Putzbalkone II

As a follow-up to a comment to one of my recent entries, I took another look at Putzbalkon and found this definition:

Putzbalkone dienen der Wartung von Außenfassaden, die überwiegend aus Glas bestehen.

The client also seemed certain that Putz- refers to cleaning, not plaster, and I am not sure whether plaster is used on external surfaces anyway -- it does not seem to be a very water-resistant material, though I may not be familiar with some common construction component.