Does vinegar hurt roof shingles?

Vinegar can hurt roof shingles if used improperly, especially in concentrated form or with improper application, though diluted vinegar is sometimes used as a mild cleaner. White vinegar is acetic acid, typically 5 percent acidity for household vinegar, and stronger horticultural vinegar can be 20 percent. Acetic acid can degrade asphalt over time, strip protective granules if scrubbed aggressively, and corrode metal flashing, gutters, and fasteners. If you spray undiluted vinegar and leave it on shingles in hot sun, it can dry out asphalt and cause premature aging. However, a diluted solution of one part vinegar to several parts water is sometimes used by homeowners as a gentler alternative to bleach for killing moss or algae, and when rinsed thoroughly with low-pressure water after a short dwell time, it may cause minimal damage. Professional roofing organizations and shingle manufacturers like GAF and Owens Corning do not recommend vinegar as a roof cleaner and instead recommend oxygen bleach or commercial shingle-safe cleaners like Spray and Forget. Vinegar is also less effective than zinc sulfate products for killing thick moss and can harm surrounding plants and landscaping if runoff is not diluted. If you choose to use vinegar, use only highly diluted household vinegar, apply on a cool overcast day, avoid scrubbing, rinse thoroughly with garden hose pressure, and protect plants. For best results and warranty compliance, use products specifically labeled safe for asphalt shingles.