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Frequently Asked Questions (FAQs)

What Causes Roof Stains and Other Roof Issues?

Black or very dark roof stains are caused by a hardy type of algae, Gloeocapsa magma (often referred to as blue-green algae), which grows on the roof and feeds on the limestone filler in asphalt shingles.  Often the algae originates in standing water as well as in lakes and ponds.  Wind, birds and other wildlife carry the algae spores to roofs from the water sources and then from roof to roof.  Most of the stains begin on the north facing side of the roof where the lack of sun keeps the roof from drying out completely.  The algae normally grows for quite some time before stains are noticed.  As the algae grows, it holds more moisture on the roof thus accelerating the growth process. 

Green roof stains are normally caused by mold or mildew.  Other stains are caused by lichen and moss.  Roof-Be-Clean®eliminates and prevents stains caused by all these sources.

Years ago, stains on asphalt shingled roofs were not a significant problem.  Today it is a big problem because the design of asphalt shingles has changed over time. For the last 30 years or so, asphalt shingles have been manufactured using limestone as the base filler - this is the core of the problem as this design encourages the algae that causes the stains to spread across the roof.

There are a number of types of stains and these can vary by the part of the country in which you are located.  Roof-Be-Clean® handles most of these issues.  However Roof-Be-Clean® does not work on stains caused by rust, paint or creosote (from wood burning stoves).

If I am not Concerned about the Looks of my Roof, should I be Concerned about Roof Stains?

Yes, very much so.  It is bad enough that roof stains are ugly, unfortunately they also lead to roof damage.  The granules which protect & color the roof are dislodged over time.  The stains hold moisture to the roof's surface and can cause decay & rot of the roof's underlayment.  Not only is your roof being discolored by the stains, but life of the roof is shortened leading to an early roof replacement.


Why is Power (High-Pressure) Washing or Brush Cleaning the Roof Not Recommended?

Asphalt shingled roofing is coated with granules that not only protect the roof but also provide the colors for the roof. When the roof is power washed or brushed cleaned, it breaks the bond that holds the granules to the roof allowing them to wash away.  Asphalt shingles are easily damaged as anyone who has walked on a roof can attest - just walking on the roof dislodges the granules.  The use of high pressure washing and/ or brush cleaning is very damaging to the roof – the force of the high-pressure discharge and/or the brushing action does significant damage.  Power washing is not even recommended for asphalt pavement so it certainly should not be used on asphalt roofing!

How do I Determine the Correct Blend of Roof-Be-Clean® to Use?

 Roof-Be-Clean® has a dual action formula with both a cleaning element and a prevention element.  To handle different roof situations, Roof-Be-Clean® is provided in three different blends of the cleaning/prevention elements in order to focus on specific needs:

Blend 1 – Use for highly stained roofs as well as roofs with moss and/or lichen growth.  Heavy emphasis is on stain/growth removal.

Blend 2 – Use for roofs with early signs of staining.  Balanced for removal & prevention.

Blend 3 – Use for currently clean roofs.  Emphasis is on prevention but contains enough cleaning element to eliminate stains that are in an early, invisible, stage of development.

For best results, you should choose the blend that best meets the current stain status of your roof – highly stained or with existing moss/lichen (Blend #1), lightly stained (Blend #2) or clean (Blend #3).

How do I Determine the Size of my Roof?

For the purpose of applying Roof-Be-Clean®, it is only necessary to know approximate roof size (not exact as would be required for a re-roofing project).  Start with the approximate heated square foot size of your home – plus non-heated roofed areas.  If your home is two-stories, divide the square footage by 2 (i.e., only one roof for both floors).  Multiply by 1.3 (1.4 for very steep roofs) and that gives a rough estimate of the roof size.  If parts of your home are one-story (e.g., a garage) and other parts are two-stories, estimate each part separately and add the results.


For example: for a single-story house with 50 feet by 30 feet outside dimensions, heated square footage would be 50 X 30 = 1,500.  Approx. roof size would be 1.3 X 1,500 = 1,950 sq. ft.

Another example: for a two-story house with 50 by 30 outside dimensions, heated square footage would be 50 X 30 X 2 stories = 3,000.  Approx. roof size would be 1.3 X 3,000/2 = 1,950 sq. ft.  Add a single story 20 X 20 garage for an additional 20 X 20 = 400 sq. ft.  Roof size of the garage would be approx. 1.3 x 400 = 520 sq. ft.  Total roof size for this example would then be 1,950 + 520 = 2,470 sq. ft.


How Much Roof-Be-Clean do I need?


Coverage is based on the size of your roof (see above) and the dilution ratio (amount of water mixed with 1-gallon of Roof-Be-Cleanâ being used.  See "Roof Applications" tab for correct dilution ratio based on your specific situation - cleaning highly stained roof, cleaning lightly stained roof or clean roof treatment / preventative maintenance.


For a highly stained roof, we normally recommend 2-gallons of Blend #1 for an average size house in order to provide for multiple applications.  For a lightly stained roof, 1-gallon of Blend #2 might be sufficient, however 2-gallons is better value when purchased initially. 


For a clean, average size roof, 1-gallon of Blend #3 should suffice for preventative maintenance for 2 applications (2-3 years of protection).


What Type of Sprayer is Best for Applying Roof-Be-Clean®?

Roof-Be-Clean® is formulated for application with an ordinary, garden pump-sprayer.  Since application is normally done from a ladder at the roof eave, a backpack type sprayer is recommended.  This type of sprayer provides several advantages over the handheld type.  Most important, it is safer since it frees a hand to hold the ladder.  Pumping is easier since a pumping lever is located at the side (some units allow switching the lever based on right or left hand use) so tank pressurization is accomplished by using only one hand – again a safety consideration.  Also, backpack sprayers normally provide higher operating pressures making it easier to spray to the top of the roof from the eave.  These sprayers are normally available at home and garden supply stores as well as hardware stores.


Hose-end sprayers that we are familiar with will not work as these dilute too much (i.e., too much water is added for each ounce of chemical).


Do not stand on the roof – it can become slippery when wet!


When is the Best Time to Spray my Roof?

It is best to spray in the late afternoon when the roof is cooling down.  Also, the roof should be dry - the dryer the better.  When it is dry, the stains will soak up Roof-Be-Clean® like a sponge.  Also, the cooler the roof the better Roof-Be-Clean® will soak into the stains.  However, the temperature should not be below freezing when you apply Roof-Be-Clean® or for 2-3 days prior to application.  If it is below freezing, the stains might contain frozen water which would prevent good absorption of Roof-Be-Clean® . 

Also, it is best that it not rain for 24 hours after application. 
Don't spray when it is windy since too much product will end up in places other than the roof.

What Temperature is OK for Application?

Roof-Be-Clean® can be applied over a wide range of temperatures, however some general parameters should be observed. During the hot months, it is best to spray in the late afternoon when the roof is cooling down or in the early morning when the roof is not so hot. A cooler roof will allow Roof-Be-Clean® to soak into the stains better by avoiding rapid evaporation. The temperature should not be below freezing when you apply Roof-Be-Clean® or for 2-3 days prior to application. If it is below freezing, the stains might contain ice crystals that would prevent good absorption of Roof-Be-Clean®.

Should I Wet my Roof Prior to Application?

NO!  NO!
The roof should be dry when Roof-Be-Clean® is applied - the dryer the better.  When it is dry, the stains will soak up Roof-Be-Clean® like a sponge.

How Often Should my Roof be Treated with Roof-Be-Clean®?

One of the outstanding aspects of the Roof-Be-Clean® formula is its stain blocking capability.  Just like other preventative maintenance measures taken around the home and yard (i.e., application of pre-emergent crab grass control products, etc.), Roof-Be-Clean® should be used on a scheduled basis to keep your roof stain free.  This preventative maintenance will protect your roof from the damage caused by stains as well. 

For a currently clean roof or for maintaining a clean roof, Roof-Be-Clean® should be applied every 12 to 24 months.

Are there Situations when Roof-Be-Clean® should Not be Used?

Roof-Be-Clean® should not be used on a roof when the house has gutters made out of galvanized steel.  These gutters are not seen much anymore but some very old houses may still have them.  The same is true for a house with gutters made out of zinc.  Zinc gutters are very rarely used in the United States (these are more often found in Europe.

Roof-Be-Clean® handles most of the common roof stain issues that occur.  However, Roof-Be-Clean® does not clean rust or creosote stains. Creosote stains are caused by the chemicals that come out of the chimney due to buring wood in a fireplace or wood burning stove.

Is Special Product Pricing Offered to Cleaning Contractors?

We do offer discounts to companies that provide cleaning and other services to homeowners and businesses.  If interested, please contact our Contractor Sales Division at (803) 230-8601 and we will be happy to discuss your specific business needs.

Is Roof-Be-Clean® Manufactured in the USA?

YES!  Roof-Be-Clean® as well as ALL of our products are manufactured in the USA.   We also make every effort to buy only American made supplies for use in our business.

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