Q: Are you licensed and insured?

A: Yes.   We are licensed and insured to do business in the state of North Carolina.

Q: Why does my roof turn black?

A: The short answer is that it is algae. It grows on the north side and shaded areas of your roof.

The long answer: Gloeocapsa Magma is the primary species of  algae causing your roof to turn black.   Milled or compounded limestone is used as a filler in roof shingles to add weight and flexibility for the shingle.  Shingle manufacturers started using limestone, which is calcium carbonate,  in the late 70’s when the first energy crises hit and petroleum became expensive and was in short supply.  Limestone is apparently a superior filler product and most shingle manufacturers are reluctant to go back to the old methods or to try new products.

The problem, is that algae loves limestone!  Because of it’s alkalinity and solubility, it provides a stable environment and a food source for the algae to flourish.  It thrives in warm, humid environments like the Carolinas  and normally appears on the north facing slope or shaded areas of your roof  where the lack of sun and abundant moisture (like morning dew) supports its growth.

These Algae spores are carried by the wind and land on your roof.   You may first notice it as little black stains on your roof that just seem to explode over the course of a year.  It’s growth is exponential, the more it spreads the more moisture it can hold to aid it’s growth.  As it grows, it will spread to adjacent homes  which is why you will see it on so many roofs in the same area.  Then it is time for a roof cleaning.

Q: Will algae damage my shingles?

A: The shingle manufacturers say that while the algae is unsightly,  it does not damage or harm the shingles.

After many years in the roof cleaning business, I can say that it does seem to do some damage.   Older roofs with a lot of algae seem to lose more granules.    As the algae feeds and spreads, it loosens this protective   layer of surface granules which play a very important part in solar  reflectivity.

The loss of these granules, combined with the black growth   spreading across you roof will cause your roof to absorb heat from the sun up on a sunny day. Your attic will be much hotter than necessary and this usually translates to the upstairs of your home being a little warmer, as the heat from the attic radiates into that upper floor. While this might be fine in the winter, it can be a source of higher electric bills in the spring and summer months as your air conditioner struggles to keep up.

Q: How long will my roof stay clean after you finish?

A: The average roof cleaning will usually last three or more years depending on the amount of shade around your home. If you are under a lot of trees and the roof stays shady for a good portion of the day, then the algae will certainly return a little faster. Homes that do not have many trees around them tend to stay cleaner much longer. Just remember, it is algae and this is North Carolina. Heat and humidity play a big role in helping the algae thrive.

Q: My roof has moss on it. Can this be cleaned?

A: The answer is yes. Over the years we have developed methods to effectively clean moss off of roofs. If you are dealing with a letter from your insurance company that is requiring you to clean the moss and algae of off your roof, please tell us about it when you call or email. We have helped many homeowners deal with that problem.

Q: How do you clean my shingles?

A: We use battery operated pumps to lightly dispense the cleaning detergents on the roof.  No pressure washers are ever used in our process.  The detergents do all the work to clean the roof and we then rinse with garden hoses.  This follows the method the shingle manufacturers themselves recommend, meaning no pressure, and this is also the process our insurance makes us follow.

Q: I have seen some roof cleaning websites with the  “Certified Roof Cleaner” logo?  Is your company certified?

A: There is no “recognized” certification process in our industry, so generally speaking, any claims to certification that you may see in the roof cleaning industry are usually nothing more than a piece of paper and a nice logo purchased online.    There are several websites that have recently appeared, where, for a fee, anyone can subscribe and get some online roof cleaning training, a tee shirt and a certificate implying they are now certified to go clean roofs.   These sites have a tendency to prey on the newer roof cleaning companies as they enter the work place and get caught up in the infomercial mentality of a certification.

So the answer would be no, we are not certified.  We clean hundreds of roofs every year and rely on that experience to provide a high level of service to our customers.

Q: Does bleach, damage shingles?

A: Bleach does not damage shingles.  I am not sure why this question is still asked, but there is a reason it started.

Years ago, when roof cleaning was in its infancy, there were several methods used to clean a roof.  Sodium Hydroxide and Sodium Hypochlorite (bleach) were the two roof cleaning chemicals prevalent in the industry at that time.

A very small segment of the roof cleaning industry used sodium hydroxide, and these were the guys that started the “bleach damages shingles” rumor you see on the internet today.   Once something is on the internet, it is hard to remove, so you will still see the subject pop up while doing internet searches.

Companies that use sodium hydroxide are still around, but they are a definite rarity these days.  Most of them have gone out of business including two in our area.

Professional roof cleaning companies, long ago, figured out that using sodium hydroxide is a dangerous, messy and cumbersome cleaning process that can actually damage a roof, so they  switched to Sodium Hypochlorite (bleach).

These days, most professional roof cleaning companies use bleach in their roof cleaning mix.  The Asphalt Roofing Manufacturers Association (this would be the trade  association that represents companies that make shingles) have issued a technical bulletin which describes the proper method of cleaning a roof involving the use of bleach, soap and low pressure.   GAF,  a major shingle manufacturer also has one of these bulletins.

The non pressure, or low pressure cleaning process is the only method approved and endorsed by these shingle manufacturing companies and it is the only method our insurance company allows us to use.

Think about this: If  bleach actually damaged or “dried and curled” shingles, would we not  see a plethora of lawsuits against ARMA and the shingle manufacturers? Since there are none, and these shingle manufacturers and ARMA continue to favorably endorse this cleaning method, we think it is safe to say that bleach does not damage shingles.

There is currently, a small, national campaign to revive the use of sodium hydroxide.  It is a group of entrepreneurs who are opening franchises touting “Eco friendly” roof cleaning methods.   Sodium hydroxide is not eco friendly and once it is on your roof, it will turn very black and greasy.  The only way to get it off is to use a pressure washer, and it makes a mess of both your roof, and surrounding landscape as it comes out of the gutters.

The roof cleaning industry is growing in our area.  Like any industry, there will be the “hacks” that see an opportunity to make some money.   If someone wants to clean your roof and there is a pressure washer involved in any way, shape or from, we would suggest you politely thank them for their time and send them on their way.  I have posted about the use of a pressure washer on a roof in one of my blogs.

Q: Will your detergents kill my plants and shrubs?

A:  No.  We take many precautions to ensure that the roof cleaning is done safely and effectively.  Yes , it is a light bleach solution, but it is easy enough to control and it is by far a lot safer than our brothers on the other side of the aisle will lead you to believe.  We clean hundreds of roofs every year and  some of them are in very exclusive neighborhoods and have some very expensive landscaping!   We have a variety of proprietary  methods we use to ensure that no plant, grass or shrub is damaged.

Q: I have seen some “Do it yourself” roof cleaning solutions at my local home improvement store.  Are these cleaners effective?

A: It depends on your definition of effective.  I have seen instances where they have worked after a couple of applications and a couple of months waiting.  But, for the most part, they are a product in the “gimmick cleaning” family that are really not that effective.  The best way to answer this question would be to tell you to pick one of the products, then go to amazon.com or similar site and read the customer reviews.   The reviews mirror the results I have seen in the course of our daily business.

A true story: I had a customer call me and ask if I could  clean his roof.  He wanted me to provide labor only, as he had already purchased the chemicals at the local home improvement store.  It turned out that he fell off his roof while applying the chemicals and was not in the mood to try it again.  I told him that my insurance does not allow us to use those chemicals and thanked him for the opportunity.

Do zinc strips work to help prevent black roof stains?  Are the effective?

A: Based on our experience with them I would say they work, but only for a limited time.  The effect of the strips seems to degrade over a period of a few short years.  There is also a distance factor.   The width of the zinc strips determines how much area of the roof it can cover.

Below is a picture of a house with a zinc strip on the roof.   We ended up cleaning the roof (pictured below) for this customer.  (Check out the photos section)  You can see that the strip had an effective range of a few feet and then it ran out of strength.  It may have worked when first installed, but as you can see, not for long.    It seems you would need to place wider strips at varying points down the roof in order to have effective coverage.  If you don’t mind the way that would look, then it might be something to look into.


I wrote a quick article about zinc strips.  There is another picture there as well.

Q: Can I seal my roof to prevent algae growth?  I have seen a few companies that sell a roof sealant / preventative.

A:  I have seen these companies and I am not sure how effective they are.  They must first clean the roof and then apply the sealant which appears to have a biocide in it.

I do know that this is another industry practice that is frowned on by the shingle manufacturers.  You can read about field coatings here .  If it is something you are thinking about, we recommend doing lots of research because it seems like the process creates more problems than it solves especially with any warranties you may have.

Q: What happens if I copy your material onto my website and you catch me?

A: This question /answer is not directed at our potential customers.   It is posted here for the lazy web designers who have a penchant for using the copy/paste function.  Roof Refresh is one of the older roof cleaning companies and our web pages have a lot of useful information that get a lot of attention from potential customers and our roof cleaning competition.

With the roof cleaning industry growing so fast, this FAQ page and our picture gallery page appear on  other roof cleaning websites on a regular basis.  These are usually new roof cleaning companies that have no content or  pictures of their own work because they are brand new to the industry.

So, the answer for you newbies is this: The material and pictures on this website is the property of Roof Refresh and my only advice would be to please do not copy it.

If you choose to ignore that advice and we find you, (which is pretty easy) a polite email will be sent asking you to remove it immediately.  If that fails, a complaint will be immediately  filed with your hosting company.

From past experience, I can tell you that they take it these complaints seriously and will shut down your site until the copied material is removed and we approve the changes from our end.  We are pretty busy with roof cleaning, so the approval may take a little time.

To paraphrase Fred Thompson in the movie “Days of Thunder”, ” we are going to do a Japanese inspection” of your website before we sign off.


Q: What other services do you provide?

A: We also pressure wash homes and concrete and clean out gutters.