What is the maximum stair rise and minimum run in Ontario?
For private stairs in houses, the maximum rise is 200 mm (7-7/8 in) and the minimum run is 255 mm (10 in), with rise at least 125 mm and run at most 355 mm. Steps must be uniform within the flight.
Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.
Ontario adopted the larger 255 mm minimum run (up from the old 210 mm) effective January 1, 2022, so older plans and habits produce non-compliant stairs; a typical basement stair now needs more horizontal space, which catches renovators off guard. Uniformity matters as much as the limits: inspectors measure every riser, and a mismatched bottom step from a late flooring change is the classic failure. Plan finished floor thicknesses before cutting stringers, and remember minimum headroom of 1,950 mm over private stairs.
Each step in your house can rise at most 200 mm and must give your foot at least 255 mm of depth. Every step in a flight must match, because one odd step is exactly where people trip.
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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.