Ontario deck railing code requirements
The rules that matter for a residential deck in Ontario: a guard is generally required once the deck surface is more than 600 mm (about 24") above grade; the guard must be at least 900 mm (36") high up to 1,800 mm (5'11") above grade and 1,070 mm (42") above that; and openings can't pass a 100 mm (4") sphere. Plain-language summary by an installer — not legal advice; your municipal building department has the final word.
When a deck needs a guard at all
The Ontario Building Code triggers a guard when there's a drop: for houses, a walking surface more than 600 mm above the adjacent ground generally needs one. Below that, a railing is optional — common anyway for looks, grip, and resale.
The 36 vs 42 inch rule
- Deck surface up to 1,800 mm (5'11") above grade: guard at least 900 mm (36") high.
- Deck surface above 1,800 mm: guard at least 1,070 mm (42") high. Walkout-basement decks are almost always in this class.
Height is measured from the walking surface — and from anything standable beside the guard, like a built-in bench (see FAQ).
Openings and climbability
Openings in a residential guard generally can't pass a 100 mm (4") sphere — that's the picket-spacing rule — and guards between roughly 140 mm and 900 mm above the deck can't have elements that make them easy to climb. Horizontal ladder-style designs are the classic fail; vertical pickets and glass panels pass by design.
Strength
Guards must resist specified loads — pushing out on the top rail, down on it, and against the infill. In practice this is about anchoring: posts bolted into solid rim joists or concrete, not screwed into deck boards. It's the difference between a railing and a suggestion.
Glass on decks
Glass used in a guard must be safety glass — tempered or laminated — and glass guard systems in Ontario generally require engineering behind them. The systems we install carry that engineering already; the heights and spacing above still apply. Full glass detail is in the general Ontario railing code guide.
Deck stairs
Exterior stairs with more than three risers generally need a handrail at 865–965 mm above the nosings, and the open side of a stair with a drop needs a guard. Most deck stair railings do both jobs at once. More on exterior stair railings.
Permits
New decks above 600 mm generally need a building permit, and the guard is reviewed as part of it. Like-for-like railing replacement on an existing deck usually doesn't. Municipality specifics — Toronto, Pickering, Ajax, Whitby, Markham and more — are in our railing permit guide.
What this means for your project
Every system we install — aluminum picket, framed glass, and frameless glass — is built around these numbers by default. Send photos of the deck and we'll tell you which height class you're in and what it costs: deck railings · deck railing cost.
This guide summarizes common residential requirements under the Ontario Building Code in plain language. It isn't a code document or legal advice — confirm specifics with your municipal building department before you build.
Deck code questions
My deck is exactly 24 inches off the ground. Do I need a railing?
At 600 mm (about 24 inches) or less above grade, the OBC generally doesn't require a guard on a residential deck. Right at the line, measure carefully — and consider that a deck used by kids or older family members may deserve one regardless.
Can I use 2x2 wood pickets to fix spacing on an old deck rail?
You can patch spacing, but if the guard is also under height or loose at the posts, patching doesn't make it compliant — and a pre-sale home inspection will flag it. That's usually the point where replacement makes more sense.
Does a bench against the deck edge change the guard rules?
Yes — anything that can be stood on next to the guard effectively raises the walking surface, so the guard height is measured from it. Built-in benches at deck edges are a classic inspection catch.
Who checks that my new deck railing meets code?
If the deck needed a permit, the municipal building inspector checks the guard as part of inspections. No permit doesn't mean no standard — it means nobody checks until something happens or the house sells. We build to code either way.
Want it built to code without the homework?
Text a photo of your stairs, porch, or deck and we'll send you a real number — usually the same day.
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