Free tool Decks Building Code

Deck Code Checker: Railing Height, Baluster Gaps and Stairs

Enter your deck height, railing, balusters and stairs. The checker tests them against the Ontario Building Code numbers inspectors use for private decks and stairs.

Short version: Over 600 mm (about 24 in) above the ground a deck needs a guard: at least 900 mm (36 in) high, or 1,070 mm (42 in) once the deck is more than 1,800 mm up. Gaps must stop a 100 mm (4 in) sphere. Stair rise 125-200 mm, run at least 255 mm, and a handrail 865-1,070 mm high when there are more than 3 risers.

Check your deck

UnitsDeck height above the groundGuard (railing) height, measured from the deckWidest gap between balustersNumber of stair risersRise of each stepRun of each stepStair handrail height (0 if none)

The numbers this checker uses

Guard required: where the walking surface is more than 600 mm above the ground.
Guard height: at least 900 mm, or at least 1,070 mm where the deck is more than 1,800 mm above the ground.
Openings: must not let a 100 mm sphere pass.
Private stairs: rise 125 to 200 mm, run at least 255 mm, steps uniform within 6 mm.
Handrail: required with more than 3 risers, 865 to 1,070 mm high.

Details and the full code references: Deck railing height in Ontario and Deck stairs and handrails in Ontario.

What the checker does not cover

Guard strength and loads, footings, joist spans, ledger attachment and setbacks are separate checks. See deck framing, joists and beams, deck footings and deck permits in Ontario.

Questions people ask

How high does a deck railing need to be in Ontario?

At least 900 mm (about 36 in) where the deck is not more than 1,800 mm above the ground, and at least 1,070 mm (about 42 in) above that.

When does a deck need a railing in Ontario?

When the walking surface is more than 600 mm (about 24 in) above the ground next to it.

What is the maximum gap between deck balusters?

Openings must not let a 100 mm (4 in) sphere pass through.

What are the stair rules for a deck?

For private stairs, each rise must be 125 to 200 mm and each run at least 255 mm, and a handrail 865 to 1,070 mm high is needed when there are more than 3 risers.

Related guides on BuildersOntario

Deck railing height Ontario36 in, 42 in and the rules that decide which Deck stairs and handrailsRise, run, landings and handrails Deck building calculatorMaterials and cost for your deck Deck permit OntarioWhen you need one and what to submit

Building in Simcoe County or on Georgian Bay?

We are ICFhome.ca, a family builder in Tiny Township with 45 years of custom homes behind us. Pick the path that matches where you are.

Send plans for review Ballpark estimate Book a call Visit the showhome

Updated November 2026. A planning tool based on Ontario Building Code guard and private-stair rules; your building department makes the final decision.