3.4.6.7.

(1) Except as permitted for dwelling units and by Sentence 3.4.7.5.(1) for fire escapes, steps for stairs shall have a run of not less than 255 mm and not more than 355 mm between successive steps.

(2) Steps for stairs referred to in Sentence (1) shall have a rise between successive treads not less than 125 mm and not more than 200 mm.

(3) Treads and risers in every exit stair, except a fire escape stair, shall have uniform run and rise in any one flight, and shall not alter significantly in run and rise in successive flights in any stair system.

(4) Except as permitted by Sentence (6), the leading edge of a stair tread shall have either a radius or a bevel between 6 mm and 10 mm in horizontal dimension.

(5) The front edge of stair treads in exits and public access to exits shall be at right angles to the direction of exit travel.

(6) If resilient material is used to cover the leading edge of a stair tread, the minimum radius or bevel required by Sentence (4) is permitted to be reduced to 3 mm.