Question 1

What's the tallest riser allowed on stairs inside an Ontario house?

Accepted Answer

For private stairs within a dwelling unit, the tallest riser the 2024 Ontario Building Code allows is 200 mm, measured nosing to nosing. The minimum is 125 mm, so every riser in the flight has to land between those two numbers. The Code also requires that no two adjacent risers differ by more than 5 mm, and no two risers anywhere in the same flight differ by more than 10 mm. That uniformity rule matters as much as the maximum, because an inconsistent riser is what catches a foot.

Question 2

Which code limits apply to a curved staircase in an Ottawa home?

Accepted Answer

A curved staircase inside a dwelling unit follows the same 2024 Ontario Building Code private-stair rules as any other interior stair, with one exception: if the curve is achieved through winders, specific winder rules apply, and if the design is a true spiral, a separate set of numbers takes over entirely.

Question 3

What load must stairs in an Ottawa house be built for?

Accepted Answer

For stairs serving a single dwelling unit, clause 9.8.9.1.(1)(a) of the 2024 Ontario Building Code (O. Reg. 163/24) sets the design load at 1.9 kPa. For a private stair within a dwelling unit, the Part 9 prescriptive rules give the carpenter the member sizes that satisfy the Code without a full structural calculation, provided the stair stays within the limits of those tables.

Question 4

Spiral staircase up to a loft in my Ottawa home, allowed?

Accepted Answer

Spiral stairs are allowed inside a house under the 2024 Ontario Building Code (O. Reg. 163/24), but clause 9.8.4.7. gives them their own numbers in place of the usual private-stair table. For a spiral stair, 9.8.4.7.(1) sets a clear width of at least 660 mm, risers of not more than 240 mm, treads at least 190 mm deep measured 300 mm from the centre line, headroom of at least 1 980 mm, and handrails on both sides, with the outer one at least 1 070 mm high.

Question 5

Moving my staircase to a different spot in my Nepean house?

Accepted Answer

Relocating a staircase is one of the more involved interior carpentry jobs: you are removing an existing stair structure, framing a new opening in the floor, and building a new flight in a different location. The City of Ottawa lists adding or removing walls and structural alterations as permit work, and cutting a new stair opening changes the floor framing, so confirm with Building Code Services at ottawa.ca before any work begins.

Interior Stairs

What's the tallest riser allowed on stairs inside an Ontario house?

Which code limits apply to a curved staircase in an Ottawa home?

What load must stairs in an Ottawa house be built for?

Spiral staircase up to a loft in my Ottawa home, allowed?

Moving my staircase to a different spot in my Nepean house?