What is the least acceptable width for a stair intended for an occupant load of less than 10?

For a stair intended for an occupant load of fewer than 10 people, the least acceptable width is generally established in building codes to ensure safety and accessibility. The correct answer is 700 mm, which is a standard measurement that balances the need for sufficient space for safe egress while accommodating the number of users anticipated.

In practice, building codes are often designed to promote the safe movement of occupants, allowing for individuals to ascend or descend without congestion, particularly during emergencies. A width of 700 mm is considered the minimum that provides a practical and safe allowance for people to use the stairway comfortably. It ensures that two individuals can pass each other safely and conforms to recommendations for width in light of maintaining safe egress.

Wider stair dimensions may be recommended for higher occupant loads or in specific building types (like assembly buildings), but for an occupant load of fewer than 10, the 700 mm standard is both effective and practical.