The 10 Most Common
Fire Door Failures
Real inspection data from 500+ FDIS-certified surveys across London and the South East — the defects found most often, why each compromises fire safety, and exactly what remediation is required.
Defect Frequency — What We Find
Every percentage below is drawn from FDIS-certified inspections carried out across HMOs, residential blocks and converted properties in London and the South East between 2023 and 2024. The data is consistent with national industry findings.
Why 68% have defects: Most defects are not visible during a routine landlord walk-through. Painted-over seals, marginally excessive gaps, hinges of incorrect specification, and obscured certification marks all appear normal to the untrained eye. A competent inspection is not a visual check — it is a component-by-component assessment against the door's specification.
The single most common and most dangerous fire door defect. A fire door that does not self-close and latch from any open position provides zero fire protection — it is indistinguishable from a standard door in a fire scenario. Closers fail through spring fatigue, arm disconnection, incorrect adjustment, wrong specification for the door weight, or deliberate disabling by occupants who find them inconvenient.
Causes
Spring fatigue or mechanical failure over time; arm disconnected from mounting plate; closer body leaking hydraulic fluid; incorrect spring power for door weight; tenant removal
Remediation
Closer adjustment where the mechanism is functional; replacement with a certified overhead closer (BS EN 1154 compliant) where beyond adjustment; new installation where absent
Intumescent seals are designed to expand rapidly under heat — typically activating at 150–200°C — to close the gap between the door leaf and frame, blocking fire from penetrating the assembly. Without functioning seals, even a certified and correctly installed door will allow fire through the gaps within minutes of a fire starting. The most commonly missed failure mode is seals that have been painted over during redecoration.
Causes
Painted over during redecoration (most common); dried out, shrunk or cracked with age; partially or fully removed; installed in the wrong position or with gaps in continuity
Remediation
Full seal replacement — painted seals cannot be stripped and reused as this risks damaging the groove. New certified intumescent (and cold smoke if FD30S/FD60S) seals fitted to the full perimeter
The maximum permitted gaps around a fire door are tightly specified because fire gases exploit the path of least resistance. A gap 2mm over tolerance can allow fire and hot gases to penetrate in a scenario where a compliant door would not. Gaps typically develop through building settlement, door drop from worn or insufficient hinges, seasonal timber movement, or poor original installation.
Maximum Permitted Gaps
Head and both jambs (sides): 3mm maximum — the "coin test". Threshold (base): 4mm maximum with intumescent threshold seal. Between double leaves where fitted: 3mm maximum
Remediation
Hinge adjustment or replacement to lift a dropped door; door re-hanging; planing of the door edge in limited cases; full door replacement where structural drop has occurred
Every component of a fire door assembly must be certified and compatible with the door's test evidence. This includes hinges, locks, latches, handles, escutcheons, letter plates, door closers, and vision panel beading. Replacing any certified component with a non-certified equivalent — however similar it appears — technically invalidates the door's certified performance. This is frequently the result of routine maintenance using standard (non-fire-rated) hardware from a builder's merchant.
Most Common Causes
Routine maintenance using standard hardware; tenant modifications to flat entrance door; vision panel beading replaced with non-certified equivalent during glazing repair; non-certified letter plates (a specific high-risk item)
Remediation
Replacement of all non-certified components with certified equivalents compatible with the door's test evidence. All replacements referenced to the specific door's certification documentation
UK fire doors must carry a permanent certification mark — typically a coloured intumescent plug or manufacturer's certification insert — on the hinge edge of the door leaf. This mark should survive the life of the door. When it is absent, painted over, sanded off, or illegible, the door's certified performance cannot be confirmed from visual inspection alone and specialist assessment is required. Pre-1992 doors may pre-date mandatory certification marking entirely.
Causes
Painted over during redecoration; sanded off during door planing (gap adjustment); never present in older pre-1992 doors; obscured by additional hardware fitted by tenants or maintenance contractors
Remediation
Investigative probe to locate plug beneath paint where possible; if plug confirmed present, document and re-expose; if absent, specialist assessment of door core to determine likely certification status; replacement if cannot be confirmed
Physical damage to the door leaf or frame can compromise the structural integrity of the assembly and create paths for fire gases. Even minor holes — such as those left by redundant fixings, a removed letter plate, or old cable entry points — must be filled with certified fire-rated filler, not standard decorator's filler. Splits or cracks in the door leaf require assessment: surface scratches may be acceptable; damage penetrating the fire-rated core is not.
Common Types
Holes from removed hardware or fixings; splits from forced entry attempts; rot in timber frames (especially older stock); cracks from building movement; damage to door stop from impact
Remediation
Certified fire-rated filler for minor holes and surface damage; specialist assessment for structural splits or cracks; frame repair or replacement for rot; full door replacement where core integrity is compromised
Hinges are a structural component of the fire door assembly. Insufficient numbers, incorrect specification (using standard residential hinges instead of certified fire-rated hinges), or worn hinges that allow the door to drop can each affect performance. A dropped door creates excessive gaps — defect 03 above — and may prevent the self-closer from operating effectively. The minimum for FD30 doors is three certified fire-rated hinges of at least 100mm size.
Common Failures
Only two hinges fitted (non-compliant); standard residential hinges used instead of certified fire-rated; worn hinges causing door drop and excessive gaps; hinges of insufficient size for door weight
Remediation
Replacement of all hinges with a certified set of three (or more) fire-rated hinges of appropriate specification. Re-hanging the door to reset correct gap tolerances where door drop has occurred
Vision panels are among the most frequently modified components on a fire door and among the most frequently non-compliant. The glazing, the beading retaining it, and the installation method must all be certified and compatible with the door's test evidence. Standard float glass, even in a fire door frame, provides no fire resistance. Non-certified timber or PVC beading is a specific and common failure point.
Common Failures
Standard glass (not fire-rated) installed; non-certified beading used during previous repair; cracked glazing not replaced; vision panel added to a door not certified with a panel; panel size outside the tested specification
Remediation
Replacement with certified fire-rated glazing and certified beading compatible with the door's test evidence. Where a panel has been added to a non-panel door, full specialist assessment is required
A fire door that is permanently wedged or propped open provides no fire protection whatsoever. The frequency with which this is found on inspection — particularly in HMOs and student accommodation — reflects how often occupants prioritise convenience over safety. The only legally compliant method of holding a fire door open is an electromagnetic hold-open device linked to the building's fire alarm system.
Why It Happens
Tenants find self-closers inconvenient for daily movement between rooms; communal doors propped open for ventilation; door closer is too heavy for the door's regular use pattern
Remediation
Remove wedge or prop immediately; consider electromagnetic hold-open device (linked to fire alarm) for doors where the use pattern makes closure genuinely impractical; resident information and tenancy agreement clauses
The threshold — the base of the door — is the most difficult gap to control and is governed by a 4mm maximum tolerance. A certified intumescent threshold seal is often required and is frequently missing, particularly on older fire doors and on doors where the original threshold seal has never been replaced. This defect is often found in combination with excessive gap tolerances (defect 03).
Causes
Never installed on older doors; worn or compressed beyond function; damaged by heavy foot traffic; removed during flooring works and not reinstated; wrong product specified for the gap width
Remediation
Supply and fit of a new certified intumescent threshold seal of the correct specification for the gap width. Where gap exceeds 4mm, re-hanging or gap adjustment work required before or alongside seal installation
Defect Severity — When to Act
In fire safety law, defects must be remediated as soon as reasonably practicable. For critical defects this means same-day action. Here is the framework we apply — and that we recommend all responsible persons follow.
| Severity | Examples from This List | Required Timescale | Documented Action |
|---|---|---|---|
| ⚠ Critical | Defect 01 (no closer), Defect 03 (door not latching), Defect 09 (propped open), missing seals entirely | Same day — or take door out of service until remediated | Immediate notification by phone · Written report same day · Remediation date confirmed |
| Significant | Defects 02–08, 10 where not immediately life-safety critical | Within 28 days as a guide — sooner if fire risk assessment specifies | Full written report · Prioritised remediation schedule · Follow-up sign-off inspection |
| Advisory | Minor surface damage, seal approaching end of life, borderline gap at advisory threshold | Document and monitor — action at next scheduled inspection | Flagged in inspection report · Noted for next scheduled visit · No immediate action required |
Frequently Asked Questions
What is the most common fire door defect?
The most common defect found on inspection is a defective or missing self-closing device — present in 41% of all doors inspected across older residential stock. A fire door without a functioning self-closer provides zero fire protection regardless of its rated performance. It is also one of the most dangerous defects because it is so easily overlooked on a routine landlord walk-through — the door still looks intact and may even close if pushed.
Why are painted-over seals so common?
Intumescent seals sit in a groove around the door leaf edge, typically flush with the surface. When a door is redecorated, it is very easy to paint over the seal without realising its significance. This is especially common in properties where decorating has been carried out by general contractors rather than fire door specialists. A seal covered in two or three coats of paint may be completely unable to expand and activate when needed. It must be replaced — not stripped — because the removal process risks damaging the groove.
Can a landlord carry out their own fire door checks?
A landlord can carry out interim visual checks between formal inspections — checking that the door closes and latches, that the self-closer operates, and that there is no obvious damage. However, these interim checks do not substitute for a competent, component-by-component FDIS-certified inspection. 68% of defects found on inspection are not visible during a routine walk-through. The statutory inspection requirement under the 2022 Regulations requires a competent person to carry out the check — which means someone with the knowledge to assess all components against specification.
What happens if a fire door is found to be wedged open during an inspection?
A wedged-open fire door is a Critical defect requiring immediate action. Our inspectors remove any props or wedges found during inspection and inform the responsible person immediately. We also document the finding with photographs. Where the use pattern of the door makes it impractical to keep closed, an electromagnetic hold-open device linked to the building's fire alarm system — which releases and closes the door automatically on alarm activation — is the only compliant solution.
What is the difference between an intumescent seal and a smoke seal?
An intumescent seal activates under heat — expanding to fill the gap between the door and frame and block fire. A smoke seal (also called a cold smoke seal) is a flexible brush or wiper seal that physically blocks cold smoke from passing through the gap at ambient temperatures — before the fire is hot enough to activate the intumescent seal. The S suffix in FD30S and FD60S specifically means a cold smoke seal is fitted. Doors rated FD30 without S have intumescent seals but no cold smoke seal. In occupied residential buildings, the S rating is almost always required.
My fire doors passed a previous inspection — do they need checking again?
Yes. Fire door compliance is not a one-time event — it is an ongoing obligation. Self-closers deteriorate, seals age and crack, gaps develop as buildings settle, and tenants can damage or modify doors between inspections. A door that passed 12 months ago may have a disconnected closer today. The statutory quarterly and annual inspection frequencies reflect this reality: regular inspection is required because compliance can deteriorate between visits.
Find Out Which Defects Your Doors Have — Book an Inspection
When component repair is enough and when a full certified door set is required.
What each repair costs: seals 50-90, closers 90-160, hinge sets 80-160, full replacement 400-750.
See exactly which defects were found across 8 HMO doors and what remediation each required.
Legal framework, inspection frequencies and the full 6-step inspection process explained.