When is a fire damper required in ductwork in Australia?

A fire damper is required wherever a duct penetrates a fire-rated wall or floor. NCC 2025 C4D15 requires protection of these openings, and AS 1668.1:2015 specifies that fire dampers complying with AS 1682 must be installed at these penetrations.

What is the 2-metre rigid duct rule for fire dampers?

Under AS 1668.1:2015 Clause 3.2.3, a wall-mounted fire damper must match the insulation rating of the wall it penetrates, unless it is connected to 2 metres of rigid steel duct on each side. Intumescent fire dampers can meet the insulation requirement without the 2m duct run.

What is the difference between a fire damper and a smoke damper?

A fire damper closes automatically when it detects heat (via a fusible link at about 72 degrees C) to stop flames spreading through ducts. A smoke damper is motorised, controlled by a smoke detection system under AS 1670.1, and closes to stop smoke spreading. Combination fire/smoke dampers do both jobs in one unit.

How often must fire dampers be inspected under AS 1851?

AS 1851 Clause 13.4.1.4 requires 20% of all fire and smoke dampers in a building to be inspected each year, so every damper is checked within a 5-year cycle. If 10-20% of inspected dampers fail, all dampers in the building must be inspected within 12 months.

What Australian Standard covers fire damper installation?

AS 1682.2:2015 covers the selection, installation and commissioning of fire, smoke and air dampers. AS 1682.1:2015 covers design, testing and marking. Both are referenced by AS 1668.1:2015 and the NCC 2025.

Fire Damper and Smoke Damper Requirements

Section 1

What You Need to Know

Fire dampers and smoke dampers stop fire and smoke from spreading through ductwork. Every duct that passes through a fire-rated wall or floor needs protection. AS 1682 (the Australian Standard for fire and smoke dampers) and AS 1668.1 (fire and smoke control in buildings) set the rules. Miss a damper or install it wrong, and the fire compartment fails.

Section 2

The Rules

Every duct penetration through a fire-rated wall or floor must be protected with a fire damper or tested system (NCC 2025, C4D15 and Specification S5C11)
All fire and smoke dampers must comply with AS 1682.1:2015 for design and testing, and AS 1682.2:2015 for installation and commissioning (AS 1668.1:2015, Cl 3.2)
Wall-mounted fire dampers must match the insulation rating of the wall, unless connected to 2 metres of rigid duct on each side (AS 1668.1:2015, Cl 3.2.3)
Smoke dampers must be installed within 600 mm of the smoke wall (AS 1668.1:2015)
Fire dampers must be tested to AS 1530.4:2014 for integrity and insulation performance (AS 1682.1:2015)
All fire and smoke dampers must be inspected under AS 1851, with 20% of dampers checked each year on a rolling 5-year cycle (AS 1851, Cl 13.4.1.4)

Section 3

What This Means in Practice

Picture a mechanical riser in a 10-storey office building. Ductwork runs vertically through the shaft, with branch ducts breaking out at each level through fire-rated floors. Every one of those floor penetrations needs a fire damper. If a smoke control system also serves those floors, you need smoke dampers too, or combination fire/smoke dampers that do both jobs in one unit.

The 2-metre rigid duct rule catches many projects. A fire damper on its own does not always meet the wall's insulation rating. You either run 2 metres of rigid steel duct from the damper on each side, or you use an intumescent fire damper that swells shut in heat and meets the insulation requirement without the extra ductwork. On tight sites with limited ceiling void, the intumescent option saves space.

Access is the other big issue. AS 1851 requires ongoing inspection, and inspectors need to reach every damper. If a damper is buried above a plasterboard ceiling with no access panel, it cannot be maintained. That puts the building out of compliance. Plan access panels into the ceiling layout from the start.

Section 4

Key Design Decisions

1

Damper Type: Mechanical, Intumescent, or Combination?

Use mechanical (curtain-type) fire dampers for standard duct penetrations where 2 metres of rigid duct is available. Pick intumescent dampers where space is tight or rigid duct lengths cannot be achieved. Use combination fire/smoke dampers at penetrations that need both fire resistance and smoke control.

Trade-off: Combination dampers typically cost more per unit than fire-only dampers, but they reduce the total number of devices and simplify coordination.

2

The 2-Metre Rigid Duct Rule

Where a fire damper does not match the wall's insulation rating, connect it to 2 metres of rigid steel duct on each side of the penetration. If this is not possible, specify an intumescent fire damper or fire-rated duct wrap (e.g. FyreWrap) to meet the insulation requirement.

Trade-off: Rigid duct adds length, weight, and ceiling void demand. Intumescent dampers cost more upfront but save space.

3

Access Panel Locations

Coordinate access panels for every fire and smoke damper during the design phase. Access panels must be large enough for inspection and must not compromise the fire rating of the ceiling or wall.

Trade-off: More access panels mean more coordination with the ceiling contractor, but without them the building fails AS 1851 maintenance audits.

4

Smoke Damper Control Strategy

Connect smoke dampers to the fire detection system (AS 1670.1) and, where required, to the fire command panel. Smoke dampers are always motorised and must respond to real-time signals.

Trade-off: Adds wiring, BMS integration, and commissioning time. Without it, the smoke control system does not function.

Section 5

Who Needs to Know What

Section 6

References

AS 1682.1:2015, Fire, smoke and air dampers — Part 1: Design, testing and marking
AS 1682.2:2015, Fire, smoke and air dampers — Part 2: Selection, installation and commissioning
AS/NZS 1668.1:2015, The use of ventilation and airconditioning in buildings — Part 1: Fire and smoke control in buildings
National Construction Code 2022, Volume One, Part C4 — Protection of openings (C4D15, Specification S5C11)
AS 1530.4:2014, Methods for fire tests on building materials, components and structures — Part 4: Fire-resistance tests for elements of construction
AS 1851-2012, Routine service of fire protection systems and equipment (Section 13 - Fire and smoke dampers)
AIRAH DA06, Guide to Fire, Smoke and Air Dampers

Fire Damper and Smoke Damper Requirements

What You Need to Know

The Rules

What This Means in Practice

Key Design Decisions

Damper Type: Mechanical, Intumescent, or Combination?

The 2-Metre Rigid Duct Rule

Access Panel Locations

Smoke Damper Control Strategy

Who Needs to Know What

Need this engineered for your project?

References

Related design memos

Smoke and Fire Damper Testing After Installation

Fire Rated Ceilings and Service Penetrations

Fire Resistance Levels and Service Penetrations