To clean the roof with bleach, mix trisodium phosphate and chlorine bleach with water, spray the solution onto the roof, and rinse the roof with clean water after 15 minutes. Oxygen bleach can be used in place of chlorine bleach.
Before cleaning the roof, cover the surrounding vegetation with plastic sheeting, or water the vegetation thoroughly to prevent the cleaning solution from damaging nearby plants. To clean the roof, mix 1 quart of bleach, 1/4 cup TSP and 1 gallon of water in a pump sprayer. Spray the cleaning solution on the roof, and allow it to remain for 15 minutes. If necessary, reapply the cleaning solution to keep the roof damp during the 15 minute waiting period. Rinse the roof with clean water.
To clean the roof with oxygen bleach, combine the recommended amount of powdered oxygen bleach with water in a pump sprayer, and spray the roof with the cleaning solution. Allow the cleaning solution to remain on the roof for at least 10 minutes, and scrub the roof with a soft brush to remove algae and other debris. Rinse with clean water. When cleaning the roof with chlorine or oxygen bleach, use caution as the cleaner can make the surface of the roof slippery.