2024 Ontario Building Code: Expert Guide to Roof Coverings, Fabrics, and Occupant Load
Sarah's Expert Insight
OBC Compliance Specialist
"Navigating these fire-safety and capacity regulations is vital for commercial developments in London and high-end timber builds in Muskoka or Oakville. At empcontracting.ca Inc., we emphasize that failing to post correct occupant load signage or using non-compliant roofing on mass timber projects can lead to significant liability and permit holdups during the final inspection phase."
Navigating the complexities of the 2024 Ontario Building Code (OBC) is essential for any successful commercial or residential build. As empcontracting.ca Inc. your construction contractor in London, Ontario, we prioritize compliance with the latest fire safety and structural standards to protect your investment.
3.1.15.2. Roof Covering Classifications and Fire Standards
Under the 2024 OBC, most roof coverings are required to meet Class A, B, or C fire classifications. These classifications are determined by their resistance to external fire exposure. However, specific exemptions apply for:
- Tents and air-supported structures.
- Small Group A, Division 2 buildings (under 2 storeys and 1,000 m²) with noncombustible underlay.
- Steel building systems using metal sheets, shingles, masonry, or concrete.
Requirements for High-Rise and Mass Timber
For high-density developments exceeding 25 meters in height—including encapsulated mass timber constructions—a Class A classification is mandatory. This ensures that the highest point of the roof remains resilient against fire spread in vertical urban environments.
3.1.16.1. Flame Resistance for Fabric Awnings and Canopies
Any fabric components used in awnings, canopies, or marquees attached to a building must conform to CAN/ULC-S109, the "Standard Method of Flame Tests of Flame-Resistant Fabrics and Films." This is a non-negotiable safety requirement for commercial storefronts and public assembly spaces.
3.1.17.1. Determining Occupant Load for Safety
Accurate occupant load determination is critical for egress and life safety. The OBC calculates capacity based on:
- The number of fixed seats in assembly areas.
- Two persons per sleeping room in residential dwelling units.
- Specific floor area factors found in Table 3.1.17.1.
Signage and Compliance
If a floor area is designed for a custom occupant load, a permanent sign must be posted in a conspicuous location. Furthermore, mezzanines and balconies are legally regarded as part of the floor area when calculating total capacity.
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.