Ontario Building Code Fireproofing Requirements
A comprehensive reference for contractors, engineers, and building owners on fire resistance requirements under the Ontario Building Code.
Overview of OBC Fire Protection Framework
The Ontario Building Code (OBC) establishes fire protection requirements primarily through Division B, Part 3 (Fire Protection, Occupant Safety and Accessibility). The key sections governing structural fireproofing are:
- Section 3.1.5: Fire Separations — requirements for fire-rated assemblies between different occupancies, suites, and compartments.
- Section 3.2.2: Building Size and Construction — establishes the relationship between building type (combustible vs. noncombustible construction), height, area, and required fire resistance ratings for structural elements.
- Section 3.2.6: Additional Requirements for High Buildings — enhanced fire protection for buildings over 36 metres in height.
- Section 9.10: Fire Protection of residential buildings (Part 9 buildings under 600 m² per floor).
Fire Resistance Ratings by Building Type
The OBC classifies buildings by construction type and assigns minimum fire resistance ratings to structural elements based on building height, area, and occupancy. The following table summarizes the key requirements from OBC Table 3.2.2.38 (Fire Resistance Ratings for Structural Members):
| Building Description | Floors | Roof | Columns | Loadbearing Walls |
|---|---|---|---|---|
| High-rise (over 6 storeys) | 2 hr | 1.5 hr | 2 – 4 hr | 2 hr |
| Mid-rise (4 to 6 storeys, noncombustible) | 1.5 – 2 hr | 1 hr | 2 hr | 1.5 – 2 hr |
| Low-rise (1 to 3 storeys, noncombustible) | 1 hr | 45 min – 1 hr | 1 hr | 1 hr |
| Single-storey industrial / warehouse | N/A | 45 min – 1 hr | 1 hr | 1 hr |
| Parking garage (noncombustible) | 1.5 – 2 hr | 1 hr | 2 hr | 2 hr |
Note: These are simplified summaries. Actual required ratings depend on specific occupancy classifications, building area relative to allowable maximums, sprinkler trade-offs, and other code provisions. A professional code review is always recommended.
CAN/ULC Testing Standards
All fireproofing materials and assemblies used in Ontario must be tested and listed to applicable CAN/ULC standards. The key standards for structural fire protection are:
CAN/ULC-S101: Standard Methods of Fire Endurance Tests of Building Construction and Materials
The primary fire test standard for determining fire resistance ratings. Assemblies are exposed to a standardized fire in a furnace following the CAN/ULC-S101 time-temperature curve, which reaches 538°C at 5 minutes, 704°C at 10 minutes, 843°C at 30 minutes, and 927°C at 60 minutes. Structural steel members must maintain their load-bearing capacity throughout the rated exposure period.
CAN/ULC-S705.1: Standard for Thermal Insulation — Spray Applied Rigid Polyurethane Foam, Medium Density — Material Specification
Governs the material properties of medium-density spray polyurethane foam (spray foam insulation). Specifies requirements for thermal resistance, density, compressive strength, water absorption, and fire performance. Relevant for spray foam used as insulation in assemblies that also require fire resistance.
CAN/ULC-S705.2: Standard for Thermal Insulation — Spray Applied Rigid Polyurethane Foam, Medium Density — Application
Specifies installation requirements for spray foam insulation including substrate preparation, environmental conditions during application, maximum lift thickness, and quality control procedures. Compliance with S705.2 is required by the OBC for all spray foam insulation installations.
CAN/ULC-S712.1: Standard for Thermal Insulation — Light Density, Open Cell Spray Applied Semi-Rigid Polyurethane Foam — Material Specification
The material specification for open-cell (light density) spray polyurethane foam. Defines requirements for thermal resistance, density, air permeance, water vapour permeance, and fire test performance specific to open-cell formulations.
CAN/ULC-S712.2: Standard for Thermal Insulation — Light Density, Open Cell Spray Applied Semi-Rigid Polyurethane Foam — Application
Installation standard for open-cell spray foam. Covers substrate requirements, temperature and humidity conditions, maximum pass thickness, curing time, and quality assurance procedures specific to open-cell foam applications.
Spray-Applied Fire Resistive Materials (SFRM)
SFRM is the most widely used structural steel fireproofing method in Ontario. These cementitious or gypsum-based materials are spray-applied directly to structural steel members to achieve the required fire resistance ratings. Key points:
- Thickness determination: The required SFRM thickness is specified by the fire-rated assembly design listed with UL (Underwriters Laboratories), Intertek (WHI), or other recognized testing agencies. Thickness varies based on the steel section size, weight, and required fire rating.
- Application standards: SFRM application must conform to the manufacturer's specifications and the listing requirements. Minimum bond strength, density, and thickness must be verified through testing.
- Inspection requirements: Ontario municipalities require SFRM thickness verification as part of the building permit inspection process. Measurements are typically taken using electronic thickness gauges at a density meeting statistical sampling requirements.
- CaliberQA documentation: Many municipalities and engineers require CaliberQA (or equivalent) third-party inspection and documentation to verify SFRM thickness and quality compliance.
Residential Fireproofing Requirements (OBC Part 9)
Residential buildings covered under Part 9 of the OBC have specific fire separation requirements:
- Attached Garage Separation (OBC 9.10.9.6): A fire separation with at least a 45-minute fire resistance rating is required between an attached garage and the dwelling. This includes the garage ceiling, walls, and any doors connecting to the house.
- Party Walls — Semi-Detached and Townhouses (OBC 9.10.9.8): Fire separations between dwelling units in semi-detached houses, duplexes, and townhouses must achieve a minimum 1-hour fire resistance rating from the foundation to the underside of the roof sheathing.
- Secondary Suites: Basement apartments and secondary suites require fire separations with at least a 1-hour rating between the suite and the rest of the dwelling, including the ceiling assembly.
- Thermal Barrier Requirement: When spray foam insulation is used, the OBC requires a 15-minute thermal barrier (typically 12.7 mm gypsum board) to protect the foam from fire exposure in occupied spaces.
Working with Unique Fireproofing on OBC Compliance
Our team has extensive experience navigating OBC fireproofing requirements for projects of all types and sizes across the Greater Toronto Area. We provide:
- Code analysis and fire resistance rating determination for your specific building
- SFRM product selection from our CAFCO and Isolatek product lines
- Certified installation by CUFCA-licensed technicians
- CaliberQA inspection documentation and thickness reports
- Coordination with municipal building inspectors for permit sign-off
- Written warranties and certificates of conformance