Rinse-down

ARMA's shingle bulletin ends its procedure this way: "rinse the solution from the roof by gently spraying the surface with water." GAF's own mixture instruction closes the same way, in its own words: "let sit on the roof surface for up to 20 minutes, and rinse with low-pressure water."

The Metal Roofing Alliance gives metal its own version: "Let the solution stand for 5 to 10 minutes, before thoroughly rinsing the surface with plain water." Three publishers, two kinds of roof, and a rinse at the end of each procedure. Whether a roof is rinsed after a soft wash, and why, is answered on whether a roof gets rinsed after soft washing.

ARMA's Algae & Moss page sets its shingle rinse right after a dwell of 15 to 20 minutes, in the words "and then rinse thoroughly with low pressure water." The minutes belong to dwell time; rinse-down is the step ARMA puts after them.

ARMA ties the two together with a caution: extended dwell times may be necessary, but the solution should not be left to dry completely before the rinse. The sequence is set out in order on the soft washing method page's apply, dwell, rinse section.

ARMA describes a later effect that is easy to mistake for a rinse. Its Algae & Moss page says that after its bleach treatment, "Algae will disappear and ... away with subsequent rains," which is about the algae after the treatment, while its rinse is the step that ends the dwell.

Whether rain can stand in for that rinse is answered in the roof cleaning page's rain question.

The Metal Roofing Alliance's detergent, "1/4 cup of mild detergent (including mild laundry detergents, car washing soap or dish soap) per gallon of water," is a metal-only recipe, and its rinse follows that recipe's own 5 to 10 minute stand, not ARMA's 15 to 20 minutes for shingle.

The water temperature of a rinse is its own question, covered on whether soft washing uses hot water. Where that water goes once it leaves the roof is what runoff names, and whether a roof is washed while its gutters are already full is answered on roof cleaning with full gutters.