Pre-wetting

ICPI's Tech Spec 5 gives the mechanism in one instruction, written for paver work: "When using strong acidic stain removers or cleaners that might drain onto vegetation, saturate the vegetation with water prior to using acidic cleaners." ICPI's own reason follows in the next sentence: doing so "will minimize absorption of cleaner rinse water and reduce risk of damage to vegetation."

The order is the whole instruction: water on the plant first, the acidic cleaner second, and ICPI's sentence opens with its own condition, strong acidic cleaners that might drain onto vegetation. The rest of ICPI's ground-level list, and how it sits beside a roof wash, is laid out on the soft washing method page, around the roof. The same document's word for solution carried onto nearby branches and shrubs, overspray, has its own entry.

A roof job's own documents carry a precaution rather than ICPI's saturate-first mechanism. ARMA tells the person applying a shingle solution to "apply it carefully to avoid damage to other parts of the building and the surrounding landscape," and GAF's own instruction for its mixture is shorter still: "Be sure to protect any shrubs below."

Neither of those lines is ICPI's mechanism, and neither says how the protecting is done. None of the three documents, ARMA's, GAF's or ICPI's, publishes a step that neutralizes a plant or the soil once the work is over; the word "neutralize" is in none of them. Whether a roof wash harms the plants in a Naples yard is answered on whether roof cleaning hurts plants.

Two roof-side questions sit next to this one and have their own answers: keeping pets inside during roof cleaning and roof cleaning with full gutters. Whether a cleaner is phosphate-free is a separate chemistry question from how nearby plants are protected, with an entry of its own.