof?
      Thanks, Hallie!

      • Adding a strip of copper is a great idea for areas prone to moss or black streaks on shingles. The way I understand it is every time it rains, the copper “dissolves” a tiny bit into the rain water and washes down the entire roof killing any growth. It has worked great for my father in law who always had moss on his shady roof. The copper strip only gets replaced when the shingles need replacing.

  4. I will be interested to see how this goes – Hoping you will take pictures of the process – I’m interested in seeing how will they spray the roof without getting onto it. Do they include other areas like the gutters or soffits?
    What did the company say about protecting the painted areas on the house (like siding, trim, shutters, etc.) and landscaping when using a 20% bleach solution? Do they guarantee that the spray/run-off won’t cause any streaking or foliage damage? Or, do they rinse the house and landscaping to keep streaking or damage to a minimum? Love your blog!

    • Thanks, Amma! I will def try to get some pictures. I asked about the plants and he said they spray them down/rinse them off with water before and afterwards. I asked about covering them and he said they don’t do that because it can cause damage to the plants. When I’ve had my house pressured washed, they wash the gutters and so far I’ve never had any issues with the plants, and the solution they use to pressure wash a house probably has a lot of chlorine in it…at least it smells like it does when they are doing it.

  5. Brenda S Lawrence says

    My roof looks the same way Susan, probably a bit worse in some areas. But…my roof is 30 years old and it only has gotten this way in the last 12 to 15 years. So I will soon need to replace my roof, so not going to worry about getting it cleaned. Yours is much newer. Glad they don’t get on your roof to clean it and I’m happy to hear they don’t use a power washer on it. Power washers are way to powerful for roof use. My brother is a roofer and he says the main thing is to stay off the roof, that isn’t good for it. I never knew that! lol I’m anxious to see how it goes with your roof cleaning. Hugs, Brenda

    • I always wondered about that…if walking on it damages it. I figured it wasn’t good for it. Wish they would come out with a roof that didn’t do this for the full life of the roof.

  6. We had a roof cleaned but it was a long time ago at a previous home and I don’t remember the cost. I remember seeing the Christmastime photo of your home and thinking that it would be a good idea to have your roof cleaned but didn’t think to mention it. I think it is great that you are getting several estimates. Hoping you are happy with whom you select and that your roof looks new again!

  7. You may want to ask about protection for plants close to the house. They cleaned our rooms around our condo complex and ended up killing a number of plants that were closer to the building.

    • He said they rinse off the plants before and after, but I’m still a bit worried a about them. They have a lot of great Google reviews so I guess they must be handling the plant issue okay.

  8. Sharyn Kimbrough says

    Susan, very interesting article. Thank you for all the research you do.

  9. Sandy Endle says

    All of the homes in my neighborhood have this same issue. But only the roof that faces North?!

    • My home faces north, too. I can’t really see the roof in back so not sure how it looks. I think the sun shining down def helpfs slow/prevent this issue so I guess that’s why south-facing homes don’t have as much of a problem…well, at least on the southern side part that you can see from the road. The back of the houses that face south, may have this issue on the back side of the house.

  10. Living in a condo, this wouldn’t apply to me but I still find it interesting. Such good info for those unaware of this maintenance task (me) and would not know where to start (double me!).

  11. Yes, we live in TN and had similar looking black streaks. We researched having the roof cleaned using a similar process, although the details escape me now as it was so long ago. My understanding was that leaving the black marks on would compromise the length of time the roof would last as it was some sort mildew. We have had no black marks since and are very pleased that we went ahead with the process. I think it was about nine or ten years ago.

    • That’s what I read, too–that it shortens the life of the roof. I hate spending the $$$ but def don’t want to have roof problems so it’s just one of those things we have to do, I guess. Always something with houses!

  12. Having lived in the Pacific Northwest all our lives, we have had to deal with this issue due to how much rain we get. Our first roof was light gray and showed the algae really bad. We learned with the next roof to get a black roof. Still looks new after 18 years and the algae won’t ever show. I will never have another color roof again.

  13. Nancy Brantley says

    I’m interested in seeing how roof looks after cleaning. Also, what are the name of shrubs around your sidewalk? I want to do the same look but I want them small and not have to always cut alot back….

    • The ones that are across the front of the house? Those are Carissa Hollies. They had gotten HUGE and I had them pretty drastically pruned back a few years ago. They have grown back super fast! I wish they would stay around the size they are now.

  14. Yes a roof needs to be cleaned. Algae and moss weakens it and many large homeowner companies will drop an insured upon inspection if they find it.
    I just had mine done at a comparable price. They did the shed as well.
    Turned out great.

  15. Thank you for the helpful information. I just had a new roof installed last year and will file this information away with my roof warranty.

  16. Susan, I haven’t had it done but a neighbor had just the front of his roof done, (as the back didn’t need it) and wow! What a difference it made. It honestly looked like a new roof when it was done.

    As for the price you got, I’m guessing that’s for your entire roof? You may not need the entire roof done and if they only had to do the front half, that could save you quite a bit of money. I had my neighbors guy give me an estimate for my roof, and it was higher than the one you got, but my roof is one of those complicated roofs with lots of angles and a very high pitch. Also, the estimate was for the entire roof, so if I were to be able to halve it, it would be under $500. I know that different markets have different demands and prices, but the price you were given does seem a little high to me. However, if you can just get someone out there to actually DO the work, you’ll be doing well, lol. Good luck and can’t wait to see the results.

  17. We live in Florida & have a tile roof so that is different however it might be worth mentioning that we have our roof sprayed annually with a milguard product. The roof was cleaned 11 years ago & only gets the milguard now. That keeps the roof clean & costs about $200 for a 3000 sq ft house. Maybe that wouldn’t be appropriate for a shingle roof but thought I would mention it.

  18. Learn something new every day! I had no idea. Maybe it is because it wasn’t needed with my folk’s house. My husband and I .moved lot with the military so never long enough when we owned a house to need that type of maintenance. Thanks for this lesson in home maintenance!

  19. Susan, I am farther south, but here they don’t advice to clean the roof as it damages the shingles. I would have a roofer inspect your roof. My roof is black from mildew and having a lot of trees.

    • Myrna, I was just reading on the Owens Corning website here: https://www.owenscorning.com/en-us/roofing/tools/why-are-there-dark-streaks-on-my-roof They say on that page that algae doesn’t damage the shingles, that it’s just unsightly to a lot of people. So it sounds like you’re right about it not damaging the shingles. I wonder why there are so many articles online saying that it does because it holds moisture to the shingles, when the Owen Corning website says the opposite. They explain how to remove it safely on their website. I don’t think what the cleaner will do will hurt it since he just sprays a fairly week solution of bleach up there, then rinses it off.
      I wish now I had gone with a black roof so it wouldn’t be visible or at least, not as visible. I purposely chose the gray roof thinking it would be less hot than a black roof.

  20. Catalynn says

    We have #1 grade cedar shake roof and get it cleaned every year otherwise it can have problems and it won’t last for the full 30 yrs our neighbour just had his roof replaced and installed a steel roof, were kind of wishing that we would have gone with steel, it looks amazing and it’s good for 99 years so it would easily outlast us And it doesn’t require the constant cleaning.

  21. Taria Wilson says

    I live in CA and never heard of this happening here. I do listen to the Gary Sullivan radio show and he likes a product called wet and forget. You might check Gary out and also the wet and forget page. Your home is so beautiful.

  22. SharonFromMichigan says

    I’ve seen a couple of roofs that have streaks on them in our neighborhood. I never thought there was anything that could be done. Our roof has never had streaks. Ours is in the full sun all day. Maybe that helps to keep the roof dry? I’d love to know how your roof cleaning turns out. You’re lucky to be able to get a couple estimates as a lot of places are backed up due to Covid (or at least that’s the excuse they give :))

  23. I’ve just been looking into algae on roofs and found this article from Bob Vila (used to host This Old House TV show) very helpful regarding a soft wash on a cloudy day and copper or zinc strips on the ridge: https://www.bobvila.com/articles/black-roof-stains-check-for-algae/

  24. I live in CT. My roof was very streaked with black and many areas had lichen patches. Quite a mess! Here we have a franchise called “Dr. Roof and Shine” that does roof cleaning. I used a local man. I wish I had before/after pictures. It came out just great! He never went on the roof. (Though I didn’t know he shouldn’t) The cleaning was done Sept. 2019. My home is a large cape with two car garage and a very large sun room. The job cost $515. There is some type of guarantee for how long the roof will stay clear. (I can’t find the paperwork at the moment that tells now long that is) The cleaning made the house look fresh and clean. Well worth it!

  25. The last time we had a new roof installed (almost 8 years ago) I chose a brown roof (which matches our brick), thinking that it would not show stains. However, over time it did develop some stains (especially on the north side… as you mentioned), which were more or less visible depending on the lighting and if the roof was wet, etc. Since I’m having my house painted soon, I decided to “start from the top” and get my roof cleaned first. I used a company called Aqua-Nomics and they did a great job! The whole roof looks visibly cleaner, not just the areas where there were stains. They were very careful with my shrubbery… pre-wetting it before, and rinsing it off afterwards. They do ask that tender potted plants and hanging baskets, etc. be moved away from the area being treated. Also, the two men who cleaned my roof were very polite and professional. Whoever you choose to do it, I definitely recommend getting it done!

  26. We had our roof cleaned a few years ago, they did a good job, and it looked very good, but they were not as careful with my plants, shrubbery etc as they should have been, the solution was rinsed off the roof and got onto several plants and shrubs and they failed to rinse it off thoroughly, so some of them did have damage to them. Just be sure they are careful with your landscaping.

  27. Warren Giering says

    I am looking forward to your follow-up on this project.

  28. After reading this I saw an add for shingles at Mennards in central Ohio. I took a picture but it won’t let me paste in comments. It has no black streaking guaranteed and lifetime algae resistance warranty. It is Pinnacle Pristine
    Architectural Shingles with Scotchgard protector. Something to look for next time you need to reroof.

  29. Anna North says

    I’m late to the comments, but wanted to let you know we had this done on our 2000 sq.ft. house 2 weeks ago. Turned out great. We paid $700 for roof cleaning and house pressure wash with a 5 year guarantee on the roof. I live in western NC.

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