A carpenter is constructing a staircase with a total rise of 2400 mm and a desired riser height of approximately 185 mm. According to the National Building Code of Canada, what is an acceptable number of risers and their height?

Question: A carpenter is constructing a staircase with a total rise of 2400 mm and a desired riser height of approximately 185 mm. According to the National Building Code of Canada, what is an acceptable number of risers and their height?

Answer options:

• 12 risers at 200 mm each
• 13 risers at 184.6 mm each ✅ 14 risers at 171.4 mm each
• 15 risers at 160 mm each

Correct answer: 14 risers at 171.4 mm each

Explanation: To determine the number of risers, divide the total rise by the desired riser height (2400 mm / 185 mm ≈ 12.97). Rounding up or down (in this case, rounding up to 14 risers) and recalculating (2400 mm / 14 = 171.4 mm per riser) falls within the NBC specifications for maximum and minimum riser heights (typically 125 mm to 200 mm and consistent to within 5 mm). 13 risers at 184.6mm would also be acceptable.