Framing & StructuralQuestion 451 of 700
A residential stairway must rise a total of 105 inches from finished floor to finished floor. Using the maximum allowable riser height of 7-3/4 inches, what is the MINIMUM number of risers, and the resulting even riser height?
a.13 risers at about 8.08 inches each
b.13 risers at about 7.75 inches each
c.14 risers at 7.5 inches each
d.12 risers at about 8.75 inches each
Explanation
Divide 105 by the 7.75-inch maximum: 105 / 7.75 = 13.5, which rounds up to 14 risers because you cannot exceed the maximum. 105 / 14 = 7.5 inches per riser, within the limit. Thirteen risers would each be about 8.08 inches, exceeding the 7.75-inch cap; twelve risers at 8.75 inches also exceed the maximum.
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