There are many ways to clean your roof, some are better than others, and all have their place. That said, Performance Roof Cleaning doesn't generally promote the use of high-pressure washing on your roof. Simply, using a high-pressure washer (On a composite or asphalt shingle roofs) shortens the life of the roof. It removes granules and can easily tear a shingle creating a 'fault' in your rooftop defenses. Cedar Shake roof surfaces are not immune to problems associated with high-pressure washers either.