NBC 2025 Stair Tread and Riser Dimensions: A Guide for London, Ontario Construction
Sarah's Expert Insight
Senior Consultant at empcontracting.ca Inc.
"The transition to NBC 2025 standards emphasizes even tighter tolerances for stair uniformity, which is a frequent point of failure during framing inspections in the London area. At empcontracting.ca Inc. your construction contractor in London, Ontario, we focus on these granular details early in the planning phase to ensure our clients avoid costly retrofits and provide the safest possible environment for their families."
Navigating the National Building Code of Canada (NBC) 2025 is essential for ensuring structural safety and accessibility. One of the most critical components of any build is the stairwell, where precise measurements prevent accidents and ensure compliance with municipal standards. At empcontracting.ca Inc. your construction contractor in London, Ontario, we specialize in implementing these technical requirements with surgical precision.
Understanding NBC 2025 Stair Riser and Tread Standards
The NBC 2025 continues to emphasize the importance of uniformity in stair construction to reduce the risk of fall-related injuries. For private dwellings falling under Part 9 of the code, the dimensions for steps are strictly regulated.
Stair Riser Requirements
The riser is the vertical height between each step. According to the NBC 2025 standards:
- Maximum Riser Height: 200 mm (7 7/8 inches)
- Minimum Riser Height: 125 mm (4 7/8 inches)
Consistency is key; the code allows for a maximum variation of only 5 mm between the highest and lowest riser in a single flight of stairs.
Stair Tread (Run) Requirements
The tread, or 'run,' is the horizontal distance from the face of one riser to the next. For residential applications, the requirements are:
- Minimum Tread Depth (Run): 255 mm (10 inches)
- Maximum Tread Depth: Not specified, though ergonomics dictate a standard range for comfort.
Uniformity and Tolerances
The NBC 2025 mandates that all steps in a flight must be uniform. Large variations in tread depth or riser height create 'trip points' that the human brain cannot anticipate while descending. Expert builders at empcontracting.ca Inc. your construction contractor in London, Ontario, ensure that every staircase meets the strict 5 mm to 6 mm tolerance levels required by local building inspectors.
Public and Commercial Staircase Dimensions
For public buildings and assembly occupancies, the requirements shift slightly to accommodate higher traffic volumes and enhanced accessibility. Generally, public stairs require a shallower riser (maximum 180 mm) and a deeper tread (minimum 280 mm) to facilitate safer passage for diverse populations.
Handrails and Guarding
Beyond the dimensions of the steps themselves, the NBC 2025 requires that handrails be installed at a height between 865 mm and 1070 mm. If you are planning a renovation or new build, consulting with a professional ensures these complex measurements are handled correctly from the design phase through to the final inspection.