276 Chapter 11
The stairways should provide accessibility between building floors; when these stairs are not con-
nected by an elevator, they must be designed according to certain standards specifying the configura-
tion of treads, risers, nosings, and handrails. The maximum riser height is 7 inches (178 mm), and the
treads must be a minimum of 11 inches (280 mm) as measured from riser to riser. Open risers are not
permitted. The undersides of the nosings must not be abrupt and must conform to one of the styles
shown in Figure 11.12. Stairway users are more likely to stumble or fall while going down stairs than
when going up. Tread depth is pivotal in stair design. Typically when climbing a stairs, users place only
part of their foot on the tread, whereas when descending the whole foot or most of the foot is placed on
the tread.
Figure 11.11 New and current handrail requirements for ramps and stairs (sources: Gerald J. Morgan; 28
CFR Ch.1, Pt. 36, App.A, Fig.39, 7-1-94 Edition).