Staircase Guardrail Height Requirements Ontario 2026: OBC Part 9 Guide
Guardrail height requirements in Ontario are among the most frequently misquoted OBC specifications we encounter at C.O.R.S. Homeowners and even some contractors cite 42 inches (1,067mm) as a universal minimum — that is not correct under OBC Part 9 for residential construction. The actual requirements vary by location within the staircase and are expressed in millimetres.
This guide covers the exact OBC Part 9 guardrail height requirements for Ontario residential staircases as of 2026, including where each measurement applies and which common installation mistakes trigger failed inspections.
OBC Guardrail Height Requirements Ontario — The Exact Measurements
Under OBC Part 9 (Section 9.8.8), guardrails must meet the following minimum heights:
| Location | Minimum Guard Height | Measured From |
|---|---|---|
| Along stairs (stairwell guard) | 900mm | Leading edge of tread nosing line |
| At landings / top of stairs | 1,070mm | Finished floor surface |
| Balcony / loft edge | 1,070mm | Finished floor surface |
The critical distinction: the guard along the stairs themselves is 900mm measured from the nosing line of the treads. The guard at the top landing and any second-floor balcony is 1,070mm measured from the finished floor. In practice, this means the guard height is higher at the top of the stairs than along them.
Guard Height on Stairs — How To Measure Correctly
OBC always measures guard height vertically, never perpendicular to the stringer. For a staircase guard:
- Identify the nosing line â the imaginary line connecting the leading edges of each tread
- Measure vertically upward from that line to the top of the guard system at the point of measurement
- For a glass panel guard, the measurement ends at the top of the glass panel edge
- For a baluster/post guard, the measurement ends at the top rail
- The 900mm minimum must be met at every point along the stairs — not just at the midpoint
Guardrail Height for Common Staircase Types in Ontario
Here is how the OBC guard height requirements apply to the most common staircase types C.O.R.S installs in Ontario:
| Staircase Type | Guard Height (Stairs) | Guard Height (Landing) | Notes |
|---|---|---|---|
| Floating mono-stringer stairs with glass railing | 900mm min | 1,070mm min | Glass panel top edge measured from nosing line |
| Open-riser stairs with steel balusters | 900mm min | 1,070mm min | Stair openings must pass 100mm sphere test |
| Closed-riser wood stairs | 900mm min | 1,070mm min | Balusters at <100mm centre-to-centre |
| Spiral staircase | 900mm min | 1,070mm min | Measured from outer nosing line of spiral treads |
OBC Opening Requirements for Guardrails
OBC Part 9 requires that no opening in a guard system permit the passage of a 100mm sphere. This applies to:
- Baluster spacing: no spacing exceeding 100mm centre-to-centre
- Cable railing: each typically requires cables at 100mm centre-toch typically requires cables at 100mm centre-to-centre or closer
- Glass-to-glass joints: the gap between adjacent panels must not exceed 100mm
- Open riser stairs: the opening between treads above 600mm floor level must not permit passage of a 100mm sphere — this is why open riser staircases have a maximum riser opening
OBC Guardrail Height — Frequently Asked Questions
Stair railing height Ontario — what is the minimum?
The minimum stair guard height in Ontario is 900mm along the stairs, measured vertically from the leading edge of each stair tread nosing. This is lower than the 1,070mm minimum that applies at stair landings and balconies.
Guardrail height requirements Ontario — does it change for glass railing?
No â the same OBC height requirements apply regardless of material. Glass railing must meet 900mm along stairs and 1,070mm at landings. The difference is how the height is measured: for glass railing, it is taken to the top of the glass panel edge or the graspable rail if a nom-graspable glass edge is used.
What is the OBC guard height for a deck or balcony in Ontario?
For a deck or balcony attached to a residential building in Ontario, the minimum guard height is 1,070mm measured from the finished deck surface. This applies to decks more than 600mm above grade.
Guardrail height for an interior balcony or loft edge?
The minimum guard height for an interior balcony or loft edge in a residential building is 1,070mm measured from the finished floor surface. The 900mm minimum applies exclusively to the portion of the guard along the stairs themselves — not at landings or lofts.
OBC handrail height vs guardrail height — what is the difference?
Handrail height (865â965mm) and guardrail height (900mm on stairs, 1,070mm at landings) are two separate OBC requirements. The handrail is what you grasp — it must be graspable and within a specific height range. The guard is what prevents a fall — it must be a minimum height and resist specified lateral loads. A single railing system frequently satisfies both requirements simultaneously when properly designed.
Related Resources
- Handrail height requirements Ontario â measurement and graspability requirements
- Staircase landing requirements Ontario â when a landing is required and how large it must be
- Frameless vs semi-frameless glass railing Ontario â system selection with OBC-relevant comparisons
- Glass railing cost comparison Ontario â pricing for all system types