2024 Ontario Building Code Stair Requirements: Rise, Run, and Uniformity Standards
Sarah's Expert Insight
OBC Compliance Specialist
"The 10mm maximum tolerance across a full flight of stairs is where many DIY projects and inexperienced builders fail their inspections in London and Oakville. At empcontracting.ca Inc. your construction contractor in London, Ontario, we use precision leveling and CAD-based planning to ensure every riser is perfectly uniform, which is especially critical when dealing with custom finishes like Muskoka-style timber treads or modern oak stairs."
Navigating the 2024 Ontario Building Code (OBC) is essential for ensuring safety and compliance in residential and commercial builds. Section 9.8.4. outlines specific dimensions for rectangular treads, tapered treads, and the critical tolerances required for stair construction.
Understanding Table 9.8.4.1: Rise and Run Dimensions
The OBC distinguishes between different types of stairs, each with its own set of maximum and minimum requirements to ensure user safety. For private stairs—which include interior stairs in houses, secondary suites, and individual dwelling units—the code specifies:
- Maximum Rise: 200 mm
- Minimum Rise: 125 mm
- Maximum Run: 355 mm
- Minimum Run: 255 mm
Public vs. Service Stair Requirements
Public stairs, often found in shared residential buildings or commercial settings, have a stricter maximum rise of 180 mm and a minimum run of 280 mm. Service stairs and those leading to unoccupied attics or crawl spaces offer more flexibility with 'no limit' on maximum rise, provided they maintain the minimum 125 mm safety threshold.
Dimensions for Treads and Tapered Steps
According to Article 9.8.4.2, the depth of a rectangular tread must be at least equal to its run and cannot exceed the run plus 25 mm. This ensures a consistent footward strike. For tapered treads, the narrow end must be at least 150 mm wide, and the run must meet standard dimensions when measured 300 mm from the center line of the handrail.
Strict Uniformity and Riser Tolerances
Article 9.8.4.4 is one of the most scrutinized sections during site inspections. To prevent trip hazards, the OBC mandates:
- A maximum tolerance of 5 mm between adjacent treads or landings.
- A maximum tolerance of 10 mm between the tallest and shortest risers in an entire flight.
When you are planning a renovation or new build, working with empcontracting.ca Inc. your construction contractor in London, Ontario ensures that these technical specifications are met with precision to pass every municipal inspection.
Disclaimer: This content is generated from the Ontario Building Code for educational purposes. Always consult with a licensed professional engineer or your local building department before starting any construction project in London, Ontario.