What makes a fire door different from an ordinary door?
Fire doors have denser cores, hardwood or steel edges, and frames fitted with intumescent seals that swell in heat to close the gap around the leaf. Hinges, locks and closers are chosen and positioned to match the test. An ordinary internal door can fail in a few minutes; a 30-minute fire door is designed to hold for at least half an hour.
How does a fire door stop smoke?
Smoke spreads faster than flames and causes most fire deaths. Smoke control doors (the S in FD30S) add brush or blade seals that restrict cold smoke before the intumescent strips activate. They still rely on tight, even gaps.
Why is the doorset, not the door, certified?
Fire tests are carried out on complete assemblies. Certification then covers that assembly within a defined field of application. A certified leaf hung in an untested frame with random hardware has no evidence behind it — which is why we supply complete doorsets.
Why does installation matter so much?
Most failures found in fire door surveys come from fitting: oversized gaps, frames not sealed to the wall, missing hinge screws or closers that don't latch. BS 8214:2026 sets out good practice for installation and maintenance across timber, steel and composite doors.
Common questions
How long does a fire door last in a fire?
As long as its rating — 30, 60, 90 or 120 minutes — provided it is closed, undamaged and fitted as tested.
Does a fire door have to be kept shut?
Yes, unless it is held open by an approved device that releases it on alarm.
Doorsets mentioned in this guide
FD30 Fire Doorsets
30-minute certified doorsets — the workhorse of flats, offices and HMOs.
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FD30S Smoke Control Doorsets
30-minute doorsets with tested smoke seals for flats, corridors and stairs.
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Fire Door Supply & Fit
Survey, certified doorset, installation and handover — one fixed quote.
View doorsetsMore guides
- How to check a fire door is certified
- How much does a fire door cost to supply and fit in 2026?
- BS 8214:2026: what the new fire door code of practice changes
- Which fire door signs do you need?
- Glass in fire doors: what's allowed?
- Repair or replace: can a fire door be fixed?
- Who is responsible for flat front fire doors?
- Fire door ratings explained: FD, E, EI and S