Roof shingles become dirty over time. They are exposed to wind, rain and other weather elements that not only cause dirt to form on the shingles, but also mold and mildew. Stained shingles take away from the overall neat appearance of the exterior of the home. You can successfully clean shingles by using oxygen bleach. Unlike chlorine bleach, oxygen (oxy) bleach will not discolor or damage the shingles. When oxy bleach is used, oxygen is released for cleaning and bleaching stains without distorting the color. Using oxy bleach on shingles will leave the shingles clean, stain-free and looking like new.
Mix a solution of oxygen bleach and water into a pump-style garden sprayer. The bleach-to-water ratio will depend on the concentration of oxygen bleach you are using. Follow the directions of the label of the oxygen bleach for proper mixing instructions.
Use a ladder to reach the shingles on the roof. Depending on the slope of your roof, you may need to actually climb onto the roof to clean the shingles. Use extreme caution when climbing on the ladder and/or walking on the roof.
Wet the entire roof with plain water. Use a garden hose rather than a power washer. Although a power washer will likely remove dirt and grime, the power of the water may damage the shingles.
Spray the oxygen bleach mixture onto the shingles. Apply one coating of oxygen bleach to the darkest stained areas first, then coat the entire shingled surface with the spray. Follow this by spraying another coat of the oxy bleach onto the darker stains. When applying the spray to the shingles spray the bleach and water mixture so that it flows down the roof, rather than up. This will prevent water from getting up under the shingles and leaking into the house.
Allow the oxy bleach mixture to sit on the shingles for about 15 minutes. Use a garden hose to rinse the stains and cleaning solution from the roof. Set the garden hose on the spray setting with the highest pressure water and hold the nozzle close to the shingles when rinsing. This will remove any stains that were loosed up by the oxygen bleach.
Apply a second coat of oxygen bleach if the stains persist. Be sure to rinse the roof with clean water after each application of oxygen bleach.