Absolutely not! The Canadian Asphalt Shingle Manufacturers Association recommends that under no circumstances should a asphalt roof be pressure washed. Despite what some contractors will tell you, even a low PSI pressure wash will damage the granules that protect shingles from the sun. In addition, most roof warranties will be voided if a pressure washer is used to clean the roof. If in doubt, check with the company that installed your roof. When you work with roofs as often as we do, you understand just how fragile they are, thats why we always recommend the gentlest method of roof cleaning possible.