Question

What is the standard height of a riser in a residential building's staircase according to typical building codes?

• A. 50–75 mm
• B. 100–125 mm
• C. 150–175 mm
• D. 200–225 mm

Hint:

A comfortable stair follows the rule: $2 \times \text{Riser} + \text{Tread} \approx 600$ mm.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Ergonomics and safety codes determine the dimensions of stairs to ensure comfortable climbing and descent.
Step 2: Detailed Explanation:
A "riser" is the vertical height between two consecutive steps.
Standard residential codes (like NBC India) recommend a riser height between 150 mm and 175 mm.
Risers higher than 175 mm are considered too steep for general comfort, while those below 150 mm are usually reserved for public buildings or elderly access.
Step 3: Final Answer:
The standard height is 150–175 mm.