The six faults we find most
- Gaps that are too wide round the door, so smoke and flame get through.
- Missing, damaged or painted seals, so the gaps cannot seal in a fire.
- Closers that do not shut the door, leaving it open in a fire.
- Damaged frames and loose hinges, so the door drops or pulls away.
- Gaps behind the frame with no fire stopping.
- Doors wedged open, which cancels the whole fire door.
Common Fire Door Defects at a Glance
A fire door is a set of parts tested together: the leaf, frame, hinges, seals, closer, glass and hardware. If one part fails, the whole door can fail. That is why inspectors check every part, every time.
Below, each defect has a quick check you can do yourself. Self-checks are a good habit between inspections, but they do not replace a full inspection by a trained person.
Fire Door Gaps That Are Too Wide
What it looks like
You can see light round the edge of the closed door, or the gap is wider at the top than the bottom. Most fire doors are tested with gaps of about 2 to 4 mm at the top and sides. The gap under the door depends on the door’s test evidence and whether it has a bottom seal.
Why it matters
Smoke and hot gas find the easiest way through. A gap of just a few extra millimetres lets smoke reach the escape route long before the door itself burns.
Quick check
Close the door. Look round the edges. A £1 coin is about 3 mm thick: if it slides in easily with room to spare, the gap may be too wide. Common causes are sagging hinges, a shrunken door or a door cut down for new flooring.
Usual fix
Re-hanging the door and resetting the hinges costs around £80–£180. Wider gaps may need a hardwood edge strip at £150–£300, and a large bottom gap may need a drop seal at £120–£250.
Missing or Painted Fire Door Seals
What it looks like
The strip in the edge of the door or frame is missing, torn, loose or covered in paint. Brush or fin smoke seals may be flattened or ripped out.
Why it matters
An intumescent strip swells in the heat of a fire and seals the gap. A smoke seal stops cold smoke early on, before the strip reacts. Paint stops a strip swelling properly, and a missing seal leaves an open path for smoke.
Quick check
Open the door and look along the edges of the leaf or frame. Each side and the top should have a continuous strip, clean and unpainted. Doors marked FD30S or FD60S should also have a smoke seal.
Usual fix
Renewing the intumescent and smoke seals costs around £60–£140 per door. The new seals must match the door’s test evidence.
Fire Door Closers That Do Not Close
What it looks like
The door stops a few centimetres short of the frame, or closes but does not latch. In shared houses, the closer arm is often disconnected or removed completely.
Why it matters
A fire door only protects anyone when it is shut. People rarely close doors behind them when escaping a fire, so the closer has to do it.
Quick check
Open the door fully and let go. It should close and latch on its own. Try again from half open. If it stops, slams hard or needs a push, it needs attention.
Usual fix
Often the closer just needs adjusting, or the latch or strike plate needs lining up. A new overhead closer costs around £120–£250. Busy doors need a heavy-duty closer to last.
Damaged Fire Door Frames and Loose Hinges
What it looks like
The frame is split, cracked or moves when you push it. Hinge screws are loose or missing, or one of the three hinges has been swapped for an ordinary one.
Why it matters
A sound door in a weak frame still fails. A loose frame can pull away in a fire, and worn hinges let the door drop, which opens the gaps and stops it latching.
Quick check
Push the frame gently on each side. Lift the door by its handle: it should not move up and down. Check every hinge screw is in place and tight.
Usual fix
Three new fire-rated hinges cost around £90–£180. A badly split frame usually means a new doorset, from £550–£950 supplied and fitted.
Fire Stopping Gaps Around Fire Doors
What it looks like
The gap between the frame and the wall is open, packed with ordinary foam or hidden behind the architrave. New cables or pipes may have been run through the wall above the door, leaving holes.
Why it matters
Fire does not need to go through the door if it can go round it. An open gap behind the frame lets smoke and flame bypass the whole fire door.
Quick check
This one is hard to see without removing the architrave. Look for gaps where the frame meets the wall, and for new holes around the door. A trained inspector will check it properly.
Usual fix
The gap is filled with a fire-rated sealant or mastic that suits the door’s test evidence. Ordinary expanding foam is not a fire stop unless it is tested for that use.
Fire Doors Wedged or Held Open
What it looks like
A wedge, chair, fire extinguisher or hook keeps the door open. Scuffs on the floor or a hook on the wall are signs it happens often.
Why it matters
A wedged fire door is no better than an open doorway. It is one of the most common reasons fire spreads through a building.
Quick check
Walk the building at different times of day. Ask why each wedged door is wedged, as the reason points to the fix.
Usual fix
If the door needs to stay open, fit a hold-open device linked to the fire alarm, so it closes when the alarm sounds. If the door is too heavy, adjust the closer or fit a free-swing closer. Testing a hold-open with the alarm costs around £15–£35 per device.
Other Fire Door Defects to Watch For
Ordinary glass
Glass panels must be fire rated and held with the right beads and seals. Ordinary glass shatters early in a fire.
Missing signs
Most fire doors need a “Fire door keep shut” sign. Signs cost around £10–£25 per door.
Unrated hardware
Letter plates, spyholes, locks and handles must be fire rated and allowed by the door maker.
Holes and damage
Old lock holes, bolt holes and kicked panels weaken the door. Small holes can be repaired from £80–£200.
No label or proof
Without a label, plug or paperwork, nobody can show the door is a fire door. It may need certifying or replacing.
Ordinary doors
Sometimes a fire door has been swapped for an ordinary one. It may look the same, but it will not hold back fire.
A Five-Minute Fire Door Defect Check
Use this simple routine between inspections. Note anything that fails and get it looked at.
- 1
Look for a label
Check the top or hinge edge for a label or plug that shows the door’s rating.
- 2
Check the gaps
Close the door and look for even gaps of about 3 mm, with no light showing.
- 3
Check the seals
Look for a continuous, unpainted strip on the sides and top.
- 4
Check the hinges
Three hinges, every screw in place, no movement when you lift the door.
- 5
Check it closes
Open the door fully, let go, and make sure it closes and latches on its own.
When a Fire Door Defect Means Replacement
Most defects can be repaired. Replacement is usually needed when the core of the door is damaged or the door cannot be proven to be a fire door.
| Defect | Usually repair | Usually replace |
|---|---|---|
| Gaps | Re-hang, edge strip or drop seal | Door shrunk or cut down too far |
| Seals | New seals to match the door | — |
| Closer | Adjust or replace the closer | — |
| Frame | Re-fix loose fixings | Split or badly damaged frame |
| Holes and damage | Small holes filled with a rated product | Many holes, split leaf or kicked-in panel |
| No label | Trace and certify the door if possible | Door cannot be proven, or is not a fire door |
Fire Door Defect Questions
What is the most common fire door defect?
Gaps that are too wide and closers that do not shut the door are the two we find most. In shared houses, closers removed by tenants and holes from extra locks are also very common. All of these are usually quick to fix.
What gap is allowed around a fire door?
Most fire doors are tested with gaps of about 2 to 4 mm at the top and sides. The gap under the door depends on the door’s test evidence and whether it has a bottom seal. Always check the maker’s instructions for your door.
Can I paint a fire door?
Yes, but never paint over the seals or the label. Painted intumescent strips may not swell properly in a fire, and painted smoke seals cannot seal the gap. If seals have been painted, they should be replaced.
Is it illegal to wedge a fire door open?
Wedging a fire door open can be a breach of fire safety law, as it stops the door doing its job. In workplaces and shared buildings, the responsible person can face action. Use a hold-open device linked to the fire alarm if a door must stay open.
Can a damaged fire door be repaired?
Often, yes. Gaps, seals, closers, hinges and small holes can all be repaired with fire-rated parts. If the core is damaged, the door is split or it cannot be proven to be a fire door, replacement is usually safer.
How do I know if a door is a fire door?
Look for a label or plug on the top or hinge edge. Fire doors are also heavier than normal doors and usually have intumescent seals. If there is no label and no paperwork, ask a trained inspector to check it.
Who should check fire doors for defects?
Anyone can do a quick visual check between inspections. A full inspection should be done by a trained, competent person who knows what each door’s test evidence allows. They will record each defect with photos and a fix.
How often should fire doors be checked for defects?
Many buildings check every six months, with busy doors checked more often. Blocks of flats over 11 metres need shared fire doors checked every three months and flat front doors every year. Your fire risk assessment may set its own interval.