For the included figure, which dimension is the tread depth?

Exhibit.

For the included figure, which dimension is the tread depth?
A . A
B . B
C . C
D . A+B

View Answer

Answer: B

Explanation:

The tread depth is the horizontal distance from the front edge of a stair tread to the back edge of the same tread, which corresponds to dimension "B" in the figure. According to NFPA 101, Life Safety Code, the tread depth is crucial in ensuring safe stairway design for proper footing and egress.