The layout of the Hearst Tower is such that the facade is very jagged. Plans for a rig, designed by Tractel-Swingstage, to hold window cleaners, took 3 years and 3 million dollars because of the building's concave windows, referred to as "bird's mouths".[6] The resulting design incorporates "a rectangular steel box the size of a Smart car, supporting a 40-foot mast and hydraulic boom arm attached by six strands of wire rope to a telescopic cleaning basket, [and housing] a computer that monitors 67 electromechanical safety sensors and switches".[7] The device was installed in April 2005 on 420 feet of elevated steel track looping the roof of the tower.[7]
On June 12, 2013, two window cleaners were trapped on the window cleaning crane partway down from the top of the tower.[8] The unique zigzag grid on the building's exterior and "bird's mouth" divots on its corners necessitated development of a special scaffold for window washers.