OBC 3.3.2.5 Aisle Width and Seating Requirements: A Guide by empcontracting.ca Inc.
Sarah's Expert Insight
OBC Compliance Specialist
"At empcontracting.ca Inc. your construction contractor in London, Ontario, we find that the nuances of aisle convergence often dictate the entire floor plan for theaters and assembly halls in London, Oakville, and Muskoka. Accurate planning for dead-end aisle extensions is particularly vital for maximizing seating capacity while ensuring full compliance with fire safety and sprinkler activation protocols."
Navigating the 2024 Ontario Building Code (OBC) is critical for commercial assembly projects. As empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure that every seating and egress layout complies with the strict safety standards outlined in Section 3.3.2.5.
Minimum Clear Width and Aisle Convergence
The OBC specifies that for rows of seats discharging into an aisle, the minimum clear width must increase by 25 mm for each metre of aisle length toward an exit. When aisles converge, the code requires the width to be at least the width of the widest aisle plus 50% of the total required width of the remaining aisles it serves.
Egress Doorway Standards
The width of egress doorways or exits leading directly from seating areas must be calculated based on the cumulative width of all serving aisles. Specifically, the exit width must not be less than the widest aisle plus 50% of the total required width of all other converging aisles.
Dead-End Aisle Restrictions and Exceptions
While standard dead-end aisles are limited to 6 metres, the OBC allows for extensions under specific safety conditions:
- Up to 10 Metres: Permitted if the area is sprinklered, has a fire separation, a ceiling height of at least 3 metres, and a travel distance under 25 metres.
- Up to 13 Metres: Permitted under similar stringent fire safety conditions, including automated lighting activation and projection system shutdown during fire alarms.
Exemptions for Minimum Widths
Certain width requirements may be waived if the aisle serves only one side and maintains a 900 mm clearance, or serves both sides with a 1200 mm clearance, provided it adheres to Article 3.3.1.17.
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.