2010 ADA Standards for Accessible Design Pocket Guide

505.10.3 Bottom Extension at Stairs.

At the bottom of a stair flight, handrails shall extend at the slope of the stair flight for a horizontal distance at least equal to one tread depth beyond the last riser nosing. Extension shall return to a wall, guard, or the landing surface, or shall be continuous to the handrail of an adjacent stair flight.

Figure 505.10.3 Bottom Handrail Extension at Stairs