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How to Clean Creosote From an Asphalt Shingle Roof

Amanda Flanigan

Wood that burns at low temperatures has a greater chance of developing incomplete combustion. When incomplete combustion occurs, creosote will appear. Creosote is a black, oily residue -- similar to soot -- that covers any surface that it comes in contact with. When creosote builds up on an asphalt shingle roof, you should remove it as soon as possible. An excess buildup of creosote can quickly become a fire hazard. Unfortunately, certain products -- such as chlorine bleach -- can damage asphalt roofs and create an even bigger problem than the creosote.

Chimneys are a common cause of soot and creosote stains on roofs.
  1. Create the cleaning solution by mixing 2 c. oxygen bleach with 2 gallons warm water in a bucket. Fill a clean garden sprayer with the mixture.

  2. Place a ladder against your home and have a friend or family member hold the ladder steady while you climb up it and onto the roof. Ask your friend or family member to hand you up the bucket filled with the mixture and the garden sprayer.

  3. Rinse the roof with a water hose. Use the water pressure to push leaves, moss, sticks and other debris off the roof.

  4. Spray the creosote with the mixture inside the garden sprayer. Saturate the creosote completely with the mixture and let sit for 10 minutes.

  5. Dip a brush broom into the bucket filled with the mixture and begin scrubbing the saturated creosote. Scrub in a vigorous back-and-forth motion. Continue scrubbing until you have removed the creosote from the asphalt roof.

  6. Rinse the roof clean with the water hose. Repeat the process as needed.