Stair design guideline — maximum recommended pitch (slope) of a stair What is the usual maximum pitch (angle to the horizontal) recommended for stairs in buildings to ensure comfortable and safe movement?

Introduction / Context:Stair pitch is a key ergonomic factor affecting safety and comfort. Excessive steepness leads to fatigue and accident risk; too shallow a slope is space-inefficient. Building practice therefore limits the pitch within a preferred range and sets a clear maximum for general occupancy stairs.

Given Data / Assumptions:

• Ordinary buildings, not ladders or industrial stairs.
• Riser and going satisfy comfort rules (e.g., 2r + g ≈ 600–650 mm).
• Uniform treads and risers across the flight.

Concept / Approach:Many codes and standards recommend a preferred pitch between roughly 25° and 40°, with 40° commonly cited as an upper limit for regular stairs. Within this range, normal riser/going proportions yield a comfortable stride and acceptable footprint, balancing safety and layout constraints.

Step-by-Step Solution:

Verification / Alternative check:Example: riser = 170 mm, going = 260 mm gives pitch ≈ arctan(170/260) ≈ 33°, within the preferred range and well below 40°.

Why Other Options Are Wrong:

• 25°, 30°: allowable but not the maximum; these are typical comfortable pitches.
• 50°, 60°: too steep for building stairs; unsafe for normal use.

Common Pitfalls:Inconsistent risers/goings causing trip hazards; ignoring headroom and landing requirements.

Final Answer:40°