Certification mark: Label or plug on the top edge
Engineered core: The mass that resists fire
Hardwood lipping: Protects and trues the edge
Closing edge: ≈ 3 mm gap to the frame
Bottom edge: Up to ≈ 8 mm, less on a smoke door

Fire-resisting leafDrag to rotate · click a marker

Door leaf

The leaf is the mass of the fire door. The core chars slowly and holds the barrier; everything else on this page keeps it sealed, closed and in place. The rating belongs to the tested fire door, not the leaf alone. This model is a timber leaf, the most common type in UK buildings. Fire doors are also made in steel, glass and composite, and hardware proven on timber does not transfer to them.

Key facts

Function: Holds back fire and smoke as the main body of the fire door
Specification: Nominal 44 mm for FD30, nominal 54 mm for FD60
Materials: Core of particleboard, solid or laminated timber, flaxboard or mineral, usually lipped on the edges, commonly in hardwood
Critical tolerances: About 3 mm to the frame at head and jambs; trim only within the margin the certificate allows
Standards: Tested to BS EN 1634-1 or BS 476-22. Installed to BS 8214
Role in fire: Provides the fire resistance the FD rating is named for: 30 or 60 minutes of integrity

ComplianceThe certificate covers the fire door as tested. Trimming past the permitted margin, cutting a new aperture or swapping a component takes the door outside it. BS 8214 is the code of practice for installing timber fire doors and is what an installation is judged against.

Did you knowTimber does not give way suddenly. It chars inward at a rate that can be measured, and the char layer insulates the sound timber beneath it. That is why a heavy timber leaf can hold for 30 minutes while an unprotected steel section is already deforming.

In the fire door

Where it sits

Inspection focus

What inspectors check

Locate the certification label or plug: usually the top edge, sometimes the hanging edge
Measure perimeter gaps, about 3 mm at head and jambs
Look over both faces and all four edges for impact damage and splits
Sight down the leaf for bow or twist

Extended knowledge

Go deeper

Certification label or plug missing
Planed down beyond the permitted margin
Impact damage, splits or gouges in the face or edges
Holes or unfilled fixings through the leaf

Test yourself

5 questions

What is the nominal leaf thickness of an FD30 fire door?

UK Fire Door Training presents

The UK’s firstinteractive fire dooranatomy.

A certified fire door, opened component by component, in three dimensions. Built by UK Fire Door Training and free to the entire industry.

An educational resource for the industry. No sign-up, no paywall.