The Ontario Building Code | Minimum Number of Risers
3.4.6.2. Minimum Number of Risers
(1) Except as permitted by Sentence 3.3.2.13.(1), every flight of interior stairs shall have no fewer than 3 risers.
In Plain Language
Every flight of interior stairs must have at least 3 risers, since a shorter run of one or two steps is easy to miss and trip over, especially during an emergency evacuation.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.