The Ontario Building Code | Stairs
(1) Stairs shall be inclined at an angle of not more than 45° with the horizontal, and their steps shall have risers not more than 210 mm high and treads not less than 220 mm wide exclusive of nosing.
(2) Stairway headroom shall be not less than 1 950 mm plus the height of one riser measured vertically above the nosing of any tread or platform.
(3) The width of a fire escape shall conform to Articles 184.108.40.206., 220.127.116.11. and 18.104.22.168., except that the width is permitted to be reduced to 550 mm provided the fire escape serves,
(a) not more than 3 storeys, and
(b) not more than 15 persons.
(4) If a flight of stairs leading to the ground at the foot of a fire escape is not fixed in position, it shall,
(a) be held in the raised position without a latch or locking device,
(b) be fitted with a counterbalancing device,
(c) be easily and quickly brought into position for use, and
(d) reach the ground in the lowered position.