No, it is not okay to pressure wash a shingle roof, and doing so can cause serious damage that voids manufacturer warranties and shortens roof lifespan. Asphalt shingles are protected by ceramic-coated mineral granules embedded in the asphalt that block UV radiation, provide fire resistance, and add weight for wind resistance. Pressure washing, even at moderate pressures of 1,500 PSI or more, strips these granules off, leaving bald spots where black asphalt is exposed to direct sun, accelerating aging and deterioration. Pressure washing can also lift and break shingle tabs, force water under shingles and into the attic causing leaks and deck rot, and damage flashing and sealant bonds. All major shingle manufacturers including GAF, Owens Corning, Atlas, and CertainTeed explicitly state in their installation instructions that pressure washing voids their limited warranties. Professional roof cleaning organizations also advise against pressure washing. Instead, use shingle-safe low-pressure methods. For algae, use oxygen bleach solution or commercial products like Spray and Forget, Wet and Forget, or Roof Shampoo applied with a garden sprayer and rinsed gently with garden hose pressure. For moss, use zinc sulfate or potassium salts to kill moss, then gently sweep dead moss with a soft broom after it dies. If you need professional cleaning, hire a roof cleaner who uses low-pressure chemical cleaning methods, not pressure washing.
1 votes
Marked as accepted