Roof shingles are exposed to a lot of wear and tear, as extreme heat, sun, wind and precipitation come into contact with them. It is not uncommon for roof shingles to turn black over time. When that happens, it is generally caused by mildew, algae, mold or dirt stains. These black streaks are unsightly and can diminish the appearance of the entire exterior of the home. Remove black stains from roof shingles to preserve the appearance of your home's roof.
Chlorine Bleach and Trisodium Phosphate
Step 1
Wet down the roof with water from the garden hose. It is important that the roof be wet when the cleaning mixture is applied, or it may evaporate before it has a chance to work.
Step 2
Fill a large bucket with 1 gallon of hot water, 1 qt. of chlorine bleach and a quarter-cup of trisodium phosphate. Transfer the ingredients into a garden sprayer and shake the sprayer a couple of times to mix up the ingredients.
Step 3
Spray a generous amount of the cleaning solution onto the black areas of the roof shingles. Follow up by spraying another layer onto the entire roof.
Step 4
Allow the mixture to sit on the shingles for 15 minutes, then rinse the roof well with water from the garden hose. Set the nozzle at the highest pressure setting and hold it 12 inches from the shingles. Rinse from the top of the roof down to avoid re-staining the shingles with the dirty water.
Oxygen Bleach
Step 1
Wet down the roof with water from the garden hose. It is important that the roof be wet when the mixture is applied, or it may evaporate before it has a chance to work.
Step 2
Fill a large bucket with 1 gallon of hot water and 4 oz. of oxygen bleach powder. Wait about five minutes for the powder to completely dissolve, then fill a garden sprayer with the mixture.
Step 3
Spray a generous coating of the oxygen bleach mixture onto the black areas of the roof. Follow up by spraying down the entire roof with the mixture.
Step 4
Allow the oxygen bleach to sit on the shingles for 20 minutes. Set the nozzle at the highest pressure setting and hold it 12 inches from the shingles. Rinse from the top of the roof down to avoid re-staining the shingles with the dirty water.
Tip
Clean your roof on a cloudy day to prevent the cleaning solution from drying too quickly.
You can choose to clean only the black areas of the shingles, but this may leave an uneven color to the roof. Cleaning the entire roof is recommended for an even appearance.
Discard any excess oxygen bleach solution after it has set for six hours. After that time, it loses its effectiveness.
For tough black stains, scrub the cleaning solution into the stained area of the roof shingles using a scrub brush attached to an extension pole.
Warning
Use caution when working on a ladder or on a roof. Wear rubber-soled shoes to protect from slipping.
Cover landscaping below with plastic sheeting to protect it from the cleaning solutions.
Wear protective eyewear and clothing that covers your arms and legs to protect yourself from the cleaning solutions.