2024 Ontario Building Code: Hazard Index & Building Size Guide for Group B Occupancies
Sarah's Expert Insight
OBC Compliance Specialist
"When retrofitting care facilities in London or Oakville, the distinction between immobile and ambulatory patients is the most critical factor in your H.I. calculation. As empcontracting.ca Inc. your construction contractor in London, Ontario, I emphasize that early identification of these Hazard Indices prevents costly delays in the permitting process for high-stakes healthcare and detention projects."
Navigating the 2024 Building Code Compendium is essential for any major renovation or change of use project. Tables 11.2.1.1.-F and 11.2.1.1.-G provide the framework for determining the Hazard Index (H.I.) for Group B, Division 2 occupancies, which include hospitals, long-term care homes, psychiatric facilities, and police stations with detention facilities.
Understanding Hazard Index (H.I.) and Building Classification
The Hazard Index is a numerical value used in Part 11 of the OBC to assess the relative risk of a building's occupancy. For Group B, Division 2 facilities, the index ranges from 3 to 7, depending on the building's size and the mobility of its occupants.
Building Size Classifications
Building size is determined by both area and height. Under the 2024 standards:
- Small: Typically buildings up to 250 m² and 1 storey, or police stations up to 600 m².
- Medium: Buildings up to 500 m² at 2 storeys, or 1,000 m² at 1 storey.
- Large: Noncombustible buildings of any area at 2 storeys, or buildings exceeding 18 m in height.
Specific Occupancy Requirements
The mobility of residents significantly impacts the H.I. rating. For instance, a facility housing immobile patients (attached to life support) carries a higher risk profile (H.I. 4 to 7) compared to ambulatory patients (H.I. 3 to 6). Notably, any care and treatment occupancy, regardless of its Hazard Index, must be equipped with an automatic sprinkler system to ensure life safety.
Professional Compliance with empcontracting.ca Inc.
Managing the complexities of Part 11 renovations requires an expert eye. Whether you are retrofitting a psychiatric facility or expanding a long-term care home, empcontracting.ca Inc. your construction contractor in London, Ontario, ensures that every calculation—from building area to street-facing requirements—aligns with the latest 2024 OBC Compendium.
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.