Before venturing out onto the roof, let someone know you’ll be doing so. That way, if you suffer an accident or injury on the roof, they’ll be able to find you.
When using the leaf blower to clear debris, blow from the ridge toward the edge of the roof. This will prevent branches and other debris from lodging beneath the shingles’ edges. [3] X Research source There’s no need to wash the shingles before using the chemical cleaner.
Additionally, don’t clean your asphalt tiles on days when the cleaning agent could freeze. In other words, only clean your asphalt shingles on days when the temperature will remain above 32 degrees Fahrenheit (zero degrees Celsius). Stay off the roof during very windy days. [5] X Research source
Commonly used cleaning agents include Roof Shampoo and Shingle Roof Mold Cleaner OX. If you don’t want to buy a commercial cleaner, you can easily make your own by mixing equal amounts of laundry-strength chlorine bleach and water. [8] X Research source
Generally, you’ll need to unscrew the tops of the spraying device and the cleaning agent, fill the spraying device, then screw the tops of the cleaning agent and the spraying device back on. Don’t use a pressure washer to apply the cleaning agent. Doing so can damage your asphalt shingles. Use a low-pressure sprayer rated about 30 PSI. [10] X Research source
The exact method by which you can spray the asphalt shingles varies slightly depending on the type of spraying device you’ve decided to use. Consult manufacturer directions for more information. The amount of cleaning agent you’ll need to use depends on the number and size of the asphalt shingles you wish to clean. Generally, the more shingles you want to clean, the more cleaning agent you’ll need. You can identify asphalt shingles that need to be cleaned by looking for black, green, or blue stains. This indicates the presence of algae or moss.
If you’re having a hard time getting your asphalt shingles clean, let the roof dry, then spray it with the cleaning agent and rinse it with water again.
Alternately, you could affix a strip of zinc or copper just below the ridge of your roof. The zinc or copper particles will trickle down the roof when it rains, inhibiting algae growth.
