Patent ID: 7972446

Claim:
A method for cleaning a generally vertically extending exterior surface of a building characterized by: providing a housing to permit cleaning of a generally vertically extending exterior surface of a building while minimizing movement of the housing away from the building during cleaning of the exterior surface, locating at least one cleaning element with outwardly extending cleaning vanes on the housing for rotation about a generally horizontal axis for cleaning the exterior surface of the building, rotating the cleaning element with a first motor disposed on the housing, dispensing a cleaning liquid from applicators mounted on the housing toward the exterior surface adjacent the cleaning element, during cleaning of said surface, pendently supporting the housing and cleaning element adjacent the exterior surfaced of the building, moving the housing and cleaning element with a second motor disposed on the housing relative to the generally vertically extending exterior surface of the building to clean the exterior surface of the building with the cleaning element, establishing with a counterforce system a continuous substantially perpendicular force on the housing and cleaning element towards the generally vertically extending exterior surface of the building to maintain the cleaning vanes in surface cleaning engagement with said vertically extending exterior surface during cleaning thereof.