Does a roof get rinsed after soft washing?

ARMA's second bulletin gives the shingle method in one line: apply with a sprayer, dwell 15 to 20 minutes, then rinse thoroughly with low pressure water. The next sentence is the reason the rinse is not a courtesy step: extended dwell times may be necessary, the bulletin says, but "avoid letting the solution dry completely as this may prevent complete rinsing." A solution that dries completely may not come off completely with water, which is the case for rinsing while it is still wet.

The minutes themselves are a separate subject, answered on the roof cleaning page and defined at the dwell time entry linked below. What this page takes from the bulletin is the order: apply, wait, and rinse before the solution dries.

Every published procedure read for this page ends in a rinse, and each one is written for its own material. ARMA's technical bulletin on algae discoloration puts it plainly: "Finally, rinse the solution from the roof by gently spraying the surface with water." GAF's current bulletin for its own shingles applies its mixture with a garden sprayer, leaves it up to 20 minutes, and rinses with low-pressure water, with shrubs below protected.

The Metal Roofing Alliance publishes a different chemistry and a different rinse in the same breath: its mild detergent solution stands 5 to 10 minutes before the surface is rinsed thoroughly with plain water. No roofing maker or association read for this page names a water temperature; ARMA says water, GAF says low-pressure water, the Metal Roofing Alliance says plain water. Three documents, two materials, and the same last step in each: a rinse.

ARMA's second bulletin also describes what happens after the treatment is finished: algae will disappear and wash away with subsequent rains, moss loosens over time, and in severe cases it may take more than one bleach treatment to kill all of the moss. That sentence is about dead algae after the work is done, not a description of the rinse step itself, and it is never written as a substitute for it.

Whether rain right after a treatment changes anything about that day's schedule is answered on the roof cleaning page rather than here, and whether a job can proceed while it is raining has its own page. The point here is narrower: the published procedures all close with a rinse step.

The rinse instruction for a given roof is that roof's maker's, and this page prints no rinse pressure of its own. Water temperature is answered at soft wash and hot water, and the apply, dwell, rinse sequence the trade publishes is laid out in full at how a soft wash proceeds.

Two related words are worth knowing on their own terms. The rinse step itself, what the trade calls a rinse-down, and the minutes a solution sits before it, dwell time, are each defined at length rather than repeated here. Where the rinse water goes once it leaves the roof is a separate question, answered at roof cleaning runoff.