Pro Roof Washers
Your Roof  Cleaning Experts
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 Pro Roof Washers Frequently Asked Questions

What are those black streaks on my roof? 

The technical term for the black stains is Gloeocapsa Magma which is a type of algae.  Fiberglass and asphalt shingles, which are most common on residential homes, are manufactured with limestone as a filler.  This limestone is a source of food for this type of algae. These shingles hold moisture and organic "bacteria food" material longer (especially on the North-side of the roof in the Midwest) than the paper/asphalt/ceramic shingles of 20+ years ago.   

Once the black stains have become noticeable, the stains will continue to worsen year to year. Most "experts" within the subject area believe the algae, if left untreated, will cause premature aging, rotting, and/or granule loss.

Where did it come from?

 Algae, moss, lichen spores are in the air and  take hold on a roof through wind and animals.  The area that gets the least amount of sunlight is a hospitable environment for the algae to thrive and grow. The north side of your roof is most likely that environment and is most common.  However, I have seen it grow on all sides, so we always treat all sides of the roof.  Of course the sides with heavier stains gets the heavier treatment.  Does it spread??? Yes! It spreads from house to house by wind and animals (birds, squirrels etc)  If you look at your street you will see many houses in a row with the black stains, except for the homes with new or newer roofs.  It usually takes approximately 7 years for a brand new roof to show signs of infection. It will start with a dot then eventually grow to a streak.  If you have stains on the front of your house, most likely your neighbors across the street has them on the back of their house. Untreated, its only a matter of time till the entire roof has visible stains.

What is your cleaning process and what type of cleaner do you use?

There are basically 3 different types of chemicals that are used to clean your roof:

  1. Oxygen based cleaners - Like OxyClean.  Although safe for the environment, plants, and animals, is not effective on cleaning roofs without the use of pressure to spray it off which is not a recommended process. Think about it, if it cant kill a plant, how can it kill the living organism that is eating your roof?
  2. Sodim Hydroxide.  Also a non-effective and non recommended method requiring pressure to remove stains.
  3. Sodium Hypochlorite- Is the preferred method and the method we use.  With Sodium Hypochlorite mixed with water and a detergent based surfectant , the stains are immediately gone.  No pressure is ever used to remove the stains.  We all know the power of bleach and what it does to mold and mildew. Well its no different on your roof.  This method is the only method that is recommended by the ARMA (Asphalt Roofing Manufacturers Association) and GAF (North America’s largest shingle manufacturer). When done correctly, this process is safe for your home, family, pets, and any adjacent landscaping. . 

What will your cleaner do to my plants?

 We go to great lengths to rinse down all plants and landscaping surrounding the house before, during, and after the application. The result is that what little overspray there is is completely diluted to the point of being harmless.  You may even notice that your landscaping in these areas looks especially green and vibrant in the days following the cleaning due to all the watering!

What is your guarantee that the stains dont return?

Whole roof cleanings come with a two-year guarantee that your roof will remain algae-free, but you can generally expect it to stay clean and beautiful for at least four years or longer before the algae becomes noticeable again. Every situation is a little bit different, and it’s not unusual for a roof to stay clean for five years or more after a professional non-pressure cleaning. 

Partial roof cleanings are not recommended and DO NOT come with a guarantee.  It’s important to understand that roof algae is not visible to the naked eye in its early stages, so while you may not see it in some areas, it’s most likely already there and beginning to develop.  The growth of algae is slowed in areas that receive maximum sunlight, but eventually it will become visible!  That’s why it’s so important to treat the entire roof surface.

 Do you offer any other services?

Yes.  We also offer whole house washing, concrete cleaning, deck restoration, gutter cleaning on the insides of the gutters and gutter whitening on the outside using a commercial grade gutter restorer. (If you have ever tried cleaning the gutters to bring back the whiteness, then you know that its almost impossible with store bought or household cleaners.)

 How much does it cost?

  An average roof cleaning price is in the $300-$450 range.  We provide, prompt, no-hassle estimates, so please call us or send a message through our contact form. 




 What forms of payment do you accept?

We prefer that our customers pay by cash or check, but if you’d like to pay by credit card that can be arranged. Checks should either be presented to us upon completion or left on your front door if you won’t be home. Thank you!

Why REPLACE your roof when you can clean it! 
Request a FAST QUOTE now from Pro Roof Washers  440 521-2622 or

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