What Are the Components of a Fire Door?

Fire doors are one of the most effective tools for slowing the spread of fire and smoke, protecting escape routes and saving lives.

But a fire door is much more than just a heavy wooden door—it’s a carefully engineered safety system made up of several components, all working together to perform under extreme conditions.

In this guide, we’ll break down the key components that make up a compliant fire door, and why each part matters when it comes to fire protection.

1. The Door Leaf

The door leaf is the main part of the fire door—the actual slab that opens and closes. Unlike standard doors, fire door leaves are made from fire-resisting materials such as:

• Solid timber cores
• Composite cores with layers of fireboard or particleboard
• Mineral-based materials for higher fire ratings

Each door leaf is tested and certified to resist fire for a specific amount of time—usually FD30 (30 minutes) or FD60 (60 minutes). It’s vital that the certification label or plug is present and matches your building’s fire strategy.

2. The Fire Door Frame

The frame holds the door leaf in place and must also be constructed from fire-rated materials, such as hardwood or steel, depending on the door’s rating.

A compliant fire door frame:

• Must be installed to tight tolerances, with minimal gaps
• Should be properly sealed to surrounding walls
• Must be compatible with the fire door leaf as per manufacturer’s instructions

Even a correctly rated door leaf won’t be effective if the frame is substandard or poorly fitted.

3. Intumescent Seals

Intumescent seals are fitted into the edges of the door leaf or frame.

When exposed to high temperatures during a fire, these seals expand to many times their original size, filling the gap between the door and frame to stop flames and smoke from passing through.

Some seals are combined with cold smoke seals, which stop smoke leakage before temperatures rise.

Seals must:

• Be continuous and undamaged
• Match the manufacturer’s specification
• Be replaced if painted over, split or missing

Missing or worn intumescent strips are a common reason fire doors fail inspections.

4. Hinges

Fire doors must be hung on at least three fire-rated hinges, which are:

• Made of steel or other fire-resisting material
• Marked as CE-compliant
• Fixed using appropriate screws (usually steel, with a minimum of four per hinge)

Hinges must not be loose, damaged or painted over, as this can compromise their function in a fire.

5. Door Closers

Most fire doors are fitted with an automatic door closer—a device that ensures the door returns to the closed position after being opened.

This is vital, because a fire door that’s left open is useless in a fire.

Closers must:

• Fully close the door without slamming
• Be adjusted correctly so the door latches securely
• Be regularly checked as part of maintenance routines

Where accessibility is a concern (such as for disabled access), electromagnetic hold-open closers may be used, which release automatically when the fire alarm sounds.

6. Latches and Locks

Any latches, locks, or panic bars fitted to a fire door must:

• Be fire-rated
• Not prevent the door from closing securely
• Be suitable for escape routes (e.g. simple push bars in public spaces)

Locks and latches should not interfere with the door’s closing action, and keyless egress is usually required on exit doors.

7. Glazing and Vision Panels (if present)

Many fire doors have glazed panels, allowing visibility while maintaining fire resistance. These panels must:

• Be made of fire-resistant glass, tested to the same rating as the door
• Be fitted using fire-rated glazing systems
• Have appropriate seals and fixings

Poorly fitted or cracked glazing invalidates the fire rating.

8. Signage

Every fire door should have:

• A blue circular “Fire Door Keep Shut” sign (or “Keep Locked” or “Automatic Fire Door Keep Clear” as appropriate)
• Signage must be clearly visible, durable, and correctly placed

This is a legal requirement under the Health and Safety (Safety Signs and Signals) Regulations 1996 and helps staff and the public understand their responsibilities.

Why All Components Matter

Fire doors are only effective if all components work together as an integrated system.

Mixing and matching uncertified parts, or replacing damaged items without using fire-rated equivalents, undermines the whole purpose of the door.

At ESI, we regularly see issues like:

• Missing seals
• Damaged closers
• Oversized gaps
• Incompatible hardware
• Uncertified replacements

Each of these issues puts people at risk—and may result in failure during a fire inspection or audit.

Need Help Checking Your Fire Doors?

At ESI: Electrical Safety Inspections, we help building owners, landlords, schools, housing providers and commercial sites across Farnborough, Camberley, Reading, Guildford, and the wider Surrey, Hampshire and Berkshire region.

Our team can:

• Inspect your fire doors for compliance
• Identify missing or incorrect components
• Recommend repairs or replacements
• Help you meet your legal obligations under the Fire Safety Order

If you’re unsure whether your fire doors are compliant, let’s have a chat.

Get in touch with ESI today for professional fire door inspections and peace of mind.