Stairs are where most deck inspections fail and where most deck injuries happen. A step that is a centimetre taller than the others trips people every time. The rules are not complicated once you see them together, and knowing them helps you check a quote, a drawing or an old deck you are thinking of fixing.
Ontario deck stair rules at a glance
| Item | Requirement for stairs serving a house |
|---|---|
| Rise (height of each step) | 125 mm minimum, 200 mm maximum |
| Run (depth of each step, nosing to nosing) | 255 mm minimum, 355 mm maximum |
| Uniformity | Risers and treads kept uniform through the flight, with only a few millimetres of tolerance |
| Width | 860 mm (about 34 inches) minimum clear width |
| Handrail, when | Exterior stairs with more than three risers |
| Handrail height | 865 to 1,070 mm above the line of the nosings, graspable |
| Handrails on both sides | When the stair is wider than 1,100 mm |
| Guards, when | Any open side where the drop to the ground is more than 600 mm |
| Guard height on the deck | 900 mm where the deck is no more than 1,800 mm above grade, 1,070 mm above that |
| Openings | No opening that lets a 100 mm sphere through |
| Climbing | No rails or parts that make the guard easy to climb between 140 mm and 900 mm |
| Landings | At the top and bottom, at least as wide and as long as the stair is wide (up to 1,100 mm) |
These come from Section 9.8 of the Ontario Building Code. Your city applies the code through the building permit, and an inspector may add local requirements, so the approved drawings are the final word for your deck.
The 2022 change to the minimum run
The minimum run for stairs inside and serving a house went up from 210 mm to 255 mm for permit applications complete after December 31, 2021. Plenty of older decks in Hamilton and Halton have steps shallower than 255 mm. They are not illegal if they were built to the code of their day, but if you are rebuilding the stairs, the new ones need to meet the current number, which often means the stair takes up more ground.
How to lay out deck stairs: a worked example
Say the deck surface is 1,220 mm (48 inches) above a finished landing pad.
- Find the number of risers. Divide the total height by the maximum rise: 1,220 / 200 = 6.1. Round up to 7 risers.
- Find the actual rise. 1,220 / 7 = 174 mm per step, comfortably inside 125 to 200 mm.
- Find the number of treads. There is always one less tread than risers when the deck is the top step: 6 treads.
- Pick a run. 255 mm is the minimum. Around 280 mm (11 inches) feels better outdoors. 6 x 280 = 1,680 mm.
- Check the footprint. The stair needs about 1.7 m (5.5 ft) of ground in front of the deck, plus a landing at the bottom at least as long as the stair is wide.
- Check the comfort rule. A common check is two risers plus one run between about 600 and 650 mm. Here, 2 x 174 + 280 = 628 mm.
Measure the height from the deck surface to the finished landing, not to the dirt. If the landing is pavers still to be installed, the stair height changes.
Handrails and guards: the most failed items
- Handrail is not guard. A guard stops you falling off the side. A handrail is what you hold. A stair can need both, and a 2x6 cap on top of a guard is often too wide to grasp.
- Three-riser rule. Three risers or fewer, no handrail needed on exterior stairs of a house. Four or more, one handrail. Wider than 1,100 mm, a handrail on both sides.
- Graspable. Round rails around 30 to 43 mm across, or a shaped profile your hand can wrap around, with clearance behind it.
- Guards on stairs. If the stair side drops more than 600 mm, the stair needs a guard too, measured from the line of the nosings.
- Balusters. 100 mm maximum opening, including the triangle under the bottom rail on a stair.
For railing styles and prices, our Ontario deck cost guide covers pressure-treated, aluminum, cable and glass.
What deck stairs cost in 2026
| Stair | Typical scope | Installed price |
|---|---|---|
| Basic 3-step, pressure-treated | About 36 inches wide, no handrail needed | $600 - $1,200 |
| Standard stair run | Depends on height and material | $600 - $2,200 |
| Wide composite stair with landing | About 4 ft wide, composite treads, railings on both sides | $3,500 - $6,000 |
| Stair railings | Per linear foot, pressure-treated to glass | $50 - $350 |
| Stair riser lights | Part of a deck lighting package | Within $1,200 - $4,500 for a typical deck |
| Paver landing pad | Compacted base and pavers at the bottom | $22 - $40 per sqft |
Stairs are priced per run rather than per step, because the stringers, the landing and the railings drive most of the cost. Composite treads usually need stringers closer together than wood, often 12 inches (30 cm) apart, so a composite stair has more framing. Check your decking maker's stair span table.
Deck stair design ideas
Wide, shallow steps
A stair across a whole side of a low deck, with deep treads, doubles as seating and makes the deck flow into the yard. With three risers or fewer, no handrail is needed.
Box steps or stacked platforms
Two or three stepped platforms instead of a traditional stair. They suit low decks and look more like part of the design.
A landing with a turn
On a tall deck, a mid-height landing lets the stair turn 90 degrees, saves yard space and breaks up a long climb.
Stone or paver bottom landing
A proper landing at the bottom stops the stair sinking into mud and keeps the bottom step at a consistent height. It ties the deck into a patio below.
Riser and post lights
Low-voltage lights in the risers or on the posts make the stair safer at night and are easier to wire while the stair is being built.
Closed risers
Closed risers look cleaner, stop things falling through and keep the space under the stair hidden. If you want open risers, confirm the opening rule with your inspector first.
Where stair quotes cut corners
- Two stringers on a wide stair. Treads bounce and crack. Wood usually needs a stringer about every 16 inches, composite often every 12.
- Stringers on soil. The bottom of the stair needs a pad or footing.
- No handrail on four risers. A common inspection failure.
- Uneven top or bottom step. Check both with a tape once it is built.
- Guard cap used as a handrail. A flat 2x6 is not graspable.
- Run under 255 mm on a rebuild. Fine on a 1990 deck, not on new stairs.
Permits
New stairs on a deck that needs a permit are part of the permit drawings. Rebuilding or changing existing stairs and guards can also need a permit, especially on a raised deck. Our permit guide for Hamilton, Burlington and Oakville covers deck permit thresholds, fees and timelines.
Frequently asked questions
What is the maximum rise for deck stairs in Ontario?
200 mm, about 7.9 inches, for stairs serving a house. The minimum is 125 mm. Every riser in the flight should be the same height, within a few millimetres.
What is the minimum tread depth for deck stairs in Ontario?
The minimum run is 255 mm (10 inches) for permit applications complete after December 31, 2021. It was 210 mm before that. Around 280 mm feels more comfortable outdoors.
Do deck stairs need a handrail in Ontario?
Exterior stairs serving a house need a handrail when they have more than three risers. Stairs wider than 1,100 mm need a handrail on both sides.
How high should a deck stair handrail be?
Between 865 and 1,070 mm, measured vertically from a line through the front edges of the treads.
When does a deck need a railing in Ontario?
Where the walking surface is more than 600 mm above the ground. The guard must be at least 900 mm high if the deck is no more than 1,800 mm above grade, and 1,070 mm if it is higher.
How many steps do I need for my deck?
Divide the deck height by 200 mm and round up to get the number of risers. For a 1,220 mm deck, that is 7 risers of about 174 mm and 6 treads.
How much do deck stairs cost?
About $600 to $1,200 for a basic 3-step pressure-treated set, $600 to $2,200 for a typical stair run, and $3,500 to $6,000 for a wide composite stair with a landing and railings on both sides in 2026.
How far apart should deck stair stringers be?
About 16 inches apart for most wood treads, and often 12 inches for composite. Check the stair span table from your decking manufacturer.
- Our deck building service
- Deck cost in Ontario
- Deck repair cost in Ontario
- Pressure-treated vs cedar vs composite decking
- Deck cost calculator
Finishing the deck? See deck privacy wall ideas and costs that pass Hamilton and Oakville rules.