One of the biggest misconceptions homeowners have is that more pressure means cleaner. For roofs specifically, that’s usually backwards.
A pressure washer can strip granules straight off asphalt shingles in seconds, permanently shortening the life of the roof and frequently voiding manufacturer warranties in the process. That alone is why roof cleaning has to work differently from driveway cleaning.
Soft washing solves this by relying on a specialized cleaning solution to break down moss, algae and lichen at low pressure. The solution does the work of lifting organic growth from the shingle surface; the water is there to apply and, where appropriate, rinse — not to blast material off by force.