Stairway risers and treads: acceptable and preferred dimensions.

Stairway preference and acceptability were investigated with psychophysical techniques. A series of six experiments was conducted where subjects ascended and descended 19 sets of stairways with different riser and tread (run) dimensions. Subjects were instructed to identify stairways that they considered acceptable, and the one stairway they most preferred. The optimum riser was 7.2 in (183 mm), and the optimum tread (run) was 11 or 12 in (279 or 300 mm). These dimensions were acceptable to both males and females, young and old, and subjects of greater or lesser stature. Larger dimensions were not as acceptable to shorter subjects, and smaller dimensions were not as acceptable to taller subjects. The 4-in (102 mm) riser was almost totally unacceptable, and never preferred. The 5.14 and 9-in (131 and 229 mm) risers were acceptable to less than one-third of the subjects, and rarely or never preferred. These results are compared with existing practices and recommendations.