1. Except as provided in Article 9.8.4.7. and except for stairs serving areas only used as service rooms or service spaces, the rise, which is measured as the vertical nosing-to-nosing distance, shall comply with Table 9.8.4.1.

Table 9.8.4.1.
Rise for Rectangular Treads, Tapered Treads and Winders
Forming Part of Sentence 9.8.4.1.(1)

Notes to Table 9.8.4.1.:
(1) Private stairs are exterior and interior stairs that serve
(a) single dwelling units,
(b) houses with a secondary suite including their common spaces, or
(c) garages that serve a) or b).
(2) Public stairs are all stairs not described as service stairs or private stairs.

1. Except for stairs serving areas only used as service rooms or service spaces, the run shall comply with Table 9.8.4.2.

   Table 9.8.4.2.
   Run for Rectangular Treads
   Forming Part of Sentence 9.8.4.2.(1)

   

   Notes to Table 9.8.4.2.:
   (1) Private stairs are exterior and interior stairs that serve
   (a) single dwelling units,
   (b) houses with a secondary suite including their common spaces, or
   (c) garages that serve a) or b).
   (2) Public stairs are all stairs not described as service stairs or private stairs.

2. The depth of a rectangular tread shall be not less than its run and not more than its run plus 25 mm.

1. Except as provided in Sentence (2) and Articles 9.8.4.6. and 9.8.4.7., tapered treads shall have a run that
   1. is not less than 150 mm at the narrow end of the tread, and
   2. complies with the dimensions stated in Table 9.8.4.2. when measured at a point 300 mm from the centre line of the handrail at the narrow end of the tread.
2. Tapered treads in required exit stairs shall conform to the requirements in Article 3.4.6.9.
3. The depth of a tapered tread shall be not less than its run at any point and not more than its run at any point plus 25 mm.

1. Except as provided in Sentence (2), risers shall be of uniform height in any one flight, with a maximum tolerance of
   1. 5 mm between adjacent treads or landings, and
   2. 10 mm between the tallest and shortest risers in a flight.
2. Except for required exit stairs, where the top or bottom riser in a stair adjoins a sloping finished walking surface, such as a garage floor, driveway or sidewalk, the height of the riser across the stair shall vary by not more than 1 in 12.
3. Rectangular treads shall have a uniform run with a maximum tolerance of
   1. 5 mm between adjacent treads, and
   2. 10 mm between the deepest and shallowest treads in a flight.
4. Tapered treads in a flight shall have a uniform run in accordance with the construction tolerances stipulated in Sentence (3) when measured at a point 300 mm from the centre line of the handrail as described in Sentence 9.8.7.1.(5).
5. The slope of treads shall not exceed 1 in 50.

1. Except as provided in Sentence (2) and Article 9.8.4.6., where a flight of stairs consists of both tapered treads and rectangular treads, all the treads shall have a uniform run when measured at a point 300 mm from the centre line of the inside handrail.
2. Where tapered treads are located at the bottom of a mixed-tread flight, the run of the tapered treads when measured at a point 300 mm from the centre line of the inside handrail is permitted to exceed the run of the rectangular treads.

1. Individual treads in winders that converge on a centre point shall turn through an angle of
   1. 30° with no deviation above or below 30°, or
   2. 45° with no deviation above or below 45°.
2. Where winders are incorporated into a stair, each set shall not turn through more than 90°.

1. Spiral stairs shall have
   1. handrails on both sides, the outer handrail being not less than 1 070 mm high,
   2. a clear width not less than 660 mm between the handrails,
   3. risers that are not more than 240 mm high,
   4. treads that
      1. are a minimum of 190 mm deep at a point 300 mm from the centre line of the handrails at the narrower edge,
      2. have a consistent angle and uniform dimension, and
      3. turn in the same direction, and
   5. not less than 1 980 mm clear height.
2. Spiral stairs conforming to Sentence (1) are permitted to be used as the only means of egress where they serve not more than 3 persons.
3. Spiral stairs shall not serve as an exit.

1. Except as permitted by Sentence (2), the top of the nosings of stair treads shall have a rounded or beveled edge extending not less than 6 mm and not more than 14 mm measured horizontally from the front of the nosing.
2. If resilient material is used to cover the nosing of a stair tread, the minimum extension of the rounded or beveled edge required by Sentence (1) is permitted to be reduced to 3 mm.