Figure 30(c) Rear Wall of Standard Stall. Grab bars located behind the water closet shall be at least 36 inches (915 mm) in length. One end of the grab bar is shown near the corner of the stall closest to the water closet. Figure 30(a) shows this end 6 inches (150 mm) maximum from the corner. All grab bars shall be located 33-36 inches (840-915 mm) above the finish floor.