Fire Dampers: The Complete UK Guide to Types, Regulations & Testing

In any building with ducted ventilation, the ductwork creates a hidden network of pathways running through walls and floors. If a fire starts, those same pathways can carry flames and toxic smoke from one part of the building to another in minutes. Fire dampers prevent that — they're devices fitted inside the ductwork that automatically slam shut when they detect a fire, sealing off the ducts and stopping fire from spreading.

If you're working on a commercial or industrial building in the UK, fire dampers aren't optional — they're a legal requirement under Building Regulations Approved Document B. But fire dampers are only part of the picture. Smoke dampers, combination fire/smoke dampers, and intumescent fire blocks all play different roles in keeping a building's fire compartments intact.

This guide covers how each type works, what the UK regulations require, how to maintain and test them, and how to choose the right product for your project — whether you're a contractor specifying a new build, a facilities manager organising annual testing, or just getting your head around fire safety requirements for the first time.

How Does a Fire Damper Work?

A fire damper sits inside the ductwork, usually at the point where a duct passes through a fire-rated wall or floor. In normal operation, the damper blades are held open and air flows through freely — you wouldn't know it was there.

The clever part is the trigger mechanism. Most fire dampers use a fusible link — a small metal component that melts at a set temperature, usually 72°C. When a fire heats the air inside the duct to that point, the link melts, releasing a spring that snaps the damper blades shut. The duct is sealed, and fire can't travel through it to the next room, floor, or fire compartment (the term for a section of a building designed to contain fire for a set period).

Some modern fire dampers use motorised actuators instead of fusible links. Rather than waiting for heat to melt a link, these connect to the building's fire alarm system and close when they receive an electrical signal — so they can respond faster and they're much easier to test. Motorised dampers are increasingly specified in new-build commercial projects, particularly where a building management system (BMS) is controlling the ventilation.

Types of Fire Damper

Not all fire dampers work the same way. The type you need depends on your ventilation system and the level of fire and smoke protection required.

Static Fire Dampers

Static fire dampers are designed for ventilation systems where the fans shut down when the fire alarm goes off. When the fusible link melts, a curtain-style blade drops closed under gravity. Because the fan has stopped, there's no airflow pushing against the damper — it just falls shut.

These are the most common type in smaller commercial buildings and simpler ventilation setups where the strategy is: fire alarm triggers, fans stop, dampers close.

Dynamic Fire Dampers

Dynamic fire dampers are built for systems where the fans keep running during a fire — for example, in smoke extraction systems that actively pull smoke out of the building. They use spring-loaded blades that close against the airflow, and the continued air pressure actually helps keep the blades firmly shut.

You'll typically find these in more complex HVAC systems — particularly in larger buildings with dedicated smoke ventilation strategies where maintaining airflow in certain zones is part of the fire safety design.

Combination Fire and Smoke Dampers

Combination fire/smoke dampers do both jobs: they block fire and prevent cold smoke from spreading through ductwork before temperatures rise enough to trigger a standard fusible-link fire damper. They use a motorised actuator linked to smoke detectors, which means they can close in response to smoke detection — not just heat.

Most modern commercial buildings — particularly offices, healthcare facilities, and residential blocks — now require combination dampers to meet current fire safety standards.

Intumescent Fire Blocks

Where ducts pass through fire-rated walls but a traditional mechanical fire damper isn't practical — for example, in smaller openings, passive air transfer grilles, or where ducts terminate at supply/extract terminals — intumescent fire blocks provide an alternative. ("Intumescent" just means the material swells when heated.)

These blocks contain material that expands rapidly when exposed to heat, crushing and sealing the duct or opening. They're completely passive — no moving parts, no fusible links, no actuators — which makes them virtually maintenance-free. Commonly used on individual room supply and extract terminals of MVHR (mechanical ventilation with heat recovery) and MEV systems, particularly in residential blocks of flats.

We stock circular intumescent fire blocks from 100mm to 200mm and square intumescent fire blocks from 150mm to 600mm, all with EI120 fire ratings. View our full range →

Fire Dampers vs Smoke Dampers: What's the Difference?

These two get confused a lot, but they do different jobs and respond to different things. Getting the distinction right matters when you're specifying a system — using the wrong type can leave gaps in your fire safety.

In practice, many modern installations use combination fire and smoke dampers that satisfy both requirements in a single unit. This simplifies installation and reduces the number of devices in the ductwork.

UK Fire Damper Regulations

Fire damper installation in the UK is governed by several overlapping standards and regulations. If you're specifying, installing, or maintaining fire dampers, these are the ones that matter.

Building Regulations Approved Document B

The primary regulatory document. Approved Document B (Fire Safety) requires that fire dampers are installed wherever ductwork penetrates a fire compartment wall or floor. The damper must maintain the fire resistance rating of the barrier it passes through — so a duct going through a 2-hour fire-rated wall needs a damper rated at least EI120.

BS 9999:2017 — Fire Safety in Buildings

Sets out minimum requirements for fire damper inspection, testing, and maintenance:

• Tested by a competent person on completion of installation
• Inspected and tested at least annually thereafter
• Accessible for inspection and maintenance at all times

BS EN 1366-2 — Fire Resistance Testing

Defines the test methods for fire damper fire resistance. Products are classified by integrity (E) and insulation (I) — for example, EI120 means the damper maintains both integrity and insulation for 120 minutes.

BS EN 15650 — Classification and Marking

Covers classification, designation, and product marking. Check that any fire damper you specify carries a valid BS EN 15650 declaration of performance. All fire dampers we stock at eFans are certified to this standard.

BS EN 1366-10 — Smoke Dampers

The relevant test standard for the smoke control function of smoke dampers and combination fire/smoke dampers. Tests the damper's ability to prevent the passage of cold and hot smoke through ductwork.

Where Should Fire Dampers Be Installed?

Fire dampers are required at every point where ductwork crosses a fire compartment boundary:

• Fire-rated walls — any wall separating fire compartments, including party walls in residential blocks
• Floor penetrations — where vertical risers pass between floors
• Ceiling voids — where ducts pass through fire barriers above suspended ceilings
• Plant room boundaries — separating mechanical spaces from occupied areas
• Escape route boundaries — protecting corridors and stairwells

Fire Damper Testing and Maintenance

A fire damper that's seized, blocked, or has a corroded fusible link won't close when it needs to — and you won't know until it's tested or there's a fire. Regular testing isn't optional; it's a legal requirement under BS 9999, and it's one of the most common things that catches building owners out during fire risk assessments.

Testing Frequency

What a Fire Damper Test (Drop Test) Involves

1. Visual inspection: Check the damper is accessible, the access panel is in place, and there's no visible damage, corrosion, or obstruction.
2. Operational test: Release the fusible link (or trigger the actuator) to confirm the blade closes fully and completely seals the duct opening.
3. Reset: For resettable dampers, reset the blade and confirm it locks back into the open position. For fusible-link-only dampers, replace the link.
4. Record keeping: Document the date, damper location, test result, and the name of the person who carried out the inspection.

Common Maintenance Issues

The most frequent problems found during fire damper inspections:

• No access panel: The single most common issue. Dampers installed above fixed ceilings with no way to reach them for testing are non-compliant from day one. Plan access at design stage.
• Blade obstruction: Building debris, insulation, or duct sealant preventing the blade from closing fully.
• Corroded fusible links: Particularly in humid environments — kitchens, swimming pools, laundries.
• Painted-over dampers: Decorators painting over access panels or the damper mechanism itself during refurbishment.
• Missing fire stopping: The damper is installed but the gap between the damper sleeve and the wall/floor hasn't been properly fire-stopped.

Product Comparison Table

View all 16 fire damper products →

Choosing the Right Fire Damper

For standard circular ductwork in commercial buildings: The BSB FD-C Series (from £96.35) is our most popular fire damper. It's externally resettable — saving significant time during annual testing — and doubles as a volume control damper. EI120 rated, certified to BS EN 15650.

For MVHR and MEV room terminals: The FlaktWoods Air Valve with Fire Damper (from £81.34) combines a standard adjustable air valve with an intumescent collar. One unit gives you airflow control and fire protection at every room terminal — particularly useful in residential blocks of flats. Tested to EN 1366-2.

For passive air transfer openings: Intumescent fire blocks (from £40.76) are the simplest and most cost-effective option for non-ducted openings between rooms. No moving parts, no maintenance, EI120 rated. Available in circular (100–200mm) and square (150–600mm).

For the best value circular fire damper: The Systemair PKI Range (from £53.63) is a straightforward in-duct circular fire damper. Reliable, competitively priced, and covers all standard circular duct sizes.

When specifying, work through these factors:

1. Fire rating required: Match the damper's EI rating to the fire resistance of the barrier. 60-minute wall = minimum EI60. 120-minute wall = EI120.
2. Static or dynamic: Will the HVAC system shut down during a fire (static) or continue running for smoke extract (dynamic)?
3. Fire only or fire and smoke: Does the fire strategy require smoke control? If so, specify a combination fire/smoke damper.
4. Duct shape and size: Match the damper to the duct diameter at the point of penetration.
5. Reset method: Externally resettable dampers (like the BSB FD-C) save significant time during annual testing.
6. Actuator type: Fusible link (simpler, cheaper, no power needed) or motorised (faster response, BMS integration)?

Need help specifying? Get in touch — we can help you choose the right damper for your ductwork and fire rating requirements.

Shop Fire Dampers at eFans

All products in stock with next-day delivery. Trade pricing available. Certified to BS EN 15650.

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Frequently Asked Questions

What temperature does a fire damper activate?

Most fusible-link fire dampers activate at 72°C, which is the standard trigger temperature specified in BS EN 15650. Some specialist applications use links rated at 100°C or higher, but 72°C is the default for general HVAC fire dampers in the UK.

Can I use a fire damper instead of a smoke damper?

No — a standard fire damper only responds to heat, not smoke. If your building's fire strategy requires smoke control through the ductwork, you need either a dedicated smoke damper or a combination fire/smoke damper. A fire damper alone will not activate until temperatures reach 72°C, by which time smoke may have been circulating for several minutes.

Do residential buildings need fire dampers?

Yes, if there's ducted ventilation passing through fire compartment walls or floors. This is particularly relevant in blocks of flats where communal ventilation risers penetrate the fire separation between individual flats. Approved Document B requires fire dampers or intumescent fire blocks at every compartment boundary penetration.

Who can test fire dampers?

BS 9999 requires testing by a competent person. This doesn't necessarily mean a specialist contractor — a trained in-house facilities team can carry out routine inspections — but they must understand the procedure, know what constitutes a pass or fail, and be able to properly record the results. For complex installations or motorised dampers linked to BMS, a specialist fire damper testing contractor is recommended.

What happens if a fire damper fails its annual test?

A failed fire damper must be repaired or replaced as a matter of urgency. It's a breach of fire compartmentation, which could allow fire and smoke to spread to other parts of the building. The failure should be recorded, the responsible person notified immediately, and a remedial action plan put in place. In some cases, interim measures such as fire watch patrols may be needed until the damper is operational.

What's the difference between EI60, EI90, and EI120 fire ratings?

The numbers refer to the time in minutes that the damper maintains both integrity (E) and insulation (I) during a fire. EI60 = 60 minutes, EI90 = 90 minutes, EI120 = 120 minutes. The damper's rating must match or exceed the fire resistance of the wall or floor it's installed in. Most commercial applications require EI120 for walls and EI60 or EI90 for floors, but always check the fire strategy for your specific building.

Last updated: April 2026. Prices shown are from eFans at the time of writing and include VAT where stated. Always check the fire strategy and Building Regulations for your specific project. For specification advice, contact our team.