Fire doors: the basics
A fire door holds back fire and smoke for a set time so people can get out and firefighters can get in. It only works when it's closed, undamaged and fitted as it was tested.
Last reviewed October 2026. General information, not legal advice.
What a fire door is for
Buildings are split into sections that resist fire. Walls and floors do most of the work, and fire doors close the gaps where people need to pass through. When a door is shut, it slows the spread of fire and smoke along corridors and stairs, which are usually the escape routes.
A fire door standing open, or one that doesn’t close fully, protects nothing.
How to tell if a door is a fire door
Look for:
- A label or coloured plug, often on the top or hinge edge of the door
- Strips around the edge of the door or frame (intumescent strips, which swell in heat)
- A self-closer that pulls the door shut
- A “Fire door” sign
Your fire risk assessment or previous inspection records should also say which doors are fire doors. If in doubt, ask an inspector.
FD30, FD60 and the S
| Rating | What it means |
|---|---|
| FD30 | Holds back fire for 30 minutes when closed |
| FD60 | Holds back fire for 60 minutes when closed |
| S suffix (e.g. FD30S) | Also limits the spread of smoke |
The rating each door needs is set by the building’s fire strategy and fire risk assessment, not by the door itself.
Why the whole door matters
A fire door is a tested set of parts: the door, frame, hinges, seals, closer, glass and any ironmongery. Swap one part for something untested, or cut a hole for a new lock or cable, and the door may no longer perform as it was tested. That’s why repairs and changes need care.
Next guide: Who is responsible for fire doors?