The Ontario Building Code | Stair Width
22.214.171.124. Stair Width
(1) Except as provided in Sentence (2), required exit stairs and public stairs serving buildings of residential occupancy shall have a width, measured between wall faces or guards, of not less than 900 mm.
(2) At least one stair between each floor level within a dwelling unit, and exterior stairs and required exitstairs serving a single dwelling unit, shall have a width of not less than 860 mm.
Note: On July 1, 2017, Sentence 126.96.36.199.(2) of Division B of the Regulation is amended by striking out "single dwelling unit" and substituting "houseor an individual dwelling unit". (See: O. Reg. 139/17, s. 75)
(3) Required exit stairs and public stairs serving buildings of other than residential occupancy shall have a width of not less than the greater of,
(a) 900 mm, or
(b) 8 mm per person based on the occupant load limits specified in Table 188.8.131.52.