The Ontario Building Code | Straight and Curved Runs in Stairs
9.8.3.1. Straight and Curved Runs in Stairs
(1) Except as provided in Sentence (2), stairs shall consist of,
(a) straight-runs, or
(b) curved-runs.
(2) Stairs within dwelling units shall consist of,
(a) straight-runs,
(b) curved-runs,
(c) straight-runs with winders, or
(d) straight-runs with curved-runs.