Angled treads in winders in stairs within dwelling units, for buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

This also applies to stairs within dwelling units in buildings to which Part 3 applies [see Sentence 1.3.3.2.(1) of Division A for application of Part 3], as stated in Sentence 3.3.4.7.(1).

To limit the probability that a mismatch between winder configuration and the natural gait of most users will lead to:

• persons misstepping and falling, or
• persons misstepping and falling in an emergency, which could lead to delays in the evacuation or movement of persons to a safe place.

This is to limit the probability of harm to persons.

To modify the application of Sentence 9.8.4.4.(2) for uniformity of treads in stairs within dwelling units where the occupant load is low and occupants are likely to be familiar with their surroundings, on the basis that a specific stair configuration has traditionally been used extensively within dwelling units without dramatic consequences for the safety of persons and that experience warrants its continued use.