How high a glass railing needs to be in Ontario
When a deck, balcony or stair needs a guard, how high it has to be, and what the Building Code asks of the glass.
Ontario’s Building Code calls a railing that keeps people from falling a guard. The rules here come from the 2024 Building Code, in force since January 1, 2025, mostly Article 9.8.8 for houses. This is a plain summary, not the Code itself, and your city’s building department has the final word.
When you need a guard
A deck, porch, balcony, landing, stair or ramp needs a guard on every open side where the surface within 1.2 m (3′ 11 1/4″) of it is more than 600 mm (23 5/8″) lower. A wall can take the place of a guard on that side.
Below 600 mm a guard isn’t required, though you can still add one.
How high it has to be
Height is measured from the walking surface up to the top of the guard.
| Where the guard is | Minimum height |
|---|---|
| Inside a house, including stairs | 900 mm (35 7/16″) |
| Outside a house, where the deck, porch, balcony or stair is no more than 1800 mm (5′ 10 7/8″) above the ground | 900 mm (35 7/16″) |
| Outside a house, more than 1800 mm above the ground | 1070 mm (42 1/8″) |
| Condo and apartment balconies, common areas, and most other buildings | 1070 mm (42 1/8″) |
| Exterior stairs and landings more than 10 m (32′ 9 11/16″) above the ground | 1500 mm (59 1/16″) |
The house rows also cover a house with a secondary suite. Every other guard starts from the 1070 mm rule.
A deck off the main floor is often under 1800 mm, so 900 mm applies. A deck off a second floor, or a balcony, is usually higher and needs 1070 mm. We set each guard to the height for where it goes and confirm it at the measure.
Stairs
On stairs, a guard’s height is measured from a line drawn through the front edges of the treads, the nosings, up to the top of the guard. Inside a house, stair guards are at least 900 mm. Outside, the 1800 mm rule applies to a stair the same way it does to a deck.
Most stairs also need a handrail, and a glass guard can be paired with a separate handrail.
Gaps and climbing
Openings in a required guard have to be small enough to stop a 100 mm (3 15/16″) ball, so a small child can’t slip through. On stairs, the triangle between the treads, the risers and the bottom of the guard has to stop a 150 mm (5 7/8″) ball. Our glass panels are set 1″ (25.4 mm) apart.
Ontario also asks that a required guard have nothing between 140 mm (5 1/2″) and 900 mm (35 7/16″) above the floor that makes it easy to climb. That rules out horizontal rails and cables that work like a ladder. A glass panel has nothing to step on.
The glass
Glass in a guard has to be safety glass: tempered or laminated, made to the CAN/CGSB-12.1 standard. Wired glass is also allowed. Each pane of safety glass carries a small permanent mark that shows it.
Tempered glass is heat-treated to be several times stronger than ordinary glass, and breaks into small, blunt pieces. Laminated glass bonds two panes to an interlayer that holds the glass in place if it breaks. We use 12 mm tempered glass for spigot and standoff railings, 10 mm or 12 mm tempered for post and clamp, and laminated tempered glass in base shoe.
A guard also has to carry the loads the Code sets out, so the glass, the spigots or channel, and the fixings into the deck or slab are chosen together.
Condo and apartment balconies
Larger buildings, such as condo and apartment towers, follow SB-13, the Building Code standard for glass in guards. It sets the glass by how close it sits to the edge of the floor or slab.
| Where the glass sits | Glass allowed |
|---|---|
| Beyond the slab edge, or within 50 mm (1 15/16″) of it | Heat-strengthened laminated |
| More than 50 mm in from the edge | Heat-strengthened laminated, or heat-soaked tempered |
| More than 150 mm (5 7/8″) in from the edge | Either of those, or tempered glass no more than 6 mm thick |
Laminated glass in these guards has to stay in its frame if it breaks. Replacement panels in a condo go through the property manager, and we match them to the building’s system.
Before you build
- Ask your city’s building department whether your deck, balcony or stair needs a permit.
- Around a pool, your city’s pool enclosure by-law also applies, with its own rules for height and gates.
- In a condo, changes to a balcony go through the property manager and the board.
- Book a free measure, and we confirm the height of each guard before the glass is made.
Sources
- Ontario Regulation 163/24, Building Code, Ontario e-Laws
- SB-13, Glass in Guards, 2024 Building Code Compendium
- Safety glazing marking, City of Kitchener building bulletin BB 2025-08
Have us come measure, free.
We measure at your home or site at no charge, then send a written quote.