What is an FD30 fire door?
FD30 describes a fire door assembly rated to resist fire for thirty minutes; FD60 is the equivalent at sixty. The number is the tested period of fire resistance, not a guarantee of performance in any installation.
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<img src="https://fireoptix.co.uk/glossary/fd30/diagram.svg" alt="FD30 — diagram from FireOptix" width="880" height="620" loading="lazy">
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<a href="https://fireoptix.co.uk/glossary/fd30">What is an FD30 fire door?</a> — diagram by
<a href="https://fireoptix.co.uk">FireOptix</a>
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</figure>The rating comes from testing a complete assembly. In service, the same rating depends on the door being installed and maintained as tested — correct frame, correct hardware, correct gaps, seals intact.
Where a door also has to restrict smoke, that is a separate requirement from the fire resistance period and is usually indicated alongside it.
For an inspection, the practical questions are whether the assembly matches what was specified, whether it closes fully into the frame unaided, and whether anything about it has changed since it was fitted.
In practice
A register recording every door in a block as FD30.
The surveyor wrote it from the doors' appearance because no labels were visible and the building is of an age where the specification probably was that.
A designation on a register should record what is evidenced rather than what is likely, and 'rating not evidenced' is a legitimate and far more useful entry.
What the designation permits in terms of gaps and tolerances comes from the door's own certification, which is exactly what is missing here.
What goes wrong in practice
- Reading a label on the leaf as proof the installed assembly performs to that rating.
- Replacing hinges or closers during maintenance with unrated equivalents.