Fire doors are one of the most important safety features in any building, yet they are frequently misunderstood, poorly maintained, or taken for granted. Understanding what fire doors are, how they work, and why they matter could save lives in an emergency.

In this guide, we cover everything you need to know about fire doors, from materials and ratings to UK legal requirements and how long they last. As a British manufacturer of certified fire doorsets for over 25 years, Gerda Security knows this subject inside out.

 

What Are Fire Doors?

Fire doors are specially engineered doorsets designed to resist the spread of fire and smoke between compartments of a building. 

A fire door is a complete doorset, including the frame, door leaf, seals, hinges, door closer, and all associated hardware. Every component must be specified, tested, and installed correctly for the assembly to perform as rated.

The purpose of a fire door is to protect lives, preserve escape routes, and contain fire within a compartment for a set period.

Fire doors differ from standard doors in several ways: they have heavier construction, certified fire-resistant components, mandatory self-closing mechanisms, and must carry clearly visible labelling. They are easy to identify, too; just look for the ‘Fire Door Keep Shut’ or ‘Fire Door Keep Closed’ sign.

 

What Are Fire Doors Made of?

Fire doors are not made from a single material. They are engineered products, and it is the specific combination of materials used in their construction that determines their fire rating and performance.

Common core materials include: 

• Solid timber or engineered timber composites 
• Steel (used for higher ratings) 
• Gypsum or vermiculite boards (used as fire-resistant infill layers) 
• Wire mesh reinforcement (in glazed panels) 
• Fire-rated glass (for vision panels) 

Key Components of a Fire Door 

• Intumescent strips expand when exposed to heat, sealing the gap between the door and frame to prevent flame passage
• Smoke seals (fin or brush-type) prevent smoke migration in the early stages of a fire, before the intumescent strips activate
• Drop-down seal fitted at the bottom of the door, drops automatically when the latch closes, sealing the threshold gap without dragging on the floor during normal use
• Door closer ensures the door returns to the fully closed position after each use, which is essential for the door to perform its fire-containment function 
• Fire-rated hinges are designed to withstand the weight and heat stress of a fire event. A minimum of three certified hinges is required
• Intumescent lock and handle protection sits behind the hardware and expands under heat to maintain the door’s integrity around vulnerable penetration points
• Certification label found on the top or side edge of the door, confirming the doorset has been third-party tested and certified to the relevant British Standard, typically BS 476 Part 22 or BS EN 1634-1

Fire Door vs Standard Door: Key Difference

Feature	Fire Door	Standard Door
Self-closing mechanism	Required	Not required
Intumescent seals	Yes	No
Fire rating	FD30–FD240	None
Certification label	Mandatory	Not applicable
Minimum 3 hinges	Required	Not required

 

What Are Fire Doors Used for?

The primary use of fire doors is compartmentation. By subdividing a building into defined sections, fire doors help ensure that flames and smoke are contained within the compartment of origin and prevented from spreading rapidly throughout the building.

Fire doors also protect escape routes. Corridors, stairwells, and exit paths must remain safe and passable during an evacuation, and fire doors play a critical role in keeping those routes clear of smoke and flames.

By limiting fire and smoke damage to a single compartment, they also protect property and give the fire brigade additional time to respond and contain the incident.

Fire doors are not solely for emergencies. They are designed to be used as ordinary access doors throughout the day, while still performing their fire safety function each time they close.

 

Where Does Law Require Fire Doors in the UK?

Under the Regulatory Reform (Fire Safety) Order 2005 and the Fire Safety (England) Regulations 2022, fire doors are legally required in:

• Commercial premises and workplaces 
• Public buildings (hospitals, schools, government offices, and retail spaces) 
• Houses of multiple occupancy (HMOs) 
• Blocks of flats, including communal areas and flat entrance doors
• High-rise residential buildings (quarterly inspections legally required for communal fire doors) 

Note: Domestic dwellings of three or more storeys may also require fire doors between floors. If you are unsure what applies to your property, consult current Building Regulations or seek advice from a qualified fire safety professional.

 

How Do Fire Doors Work?

Fire doors do not put out fires. They contain them. Their function is entirely passive: protection is built into the materials, construction, and hardware of the doorset itself. Here is what happens when a fire breaks out:

1. Fire or heat is detected, triggering the fire alarm. Any electromagnetic hold-open device, which is a mechanism that keeps a fire door open during normal use and releases it automatically when the alarm sounds, disengages and allows the door to close.
2. The door closer draws the door fully into its frame, and the latch engages. A fire door that does not close completely provides no protection.
3. As temperatures rise, the intumescent strips fitted around the door perimeter activate, expanding to fill the gap between the door leaf and frame and forming a barrier through which flames cannot pass.
4. At the same time, smoke seals prevent the passage of smoke, which is often more immediately dangerous than the flames themselves.
5. The drop-down seal at the base of the door closes the threshold gap, preventing smoke from travelling under the door.
6. The door holds back fire and smoke for its rated period, whether that is 30, 60, 120, or 240 minutes, giving occupants time to escape and emergency services time to respond.

 

Fire Doors and Passive Fire Protection

Fire doors are just one component of a passive fire protection (PFP) strategy. Unlike active systems, passive fire protection does not rely on detection or intervention. It works through the physical properties of the building fabric itself, continuously and without any activation required.

A building’s passive fire protection relies on three elements working in combination:

• Fire-rated walls and floors that are correctly constructed
• Sealed penetrations and coatings built to the same standard as the surrounding structure
• Correctly rated fire doors, shutters, and barriers that are installed and regularly inspected

Active fire protection, such as sprinkler systems and fire detection alarms, is a separate but complementary layer of protection that is also typically required by law. Active systems detect and suppress fire, while passive systems contain it.

If you would like to discuss how certified fire doorsets fit into your building’s overall fire strategy, contact the Gerda Security team. 

 

Fire Door Ratings Explained: FD30, FD60, FD120, and FD240

The FD rating tells you how many minutes a certified fire door can resist fire under standardised test conditions. The higher the number, the longer the protection period.

FD30	FD60	FD120	FD240
30 minutes	60 minutes	120 minutes	240 minutes
The most common rating, used in the majority of commercial and residential buildings.	Used in higher-risk areas or where evacuation may take longer to complete.	Specified for high-risk commercial or industrial buildings.	The highest available rating, only achievable with steel construction.

 

FD30, FD60, and FD120 can be manufactured in timber or steel, but FD240 requires steel only. 

If you see an ‘S’ suffix on a fire door rating, for example, FD30S or FD60S, this indicates that smoke control is included within the door’s tested performance, in addition to fire resistance.

 

How Long Do Fire Doors Last?

There is no fixed legal lifespan for a fire door. How long it lasts depends on its condition, how often it is used, and how well it has been maintained. Fire doors remain effective for as long as they are correctly installed, regularly inspected, and properly maintained. Once any critical component fails, the door’s rated performance can no longer be relied upon.

Under the Regulatory Reform (Fire Safety) Order 2005, building owners and Responsible Persons must ensure that fire doors maintain their fire resistance over time. The Fire Safety (England) Regulations 2022 introduced specific additional requirements:

• Quarterly inspections of fire-resisting doors in communal areas of residential buildings above 11 metres in height
• Annual checks of fire-resisting entrance doorsets to individual flats, on a best-endeavours basis
• Provision of information to residents on the importance of fire doors, self-closing devices, and reporting faults

As a general guide, fire doors should be inspected at a minimum every six months. Doors on busy corridors or stairwells may need to be inspected more often.

 

Signs a fire door may need replacing or remediation

If any of the following are present, the door should be assessed by a competent professional:

• Gaps around the frame exceeding the manufacturer’s test limit
• Damaged or missing intumescent/smoke seals 
• Door not closing fully or latching 
• Damaged hinges or missing screws 
• Bowed, warped, or cupped door leaf 
• Absence of a certification label 

Full replacement is not always necessary. In many cases, damaged or degraded components can be replaced or repaired by a qualified professional, provided the original doorset specification is followed, and the work is carried out in line with the manufacturer’s instructions.

 

Frequently Asked Questions

What’s the difference between FD30 and FD60?

FD30 doors resist fire for 30 minutes, while FD60 doors resist fire for 60 minutes. The right choice depends on your building type, the level of risk, and applicable regulations. If you are unsure which rating applies to your building, consult a qualified fire safety professional or refer to Approved Document B of the Building Regulations.

 

Can a fire door be left open?

No. A fire door must be kept closed at all times or held open only by a certified electromagnetic hold-open device linked to the building’s fire alarm system. When the alarm activates, the device releases and the door closes automatically. Propping a fire door open with a wedge or any other object removes all protection and may breach fire safety legislation under the Regulatory Reform (Fire Safety) Order 2005.

 

How can I tell if a door is a certified fire door?

Look for a certification label on the top edge or side of the door, or a coloured plug within the door leaf. The label confirms it has been third-party tested and meets fire safety standards. If no label is present, the door cannot be verified as a certified fire door regardless of its age or appearance.

 

Do fire doors need to be installed by a professional?

Yes. A competent person must install a fire door in accordance with the manufacturer’s specification and relevant standards. Incorrect installation can compromise the door’s rating and may invalidate its certification. 

 

What is the difference between a fire door and a fire exit door?

A fire door is designed to contain fire and smoke between compartments within a building. A fire exit door is designed to allow rapid egress and typically opens outward, fitted with push-bar hardware. 

The two serve different purposes. In some locations, a doorset must fulfil both functions simultaneously, which requires a specific specification. If in doubt, consult a fire safety specialist.

 

How often should fire doors be inspected?

Fire doors should be inspected at least every six months, and more frequently for high-use doors. Under the Fire Safety (England) Regulations 2022, buildings above 11 metres in height are subject to quarterly inspection requirements for communal fire doors. All inspections must be carried out by a competent person.

Do fire doors work without a door closer?

No. A fire door must be fully closed to contain fire and smoke. Without a working door closer, there is no guarantee the door will be shut when a fire breaks out. A correctly specified door closer is a mandatory component of every fire doorset. If a door closer is missing, damaged, or has been removed, the door is not compliant.