Ontario Building Code: Indoor Stair & Railing Requirements
The Ontario Building Code sets specific rules for indoor stair rise, run, headroom, and handrail and guard dimensions. These figures come from OBC Section 9.8, checked against the current 2024 Building Code (O.Reg. 163/24), and are here as a general reference — requirements depend on the specific project and your local building authority.
Last checked against current official sources: . This page is a general reference, not legal advice — requirements depend on the specific project and your local building authority.
Rise and run
For private stairs within a home, OBC Tables 9.8.4.1–9.8.4.2 set rise (step height) between 125 mm and 200 mm, and run (step depth) between 255 mm and 355 mm, both measured nosing to nosing. This range exists so steps feel consistent and predictable to walk, and it's one of the first things we calculate when designing a new staircase.
Headroom clearance
OBC Section 9.8.2.2 sets minimum headroom over a stair at 1,950 mm (about 6 feet 5 inches), measured vertically from the front edge (nosing) of each tread to the ceiling or lowest obstruction above. This is frequently the limiting factor on new basement staircases, since floor-to-floor height in a given home is fixed.
Handrail height
OBC Section 9.8.7.3 requires handrails between 865 mm and 965 mm above the stair nosing. This range, not a single number, is why we confirm the specific target height during design rather than build to a rounded-off figure.
Guard height and when a guard is required
OBC Section 9.8.8.1 sets a minimum guard height of 900 mm on interior floors, mezzanines and balconies. A guard is required on any interior stair with more than two risers, on the open side(s) not already protected by a wall.
Guard opening (spindle spacing)
OBC Section 9.8.8.5 requires that no opening in a guard allow a 100 mm sphere to pass through — in practical terms, the gap between spindles or balusters can't exceed 100 mm. This is the rule most commonly out of compliance on older homes we assess, where spindle spacing was set to an older, wider standard. The 2024 Building Code added a specific sentence for the triangular gap formed by a tread, riser and the bottom rail of a guard on a stair: that opening only needs to block a 150 mm sphere, not 100 mm, since its shape and location make it lower-risk than a vertical opening between spindles.
Open risers
Open-riser stairs (no solid riser board, so you can see through each step) are a popular look, but the 2024 Building Code restricts them in Part 9 buildings: they're only permitted on stairs serving a single dwelling unit or a house with a secondary suite, fire escape stairs, maintenance stairs, stairs serving service rooms, and stairs serving certain industrial occupancies. If an open-riser design is on the table for your project, we'll flag whether it's actually permitted for your specific stair before you commit to the look.
Frequently asked questions
Are these figures still current?
Yes — this page was checked directly against the current Ontario Building Code (the 2024 edition, O.Reg. 163/24, in effect since January 1, 2025) as of the date shown above, not just carried over from an earlier version. That said, the Code is periodically amended and interpretation can vary by municipality, so always confirm current requirements with your local building department for your specific project rather than relying solely on this page.
Do these rules apply to a renovation, or only new construction?
Rise, run, headroom, handrail and guard requirements generally apply whenever you're building a new staircase or making a structural change to an existing one. A cosmetic renovation that keeps the existing structure and dimensions unchanged is less likely to trigger a full code review, but any structural change should be checked against current requirements.
What happens if my existing stairs don't meet current code?
Many older homes have staircases built to an earlier code version and are generally allowed to remain as-is under existing-building provisions, as long as you're not doing a renovation that specifically triggers an upgrade requirement. We'll flag anything we find that's worth addressing regardless, especially spindle spacing, since it's a real safety issue independent of what triggered the renovation.
Who do I actually ask if I'm not sure whether my project needs a permit?
Your local municipal building department is the authoritative source for whether a specific project needs a permit — we'll flag it directly if we believe yours does, but the final determination is theirs, not ours.
Does this guide cover exterior stairs or decks?
No — we work on indoor stairs only, and this guide is scoped to the interior stair provisions of OBC Section 9.8. Exterior stairs and decks have their own related but distinct code requirements.