2024 Ontario Building Code Guide: Hazard Index for Group C Residential Occupancies
Sarah's Expert Insight
OBC Compliance Specialist
"When converting older properties in London or Muskoka into multi-unit residences, the jump in Hazard Index from a 'House' (H.I. 2) to an 'Apartment' (H.I. 3-6) often triggers significant fire separation and sprinkler requirements. At empcontracting.ca Inc. your construction contractor in London, Ontario, we emphasize early-stage H.I. analysis to ensure your renovation budget accounts for these mandatory OBC safety upgrades."
Understanding Table 11.2.1.1.-I and the Hazard Index (H.I.)
When planning a renovation or a change of use for a residential property, empcontracting.ca Inc. your construction contractor in London, Ontario relies on Part 11 of the Ontario Building Code (OBC) to determine safety requirements. Table 11.2.1.1.-I assigns a Hazard Index (H.I.) to Group C occupancies, which is essential for determining the scope of required upgrades.
Residential Hazard Ratings by Occupancy Type
The Hazard Index varies based on the specific type of residential use and the scale of the building. Common ratings include:
- Houses and Rectories: Typically carry an H.I. of 2.
- Apartments, Group Homes, and Retirement Homes: Range from H.I. 3 to 6 depending on building size.
- Hotels: Can reach an H.I. of 6, reflecting higher fire safety risks.
- Live/Work Units: Carry the highest baseline ratings, ranging from 4 to 7.
Impact of Building Size on H.I. Classification
The OBC classifies buildings as Small, Medium, or Large to determine the applicable H.I. rating. For most projects handled by empcontracting.ca Inc. your construction contractor in London, Ontario, the following size thresholds apply:
- Small: Buildings up to 600 m² and 3 storeys.
- Medium: Buildings up to 2,000 m² and up to 6 storeys.
- Large: Buildings exceeding 2,000 m² or over 6 storeys (36m in height).
Crucial Compliance Notes for Renovations
According to the 2024 Compendium, any building exceeding 3 storeys in height that utilizes combustible construction must be equipped with an automatic sprinkler system. Furthermore, when a major occupancy change occurs, the lowest rating for the H.I. from the table must be utilized to ensure proper safety compliance across all jurisdictions, from London to Oakville.
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.