The Ontario Building Code | Platforms
(1) A tactile attention indicator conforming to Article 18.104.22.168. shall be installed along any edge of a platform that is,
(a) not protected by a guard, and
(b) higher than 250 mm above the finished floor or ground or sloped steeper than 1 in 3.
(2) Sentence (1) does not apply to the front edges of stages.