CSLB General Building (B)Framing and CarpentryMedium
A contractor frames a stairway with tread depths (run) of exactly 10 inches, the code minimum. To help compensate, the treads are given a nosing that projects beyond the riser below. What is the required nosing projection range for treads with less than 11 inches of run?
- ANo nosing is required if the tread meets minimum run
- B3/4 inch to 1-1/4 inches
- C1-1/2 inches to 2 inches
- D1/4 inch to 1/2 inch
Show answer & explanationAnswer & explanation
Correct answer: B. 3/4 inch to 1-1/4 inches
When a stair tread's run is less than 11 inches, the code requires a nosing that projects between 3/4 inch and 1-1/4 inches beyond the face of the riser below, effectively increasing the usable foot placement area. This projection helps maintain safe footing on shallower treads.
Why the other options are wrong
- A. Nosing is specifically required because the run is below 11 inches.
- C. Exceeds the maximum allowed nosing projection.
- D. Too small a projection to meet the code minimum.
Stair Nosing Projection
For stair treads with a run less than 11 inches, a nosing projecting 3/4 to 1-1/4 inches beyond the riser face is required to improve foot clearance.
- Applies when tread run < 11 inches
- Nosing range: 3/4 in to 1-1/4 in
- Nosing profile radius also regulated (max 9/16 in)
Memory trick: Three-quarter to one-and-a-quarter, give your toe some quarter.