Roof Stains and Roof Cleaning: Frequently Asked Questions...
What are the black stains on my roof?
These roof stains, often mistaken for "roof mold," are the dead cells of a hardy algae called Gloeocapsa Magma. The algae grow on the north side of the roof that gets the least amount of sun and stays damp the longest. They feed on limestone filler in the shingles and grow and darken until removed. Airborne algae spores are carried from roof to roof and can infest a whole neighborhood.
Why are algae black?
The organism Gloeocapsa produces a dark-pigmented sheath to protect itself from ultra-violet rays. As the algae on your roof shingles die off, the dead cells accumulate and cause the black streaks sometimes referred to as "roof mold." These stains take months, or even years, to appear.
Can the algae on the roof shingles damage my roof?
Algae feed on the limestone filler used to give the shingles weight. Over time the ceramic granules protecting the surface of the shingle begin to loosen and wash off. This diminishes the roof’s ability to reflect heat rays which can overheat a roof increasing air conditioning bills and shortening shingle life. Algae on roof shingles also encourages other damaging biological growth, such as lichens and roof moss.
Are the moss and lichens growing on my roof harmful?
YES! Roof moss and lichens anchor into the top layer of the shingles and remove granules. Moss and lichens (see picture) grow up into the gullets (slots) of the shingles and along edges causing them to lift and make the roof more prone to wind damage and leaks. Acting like sponges, moss and lichens keep the roof damp causing even more growth.
Can I use chlorine or bleach to clean my roof?
People who have tried bleach have found that the result is temporary and the stains often come "roaring back." Chlorine must be handled with care and the surrounding area must be completely covered up; otherwise, it can kill the grass, shrubs, and flowers around the house. Chlorine runoff from the roof can void a home’s termite warranty due to the interaction with the protective chemicals in the ground.
"Thank you for doing an excellent job on my roof. My realtor was also impressed with the results. It's good to know a company that provides great quality service." Terrence J, Windsor Mill, MD.
Aren't there roof cleaning products on the Internet?
Some roof cleaning products are available online. However, our experience has shown that users are often disappointed with the results. The application of these products for cleaning roof shingles can be awkward and unsafe for anyone not used to working on pitched, wet surfaces. In addition, special tools are required to rinse these roof cleaners away without damaging the roof. My Clean Roof does the job right and uses the most reliable, safe roof cleaning solutions and specialized roof cleaning tools.
Will pressure washing harm my roof?
Yes! Cleaning roof shingles with pressure washing dislodges the protective granules from the surface of the shingles and scars the shingles. It does not solve the root cause of the stains – algae growing and feeding on the limestone filler in the shingle.
How much does a roof cleaning cost?
At My Clean Roof we base our pricing on these factors: (1) number of stories, (2) roof pitch and angles, (3) amount of staining, (4) if moss or lichens are present, (5) amount of roof to be cleaned, (6) and driving distance to the job. Call us for an estimate or email us a picture of your roof (see Contact Us page).
"Wonderful job. I'm so pleased I'm giving out your cards right and left." Jean W., Hampstead, MD.
Will the roof cleaning products hurt landscaping or pets?
Our cleaners are biodegradable and safe for grass, shrubs, pets and people. They contain no acids, solvents, chlorine, phosphates, peroxides or other harsh chemicals.
How long does a roof cleaning last?
Our cleaning agents produce great results that will last at least a couple years. After that the roof could begin to stain again because the same algae-producing conditions still exist - airborne algae spores, moisture on certain slopes of the roof, and the limestone shingle filler. We offer a 2 year warranty against re-staining. After that, we can begin our roof stain prevention treatment to avoid re-staining.
Can I just clean off the few, light streaks?
Spot cleaning is ineffective. The minor stains or streaks on the roof indicate the roof has lost its ability to fight off the algae, and the stains will spread as summer humidity increases.
Can I just clean the front roof? That's all that's dirty.
Yes! That's most of what we do for homeowners.
Do you clean slate or cedar shingle roofs?
No, we do not.