Fire dampers and smoke control under Canadian codes

Ductwork is a potential highway for fire and smoke. Every time a duct passes through a fire-rated wall or floor, it creates an opening in a barrier that the building code relies on to contain a fire. Fire dampers, smoke dampers and fire stop flaps close those openings when needed. They are simple devices, but they are installed out of sight, often in hard-to-reach locations, and they only work if they are correctly installed and periodically tested.

This guide explains the devices, where Canadian codes require them, and how owners can keep them working.

The three devices

Combination fire and smoke dampers meet both fire damper and smoke damper requirements in one assembly. They typically use a heat-responsive device plus an actuator controlled by the fire alarm system.

Dynamic fire dampers are rated to close against airflow, so they are used where fans may still be running when the damper closes. Static fire dampers are only for systems that shut down on fire alarm. Using a static damper in a system that keeps running can result in a damper that does not close fully.

Where the code requires them

Requirements come mainly from Part 3 of the National Building Code (NBC) and the provincial codes based on it. The exact provisions should be read from the edition in force, but in general:

Fire dampers

Fire dampers are required where a duct penetrates a fire separation that is required to have a fire-resistance rating. The code lists exceptions, which commonly include:

• Certain small noncombustible branch ducts serving one fire compartment, under specified conditions.
• Ducts in some sprinklered buildings or exhaust ducts that meet specific criteria.
• Penetrations of fire separations where the duct is part of a smoke control or other system that must continue operating, where fire dampers would defeat its purpose. Kitchen grease exhaust ducts are a notable example: NFPA 96 and the code require them to be enclosed rather than dampered.

Because the exceptions are specific and conditional, the designer should identify each fire separation crossing on the drawings and document whether a damper is required or excepted.

Smoke dampers

Smoke dampers are required less often under Canadian codes than fire dampers. They appear where the code requires measures to limit smoke movement, for example in some systems serving high buildings, interconnected floor spaces such as atria, and certain care and treatment occupancies. They are also used as part of engineered smoke control systems. See stairwell pressurization and smoke control systems.

Fire stop flaps

Fire stop flaps protect openings for diffusers and grilles in the ceiling membrane of rated floor-ceiling or roof-ceiling assemblies, where the ceiling is part of the tested fire-resistance design.

Installation matters

A fire damper only provides its rating if it is installed according to its listing and the manufacturer's instructions, which have been tested as an assembly with the wall or floor. Common installation requirements include:

1. A steel sleeve of the specified gauge, extending a set distance on both sides of the separation.
2. Retaining angles fastened to the sleeve on both sides of the wall, not to the wall itself.
3. Expansion clearance between the sleeve and the opening, so the damper can expand in a fire without crushing.
4. Breakaway duct connections, so collapsing ductwork does not pull the damper out of the wall.
5. Access doors in the ductwork, sized and located so the damper and fusible link can be inspected and reset.

Common deficiencies found during inspection include missing access doors, dampers installed in the wrong orientation, fusible links painted over or missing, sleeves sealed rigidly into walls, ductwork or wiring passing through the damper frame, and dampers jammed by debris or insulation. See common deficiencies found during commissioning.

Interaction with fan shutdown and fire alarm

The NBC requires certain air handling systems to shut down on fire alarm, and smoke control systems may instead need specific fans to run. Smoke dampers and combination dampers are controlled by the fire alarm system or a smoke control panel. These interactions must be:

• Clearly documented in a fire alarm and smoke control sequence or matrix.
• Coordinated between mechanical, electrical and fire protection designs.
• Verified in integrated testing under CAN/ULC-S1001. See integrated systems testing and CAN/ULC-S1001.

Inspection and testing in existing buildings

The National Fire Code of Canada (NFC) and provincial fire codes require building owners to maintain fire protection features, including closures such as fire dampers and fire stop flaps, in operating condition. They require periodic inspection, and the authority having jurisdiction may set specific frequencies.

Many owners and authorities also look to NFPA 80 (fire doors and other opening protectives) and NFPA 105 (smoke door assemblies and other opening protectives) for testing frequency. These call for operational testing after installation, then at regular intervals, commonly every four years, or every six years in hospitals. Requirements vary by province and by authority, so owners should confirm the applicable frequency.

A typical inspection and test of a fusible link fire damper involves:

1. Locating the damper and confirming access through the duct access door.
2. Inspecting the blades, frame, sleeve, link and springs for damage, corrosion or obstruction.
3. Removing or releasing the fusible link and confirming the damper closes fully and latches.
4. Resetting the damper and reinstalling the link.
5. Recording the damper location, condition, test result and any deficiencies, often with photographs.

Motorized smoke and combination dampers are tested by operating them from the fire alarm or smoke control system and confirming full travel and correct end-switch indication.

Owners of large buildings should maintain a damper inventory with locations on floor plans and access details. Without one, dampers are easily missed after renovations. Fire damper verification programs build this inventory and track deficiencies to correction.

Renovations

Renovations often disturb fire dampers: ducts are rerouted, ceilings closed over access doors, or new separations created without dampers. Any project that changes ductwork or fire separations should include a review of damper requirements and an inspection at completion.

Frequently asked questions

Can a fire damper be installed without an access door?

Generally no. Codes and listings require access for inspection and maintenance. Some products are designed for remote testing or access through a removable diffuser, but this must match the listing.

Are smoke detectors in ducts the same as smoke dampers?

No. Duct smoke detectors sense smoke and send a signal, typically to shut down a fan or close dampers. A smoke damper is the device that physically blocks the duct.

Key takeaways

• Fire dampers, smoke dampers and fire stop flaps each have a distinct role and Canadian ULC standard.
• Fire dampers are required at most duct penetrations of rated fire separations, with specific exceptions.
• Performance depends on installation matching the listing, including sleeves, retaining angles, clearances and access.
• Fire alarm and smoke control interactions must be documented and verified in integrated testing.
• Fire codes require dampers to be maintained, with periodic inspection and testing set by the authority.