OBC Firestop and Service Penetration Requirements: A Guide by empcontracting.ca Inc.
Sarah's Expert Insight
OBC Compliance Specialist
"In my work across London, Oakville, and Muskoka, I often see projects delayed because the 600mm offset for outlet boxes or the specific FT ratings for firestops were overlooked during the rough-in phase. At empcontracting.ca Inc., we prioritize these technical details early in the construction process to ensure seamless inspections and, more importantly, the long-term safety of the building's occupants."
Understanding the complexities of the 2024 Ontario Building Code (OBC) is essential for any major renovation or new build. As empcontracting.ca Inc. your construction contractor in London, Ontario, we ensure every penetration through fire-rated assemblies meets the stringent safety standards required by law.
Horizontal Fire Separations and Firestop Ratings
According to Section 3.1.9.1., service equipment penetrating a horizontal fire separation must be sealed with a firestop that meets the CAN/ULC-S115 standard. The 'F rating' of the firestop must match or exceed the fire-resistance rating of the separation itself. These penetrations are typically permitted when contained within concealed floor/ceiling spaces or horizontal service spaces.
Service Equipment Penetrations (3.1.9.2.)
General service equipment, including ducts, pipes, electrical wires, and optical fibre cables, are permitted to penetrate fire-rated membranes provided they are protected by an approved firestop. Additionally, combustible raceways embedded in concrete must have at least 50 mm of concrete cover from the bottom of the slab to maintain structural and fire integrity.
Specific Regulations for Outlet Boxes (3.1.9.3.)
Outlet boxes represent a common penetration point in residential and commercial builds. The OBC mandates:
- FT Ratings: Penetrations must be sealed by firestops with an FT rating equal to the assembly's fire-resistance rating.
- Size Restrictions: Noncombustible boxes must not exceed 0.016 m² individually or an aggregate of 0.065 m² within any 9.3 m² of surface area.
- Separation Distances: Boxes on opposite sides of a vertical fire separation must be separated by at least 600 mm unless specifically fire-blocked or protected by a firestop.
Combustible Piping Penetrations (3.1.9.4.)
Combustible sprinkler and water distribution piping are permitted to penetrate fire separations under specific conditions. For sprinkler systems, the compartments on both sides of the separation must be sprinklered. Water distribution piping requires specific firestop protection in accordance with the assembly's rating.
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.