Can second-story windows be cleaned from the ground?

Start at the glass, not at the ground. The routine method the National Glass Association (NGA) publishes has one step that brings a tool, and the hand holding it, to the pane.

NGA's routine opens with a soak of clean water and a mild, non-abrasive solution, applied with a brush, strip washer or other non-abrasive applicator and lightly agitated. The step after it is the one that matters here: immediately after the solution goes on, a window cleaning squeegee is used “to remove all of the cleaning solution from the glass surface.”

By the Cambridge Dictionary's definition, a squeegee has a short handle. A short handle keeps the hand near the glass, which is why, in the routine method, the squeegee step is the one that needs someone at the pane.

NGA's paper records a second technique: the International Window Cleaning Association (IWCA), it says, recognizes an additional technique used by some professional window cleaning contractors, in which pure water is delivered to the glass with a specialized extension pole. On the glass, gentle agitation with a non-scratching, non-abrasive brush is followed by a final pure water rinse, and the rinse water is “generally allowed to evaporate from freshly cleaned surfaces.”

Read the steps in that description and the squeegee is gone. Water arrives through the pole, a brush on the end of it does the agitating, and the rinse is left on the glass to dry. Nothing in that sequence needs a hand at the pane, which is the reason upper glass can be worked from the ground. That is a reading of NGA's description, not a sentence NGA wrote.

The tool fits the description. A maker, Unger, describes its water-fed poles as a way to “clean upper-story windows from ground level.” The parts of the system are laid out under what a water-fed pole is, and the method in context under pure water and the water-fed pole.

Leaving the rinse to dry has a condition attached, and NGA states it in the next sentence: because the rinse is left to evaporate, the water used for both the wash and the rinse must have 20 parts per million (PPM) or less of total dissolved solids, TDS, to prevent spotting and streaking, and tap water is not acceptable.

That is the trade the pole makes. The squeegee no longer carries the water off the glass, so the water itself has to be pure water, treated to meet that limit.

Why a treated rinse can dry on glass without spotting is explained under why pure water dries without spots.

Moving the cleaner to the ground does not move the rest of the procedure. NGA's exterior order still holds: work starts at the top of the building and continues to the lower levels, so residue and solution are not left on glass that is already clean. Its test area still comes first, a small area of one window cleaned and examined before the project proceeds. And where film has been applied to the outside of a pane, NGA's film rules against bristle brushes and abrasive materials still apply to whatever touches it.

The pole is not the only way to reach upper glass. A ladder puts a person up at the pane, and the published rules for a ladder set against a house are covered under whether window cleaners use ladders. What a neighbor sees when glass is left wet after a pole rinse is taken up under why a window cleaner sprays from the ground.