What is the difference between a fire door and a standard door?
A fire door is tested as a complete doorset, with leaf, frame, seals, hinges and closer all working together to hold back fire for a set time. A standard door has no fire test and no rating. Fire doors also close themselves, carry intumescent seals and keep tight gaps.
By Sebastian Grabowski, DC Fire & Security, Luton. Updated November 2026.
The difference is the whole doorset
People talk about a fire door as if it were a type of leaf. It is better to think of it as a kit of parts that has been through a fire test together. Approved Document B asks that the test evidence applies to the complete installed assembly, because small changes in detail can affect the result. A solid, heavy door on its own is not a fire door.
A standard internal door may burn through, warp or let smoke past in minutes. Nobody has measured how long, because it was never designed or tested to do that job.
What is different, part by part
| Part | Fire door | Standard door |
|---|---|---|
| Test evidence | Tested as a doorset, with a rating such as FD30 or FD30S | None |
| Leaf | Built to the tested design, often heavier and denser | Usually lighter, often hollow or thin panelled |
| Frame | Matched to the leaf and fixed as tested | Any frame |
| Intumescent seals | Fitted in the leaf or frame edge, swelling in heat to close the gap | Not fitted |
| Smoke seals | Fitted on FD30S and similar doors | Not fitted |
| Self-closing device | Fitted, so the door shuts after every use | Often none |
| Hinges | Fire rated, usually three | Any hinges, often two |
| Gaps | Tight and even, with the door fully closing | Not controlled |
| Glazing and letterbox | Fire rated if fitted at all | Ordinary glass and plastic |
| Label or plug | Often marked or certified | Never |
Why panelled doors are a problem
Older flats and houses often have panelled doors that look sturdy. The thin timber panels burn through quickly and the rating of the original design is lost. Painting over the wood and adding strips does not turn it into a fire door either. If you have a panelled door where a fire door is needed, we advise replacing it with a plain certified doorset. See fire rated doorsets.
Where you need which
Fire doors are used where the building relies on a fire door to separate parts of it or protect an escape route. Examples are doors between a flat and a shared corridor, doors to stairways and plant rooms, and doors to risers. An ordinary door is fine in a room where no fire door is required, for example inside a flat. The fire risk assessment or the fire strategy says which is which.
How to tell one from the other
Look for a label or plug on the hinge edge or top, intumescent or smoke seals around the leaf or frame, a closer, three hinges and a heavy feel. None of these alone proves it, and missing ones do not always mean a failed door. Our guide on how to identify a fire door covers each check. If you want to know what you have in a building, an inspection will record each door with photographs. For a replacement, see fire door installation.
Frequently Asked Questions
Is a fire door just a heavier door?
Can I turn an ordinary door into a fire door?
Do fire doors have to be self-closing?
Does a fire door stop all smoke?
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Email your report or photos to info@dcsecurity.co.uk, or use the form. We usually come back with a fixed price the same day. Luton, Bedfordshire, Hertfordshire, Buckinghamshire and London.
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