How to Identify a Fire Door: Labels, Plugs and What FD30 Means
By the DC Fire & Security engineering team — installing and maintaining fire and security systems since 2010. Updated June 2026.
Quick answer
Look at the top edge of the door (open it and look up): certified fire doors carry a label, coloured plug or stamp from schemes like BWF-Certifire, BM TRADA Q-Mark or FIRAS, stating the rating — FD30 means 30 minutes' fire resistance, FD60 sixty. Supporting clues: intumescent strips in the edges, three hinges, a closer, and 'Fire door keep shut' signage. No marking means performance can't be proven.
Where the evidence lives
- Top edge: labels and stamps survive here because nobody paints it — bring a torch and a mirror (or phone camera held above the leaf)
- Hinge edge: BM TRADA plastic plugs (colour-coded) are often set into this edge
- Labels state: certification scheme, manufacturer, rating (FD30/FD60), and often a unique number traceable to the test evidence
- Secondary indicators (not proof): 44mm+ leaf thickness (54mm for FD60), noticeably heavy, intumescent grooves/seals, three hinges, self-closer, fire-rated glazing stamps in any vision panel
- Frames matter too: a certified leaf in a non-fire frame is not a fire door assembly — frame labels/plugs exist in certificated installations
FD30, FD60, FD30S — decoding the ratings
| Marking | Meaning | Typical locations |
|---|---|---|
| FD30 | 30 minutes fire resistance | Flat entrance doors, most internal fire doors, HMO room doors |
| FD60 | 60 minutes | Plant rooms, between commercial units, protected shafts, higher-risk separation |
| FD30S / FD60S | Rating + cold smoke control (seals) | Flat entrances, escape corridors and stair doors — wherever smoke matters |
| FD90 / FD120 | 90 / 120 minutes | Special separation: archives, transformer rooms, compartment walls of high rating |
The door has no marking — now what?
Unmarked doors are the daily reality in older buildings. An experienced inspector weighs construction (thickness, mass, edge details, glazing type, frame), age and position to judge whether the door is a plausible nominal fire door, a non-fire door in a fire position, or certified stock with lost identity. The honest outcome is risk-based: nominal doors in lower-risk positions may be upgraded (seals, closers, glazing) and managed; doors protecting sleeping risk or single stairs with no provable performance typically end up on the replacement schedule, because nobody can certify 30 minutes into a door after the fact.
Frequently Asked Questions
Are all heavy doors fire doors?
What do the coloured plugs mean?
Is a fire door still a fire door with the closer removed?
Do internal doors in ordinary houses need to be fire doors?
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