Ontario Building Code: Stairs & Guards

Ontario doesn’t use the National Building Code directly — it runs its own Ontario Building Code (OBC), currently the 2024 edition (O. Reg. 163/24), in force since 1 January 2025. The OBC adopts the NBC 2020 as its model and layers Ontario amendments on top (it runs to some 800 pages).

For a house stair, the Part 9 (Section 9.8) figures match the NBC 2020 baseline — 200 mm max riser, 255 mm min run, 1950 mm headroom, 860 mm min width, 900 mm guards (1070 mm otherwise), the 600 mm guarding trigger and the 100 mm gap. See the Canada stair & guard rules for the full set, and confirm any figure against the official 2024 Building Code Compendium before you build.