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

Concept: In staircase design, the riser is the vertical portion between two consecutive steps. Its height is crucial for safety, comfort, and ease of movement.
Step 1: Understand ergonomic considerations.
The riser height must:

• Allow comfortable climbing
• Prevent fatigue
• Ensure safety, especially for children and elderly users

Step 2: Standard dimensions.
Typical building codes recommend:

• Riser height: 150–175 mm
• Tread depth: 250–300 mm

Step 3: Analyze the options.

• 50–75 mm – too low
• 100–125 mm – below standard
• 150–175 mm – correct standard range
• 200–225 mm – too steep and unsafe

Step 4: Conclusion.
Thus, the standard riser height is 150–175 mm.