How high should a stair handrail be inside an Ontario home?

The 2024 Ontario Building Code sets the required height for a handrail on a private stair inside a dwelling unit at 865 mm to 1 070 mm, measured from a line drawn tangent to the tread nosings.

A few other Code points bear on how a handrail is installed. Within a single dwelling unit, a stair narrower than 1 100 mm needs a handrail on one side only. A handrail is not required at all on an interior stair with no more than 2 risers. The handrail must be continuously graspable from the bottom riser to the top riser, though in a single dwelling unit it may begin at a newel post or volute on the bottom tread. Clearance behind the handrail must be at least 50 mm, or 60 mm where it runs against a rough surface.

For attachment, 9.8.7.7.(2) describes a handrail in a single dwelling unit fastened at points no more than 1.2 m apart, with the first point within 300 mm of each end, using no fewer than two No. 8 wood screws per point penetrating at least 32 mm into solid wood.

One distinction worth keeping clear: handrail height (865 mm to 1 070 mm) and guard height are separate requirements. A guard is required where the drop beside a stair or landing exceeds 600 mm, and inside a dwelling unit a guard must be at least 900 mm (about 35 1/2 in.) high. The two numbers are not interchangeable.

If you are replacing or adding a handrail on an existing stair, confirm with the City of Ottawa whether the work requires a permit before a carpenter starts.