Soft wash and pressure washing

A pressure washer pointed at a shingle roof strips the granules that protect the shingle from UV and weather, and that damage is exactly what voids a manufacturer's shingle warranty. It is not a risk worth taking to clean off moss or algae streaking.

Soft wash uses low pressure and a cleaning solution that actually kills the algae and moss at the root, then rinses off gently. Siding gets the same treatment for a related reason: high pressure can force water behind panels and trim, and what looks clean on the outside can turn into a moisture problem you cannot see for months.

Zebra striping, the light and dark banding left behind on a driveway or patio, is what an inconsistent pass looks like. It happens when the wand moves at an uneven speed or the passes do not overlap enough, so some strips of concrete get more cleaning time than the ones next to them.

Even, overlapping passes at a consistent distance and angle are what keep a concrete surface looking like one job instead of a patchwork of lighter and darker bands. It takes longer to do it that way, and it is the difference a homeowner actually notices once the surface is dry.

Sealing or staining a deck, fence or concrete surface has to happen on completely dry material, not on something that was just rinsed off. Sealing over moisture traps it underneath the sealer, which is how a fresh-looking finish turns into peeling or discoloration within a season.

That is why sealing and staining are booked as a second visit after washing, once the surface has had time to dry through, rather than tacked onto the end of the same day.