Can windows be cleaned when it is windy?

Picture the procedure already under way. The order runs from the top of the building down, the upper glass is finished, and solution is about to go on the next pane with a clean one right beside it. NGA's paper does not place its wind line at a particular step; a moment like this one, clean glass beside fresh solution, is simply where it applies. The line reads: “Cleaning procedures should also include checking that the wind is not blowing the cleaning solution and residue onto already cleaned glass.”

The top-down order came first, and it exists for a related reason. NGA Glass Technical Paper FB01-00 says exterior cleaning should begin at the top of the building and continue to the lower levels “to reduce the risk of leaving residue and cleaning solution on glass that has already been cleaned.” Runoff falls, so working downward keeps it on glass that still has to be done.

Wind does not follow that order. It can carry solution sideways onto the pane that was just finished, or lift it back onto glass above. Read side by side, the two lines divide the work: the order handles what runs down, and the check handles what blows across.

Notice what the line is not. It is a check, not a ban, and it comes with no number. None of the glass documents cited here names a wind speed at which glass cleaning stops, and this page supplies none. What the check asks is a question with a visible answer: is solution landing where the work is already done?

The wind check protects a rule that runs through the whole routine method. Among NGA's own DO NOT items: “DO NOT allow water or cleaning residue to remain on the glass or adjacent materials.”

In the routine method, NGA has a window cleaning squeegee remove all of the cleaning solution from the glass immediately after it is applied. A pane that has been squeegeed and then catches a gust of solution from its neighbor is holding residue again, which is what that DO NOT item forbids. Left there, it dries on glass that was already finished, and residue drying on clean glass is how streaking gets onto a pane that was done.

The pure water technique ends differently. NGA describes gentle agitation with a non-scratching brush and a final pure water rinse that is generally allowed to evaporate from the glass. Anything a gust carries onto that pane after its last rinse dries along with it, so the same question about wind applies at the end of that method as well.

Wind is only one kind of weather that puts water where it should not be. Rain raises its own questions about what dries on glass, and those are taken up in whether windows can be cleaned in the rain. Spray drifting onto windows from work on a roof is a separate problem again, covered under overspray.

Coastal wind has a definition in the weather service's glossary. The National Weather Service describes a sea breeze as “A thermally produced wind blowing during the day from a cool ocean surface onto the adjoining warm land,” caused by the difference in how quickly the ocean and the land heat up. The definition names no place and no speed, and nothing here turns it into a forecast for Naples.

What coastal wind carries onto glass, as distinct from what it does during a cleaning, is a subject of its own. Salt spray and the reasons windows get dirty fast near the beach are argued there. This page stays with the procedure.

Reach equipment raises a wind question too, and the answer is the same kind of silence. No document cited here sets a wind speed at which a pole or a ladder has to come down. The ladder rules that are published are gathered in whether window cleaners use ladders.

The glass procedure itself, from the first soak to the squeegee, is laid out as the published window cleaning method on the window cleaning page. NGA's wind check is one line in the paper behind that method, and a useful one to know: when you watch glass being cleaned on a windy afternoon, the question the standard asks is whether solution is landing on panes already done.