Figure 18. Usable Tread Width and Examples of Acceptable Nosings.
Figure 18(a) Flush Riser. Each stair tread is 11 inches (280 mm) deep minimum with a sloped riser. The nosing shall project no more than 1-1/2 inches (38 mm).
Figure 18(b) Angled Nosing. An angled nosing may be used with a 60 degree angle measured from horizontal. The nosing shall project no more than 1-1/2 inches (38 mm).
Figure 18(c) Rounded Nosing. A rounded nosing may be used with a 60 degree angle measured from horizontal. The nosing shall project no more than 1-1/2 inches (38 mm).