Whoever uses ladders to clean 4th story windows has some big ones! I would be terrified to be on a ladder that high. Do you you fiberglass ladders? I find the aluminum ones pretty shaky when you start getting up high. I, personally, would look into how it cost for renting a scissor lift. It seems like a much safer way to clean windows. I, myself, primarily do residential windows so I only need to clean windows 2 stories up most of the time. If I was cleaning 4th story windows regularly, I would look into getting a water-fed pole system. It would probably pay for itself pretty quickly.
Bainbridge Island Window Cleaning