Nosing Projection (Overlap)

The nosing projection is the horizontal distance from the front edge of a tread to the rear edge of the tread surface below. It is not counted towards the going but visually enlarges the usable tread area. For open stairs, DIN 18065 requires a nosing projection of at least 30 mm; for closed stairs, a going of less than 260 mm may be compensated by a corresponding nosing projection.