What are the fire damper requirements for ductwork in a Toronto multi-unit building?

Fire dampers are required wherever ductwork penetrates a fire-rated assembly in a multi-unit building, including fire separations between dwelling units, corridor walls, floor assemblies, and any rated fire wall. This is one of the most critical life-safety provisions in the Ontario Building Code Part 6, and it applies to all multi-unit residential buildings in Toronto — from duplexes and townhouses to high-rise apartment and condo towers.

How fire dampers work: A fire damper is a mechanical device installed inside the duct at the point where it passes through a fire-rated wall or floor. The damper contains a fusible link — a heat-sensitive element that melts at a specific temperature (typically 74 degrees Celsius or 165 degrees Fahrenheit). When the link melts, a spring-loaded blade closes across the duct opening, blocking the passage of fire and hot gases. This prevents fire from travelling through the duct system from one fire-rated compartment to another, which is critical in multi-unit buildings where fire containment between units is the primary life-safety strategy.

The OBC specifies that fire dampers must carry a fire protection rating equal to the fire-resistance rating of the assembly they are installed in. For most residential fire separations between units, this means a one-hour fire-resistance rating, requiring a fire damper with a minimum one-hour fire protection rating. Floor assemblies in multi-storey buildings may require one and a half hour or two-hour rated dampers depending on the building classification. All fire dampers must be ULC-listed (Underwriters Laboratories of Canada) and installed according to the manufacturer's instructions and the listing conditions.

Smoke dampers are a related but separate requirement. In some buildings, particularly those with central HVAC systems serving multiple units, the OBC and the Ontario Fire Code may require combination fire and smoke dampers that close both in response to heat and upon receiving a signal from the building's fire alarm system. Smoke dampers prevent smoke migration through the duct system during a fire — smoke inhalation is the leading cause of fire deaths, and duct systems can rapidly distribute smoke throughout a building if not properly dampered.

Access and maintenance are often overlooked but code-required aspects of fire damper installations. Every fire damper must have an access door in the duct on one or both sides of the rated assembly, allowing inspection, testing, and resetting of the damper. The Ontario Fire Code requires fire dampers to be inspected and tested annually in most multi-unit buildings. During inspection, the damper is manually tripped to verify it closes fully, and the fusible link is visually inspected for corrosion or damage. Many GTA building owners and property managers neglect this requirement, which can result in fire code violations during a fire marshal inspection.

If you are renovating a unit in a Toronto multi-unit building and your contractor needs to modify or add ductwork that penetrates a fire separation, fire damper installation is non-negotiable and permit-required. The installation must be inspected by the City of Toronto Building Division to verify proper rating, placement, and access. Budget approximately $150 to $400 per fire damper installed, depending on size and type. This is a life-safety item — never allow a contractor to skip fire dampers to save money or simplify the installation.