Residential Building Inspector B1Public Safety and Special ConstructionMedium
An inspector is evaluating a stairway that serves as the primary egress from a dwelling unit. What is the maximum allowable riser height for any step in this stairway?
- A7 3/4 inches
- B8 inches
- C7 inches
- D7 1/4 inches
Show answer & explanationAnswer & explanation
Correct answer: A. 7 3/4 inches
IRC R311.7.5.1 states that the maximum riser height shall be 7 3/4 inches. The riser height shall be measured vertically between the leading edges of adjacent treads.
Why the other options are wrong
- B. This height exceeds the maximum allowed by the IRC for residential stairs.
- C. This is a common maximum for commercial stairs or specific residential designs, but not the IRC maximum.
- D. This is often mistaken as the maximum, but the IRC allows slightly more.
Stair Riser Height Limit
The maximum height of a stair riser is regulated to ensure safe and comfortable ascent and descent. The IRC specifies a maximum for residential applications.
- Applies to all steps in a stairway.
- Measured vertically from leading edge to leading edge.
- Maximum 7 3/4 inches in residential buildings.
Memory trick: Riser's seven and three-quarters, a safe height for all sons and daughters.