Pressure washing cleans by force — water hitting a surface hard enough to blast material off it. That's exactly right for a concrete driveway and exactly wrong for an asphalt shingle roof, because the 'material' a pressure washer removes from shingles includes the granules that make them work.
Those granules are the shingle's armor: they block UV from the asphalt underneath and carry the fire and weather ratings. Every shingle sheds some granules over its life — but a pressure washer strips them by the pound, aging a roof years in an afternoon. Roofing manufacturers say plainly not to pressure wash shingles, and it can put warranty coverage in question.
Soft washing flips the equation: low pressure — closer to a garden hose than a pressure washer — and a cleaning solution that does the actual work. The solution kills the algae and mildew at the biological level; the rinse carries it away. No blasting, no granule loss.
The bonus is longevity of the clean itself. Pressure washing knocks the visible algae off but leaves the organism rooted in the surface, so the streaks return quickly. A soft wash kills the growth, and the roof stays clean until new spores recolonize — years, not months. Gentler and longer-lasting is a rare combination; this is one of the few places you get both. If your roof is streaked, we'll take a look — free, like every estimate.
