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.
In This Guide
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
Fan shutdown systemsStatic 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
Fans keep runningDynamic 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
Fire + smoke controlCombination 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
Passive — no moving partsWhere 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 (from £79.99) and square intumescent fire blocks from 150mm to 600mm (from £40.76). All are 38mm deep with approximately 60% free area. View the 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.
| Fire Damper | Smoke Damper | Combination | |
|---|---|---|---|
| Purpose | Prevents spread of fire through duct penetrations | Prevents spread of smoke through ductwork | Both |
| Trigger | Heat (fusible link at 72°C or fire alarm signal) | Smoke detection signal | Both heat and smoke detection |
| Test standard | BS EN 1366-2 | BS EN 1366-10 | Both standards |
| When it activates | When temperature reaches fusible link's melting point | As soon as smoke is detected — much earlier | Whichever trigger occurs first |
| Reset | Replace fusible link (or reset actuator) | Reset from BMS | Reset from BMS |
| Typical use | Any duct penetrating a fire barrier | Smoke extract/pressurisation systems | Most modern commercial buildings |
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. EN 15650 is the harmonised product standard and EN 1366-2 is the test method beneath it, so the two are complementary rather than alternatives. Check that any fire damper you specify carries a valid declaration of performance.
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
| When | What | Notes |
|---|---|---|
| On installation | Full operational test | Must be tested before building is occupied |
| Annually (minimum) | Visual inspection + drop test | BS 9999 requirement for all fire dampers |
| Six-monthly | Full inspection + test | Recommended for hospitals, care homes, HMOs. Often required by insurers |
| At each fire alarm test | Actuator response check | Motorised dampers only — verify BMS signal triggers closure |
What a Fire Damper Test (Drop Test) Involves
- Visual inspection: Check the damper is accessible, the access panel is in place, and there's no visible damage, corrosion, or obstruction.
- Operational test: Release the fusible link (or trigger the actuator) to confirm the blade closes fully and completely seals the duct opening.
- Reset: For resettable dampers, reset the blade and confirm it locks back into the open position. For fusible-link-only dampers, replace the link.
- 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
| Product | Type | Sizes | Stated performance | Resettable | Price From |
|---|---|---|---|---|---|
| BSB FD-C Series | Circular mechanical | 100–315mm | ES to BS EN 1366-2, EN 1751, EN 1506 | Yes (external) | £103.68 |
| Systemair PKI Range | Circular mechanical | 100–315mm | EIS to EN 1366-2, up to 120 min, 72°C fuse | Yes | £58.06 |
| Air Valve with Fire Damper | Combined valve + fire damper | 100–160mm | CE marked to EN 15650 | N/A (intumescent) | £94.59 |
| Circular Intumescent Block | Passive intumescent | 100–200mm | Manufacturer: up to 120 min walls/ducts | No (single use) | £79.99 |
| Square Intumescent Block | Passive intumescent | 150–600mm | Manufacturer: up to 120 min walls/ducts | No (single use) | £40.76 |
View all 17 fire damper products →
Choosing the Right Fire Damper
When specifying, work through these factors:
- 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.
- Static or dynamic: Will the HVAC system shut down during a fire (static) or continue running for smoke extract (dynamic)?
- Fire only or fire and smoke: Does the fire strategy require smoke control? If so, specify a combination fire/smoke damper.
- Duct shape and size: Match the damper to the duct diameter at the point of penetration.
- Reset method: Externally resettable dampers (like the BSB FD-C) save significant time during annual testing.
- Actuator type: Fusible link (simpler, cheaper, no power needed) or motorised (faster response, BMS integration)?
Need help specifying? Email hello@efans.co.uk or call 0161 399 3825 and we can help you choose the right damper for your ductwork and fire rating requirements.
Shop Fire Dampers at eFans
Trade pricing available on account, and we can quote against a full schedule. Certification differs by product type, so check the individual product page for the standard that applies.
Browse all 17 fire damper products →
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 for general HVAC fire dampers in the UK. Some specialist applications use links rated at 100°C or higher.
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.
Can I use an intumescent fire block instead of a fire damper?
Not interchangeably. An intumescent block is a passive air transfer product with no moving parts and no classification under a harmonised damper standard. It suits door transfer grilles, wall openings and room terminals. Where the fire strategy or specification calls for a classified mechanical fire damper at a duct penetration, a block will not satisfy it. If you are unsure which your project needs, call us and we will go through it rather than guess.
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: September 2026. Prices shown are from eFans at the time of writing and include VAT. Certification varies by product type, so always check the individual product page and the fire strategy for your specific project. For specification advice, email hello@efans.co.uk or call 0161 399 3825.