The most common question, and the most commonly misunderstood answer. Area is one factor, and usually not the largest.
The access method
The difference between an elevation a truck can park in front of and one only a rope reaches is the single biggest variable in any proposal. The first is done faster with fewer people; the second needs rigging, a trained crew and time.
The shape of the elevation
A flat wall is roughly twice as fast as one with projections, recesses and balconies. Every break in the surface means repositioning, and repositioning is what consumes the time rather than the washing.
The surface
Glass is the fastest. Porous stone and metal mesh are slower, need different products, and sometimes two passes.
The condition it is in now
An elevation that has not been cleaned in years is not slightly more expensive, it needs a whole additional stage before the normal wash. The first clean after long neglect is always the dearest, and everything after it is far cheaper.
Timing
Nights and weekends add operating cost: lighting, coordination, and hours outside the working day. Sometimes that is worth it and sometimes it is not.
What gets cleared, and for how long
Closing parking or a walkway for several days has a cost to the building itself rather than to the proposal. It belongs in the schedule conversation, not after it.
Why there is no price on this page
Because any number published before seeing the elevation will be wrong for one of us. The survey costs nothing and the number follows it, built on the above rather than on an average.