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Kitchen extraction cleaning - fire investigation
When a commercial kitchen fire is investigated, the findings are often depressingly familiar: grease-laden ductwork that helped the fire spread, and neglected maintenance behind it. The extraction is a recurring theme in kitchen fire investigations. Here is what such investigations usually reveal, and the lesson for keeping your extraction clean. This is general information on fire, not fire-investigation advice.
The short answer
After a serious commercial kitchen fire, it's usually investigated - to establish how it started, how it spread, and why. And the findings, across many such fires, form a recurring pattern - one in which the extraction system features prominently. Here's what kitchen fire investigations usually reveal, and what to learn from it. This is general information on fire, not fire-investigation advice; investigation is a specialist matter. The recurring role of the ductwork. A very common finding in kitchen fire investigations is that grease-laden ductwork helped the fire spread. The pattern: a fire starts (a flare-up, a fryer, equipment), is drawn into the extraction, reaches grease-laden ductwork, ignites the grease, and travels along the ducts - spreading through the hidden ductwork into the roof void and other parts of the building. So a fire that might have stayed contained at the cooking line instead becomes a serious building fire, carried and fed by the greasy ducts. Investigation after investigation finds this: the extraction ductwork as the route by which a kitchen fire spread and escalated. Neglect behind it. Behind the grease-laden ductwork, investigations often reveal neglected maintenance: an extraction that hadn't been cleaned to standard, or often enough, or in some cases at all - letting the grease build up over time to the point where it could fuel and spread a fire. So the physical finding (greasy ducts) usually reflects an underlying failing (neglected cleaning). The grease didn't appear overnight; it accumulated through inadequate maintenance. Other recurring findings. Alongside these, investigations commonly find: Seized fire dampers - fire dampers grease-jammed and unable to close, so they failed to contain the fire's spread through the ductwork (the containment that should have limited the fire didn't work). Missing or inadequate access - too few access panels, so the ductwork couldn't be (or wasn't) properly cleaned, contributing to the grease build-up. Under-managed fire risk - a general pattern of the extraction fire risk not being taken seriously or managed (no proper cleaning regime, no records, no attention to the ducts). So the findings cluster around a neglected, grease-laden, poorly-maintained extraction. The recurring lesson. So the recurring lesson from kitchen fire investigations is clear: grease build-up in a neglected extraction is a major factor in how kitchen fires spread and become serious. The extraction, when neglected, is repeatedly found to be what turned a manageable fire into a catastrophe. This is exactly the risk that regular extraction cleaning addresses. The positive flip side. The flip side is the positive lesson: a clean, well-maintained extraction removes what investigations so often find. A clean duct (no grease fuel), that's cleanable (good access), with working fire dampers (containing spread), denies a fire the fuel and the path it needs to spread through the ductwork - making a fire far more likely to stay contained. So the recurring investigation findings are, in effect, a repeated demonstration of why extraction cleaning matters. The takeaway. So a kitchen fire investigation usually reveals grease-laden ductwork that spread the fire, and neglected maintenance behind it - a recurring pattern in which the extraction is central. The lesson is to keep your extraction cleaned to standard and well-maintained (cleanable, with working dampers), so your system isn't the one an investigation would find. So learn from the recurring findings, and keep the ductwork clean. This is general information on fire, not fire-investigation advice.
Key points
A recurring pattern
When a serious commercial kitchen fire is investigated, a very common finding is that grease-laden ductwork helped the fire spread. The recurring pattern: a fire starts (a flare-up, a fryer, overheating equipment), is drawn into the extraction, reaches grease-laden ductwork, ignites the grease, and travels along the ducts - spreading through the hidden ductwork into the roof void and other parts of the building. So a fire that might have stayed contained at the cooking line instead becomes a serious building fire, carried and fed by the greasy ducts.
Investigation after investigation finds this: the extraction ductwork as the route by which a kitchen fire spread and escalated. It's a depressingly familiar theme - the grease in the ducts providing the fuel, and the ductwork providing the path, that turned a small fire into a large one. So the ductwork is a recurring central finding in kitchen fire investigations, not an occasional one. This tells you something important: the extraction ductwork is repeatedly implicated in how kitchen fires become serious. Why the ductwork is so often greasy - the neglect behind it - is covered next. So a recurring pattern - the ductwork spread the fire - is the headline finding: greasy ducts as the route of spread. So investigations repeatedly find the ductwork carried the fire. This is general information on fire, not fire-investigation advice.
Neglect behind it
Behind the grease-laden ductwork, investigations often reveal neglected maintenance: an extraction that hadn't been cleaned to standard, or often enough, or in some cases at all - letting the grease build up over time to the point where it could fuel and spread a fire. So the physical finding (greasy ducts) usually reflects an underlying failing (neglected cleaning). The grease didn't appear overnight; it accumulated through inadequate maintenance over months or years.
This is the deeper finding: the fire spread through greasy ducts, and the ducts were greasy because the extraction wasn't properly maintained. So the neglect of the extraction cleaning is, in effect, a root factor in how the fire spread - the missing maintenance allowed the grease build-up that fuelled and carried the fire. Investigations frequently find no proper cleaning regime, long gaps since the last clean (or no record of any), and a system left to accumulate grease. So neglect behind it - an extraction that wasn't maintained - is the recurring underlying finding: the grease-laden ducts that spread the fire trace back to neglected cleaning. This is what makes the finding a lesson rather than just an observation: the neglect (and thus the spread) was preventable by proper cleaning. So the greasy ducts reflect neglected maintenance behind them. This is general information on fire, not fire-investigation advice.
Other common findings
Alongside the grease-laden ducts and neglect, kitchen fire investigations commonly find several related things. Seized fire dampers: fire dampers grease-jammed and unable to close, so they failed to contain the fire's spread through the ductwork - the containment that should have limited the fire didn't work (as covered in the stuck-fire-damper page). Missing or inadequate access: too few access panels, so the ductwork couldn't be (or wasn't) properly cleaned, contributing to the grease build-up that fuelled the fire.
And a general pattern of under-managed fire risk: the extraction fire risk not being taken seriously or managed - no proper cleaning regime, no records, no attention to the ducts, the risk effectively ignored until the fire. So the findings cluster around a neglected, grease-laden, poorly-maintained extraction system, with multiple related failings (dirty ducts, seized dampers, poor access, no regime). These reinforce each other: poor access allows grease build-up, grease seizes the dampers and fuels the fire, and the lack of a maintenance regime lets it all happen. So other common findings - seized dampers, poor access, under-managed risk - fill out the recurring picture: it's not just grease, but a whole neglected extraction. So investigations find a cluster of extraction failings, not one. This is general information on fire, not fire-investigation advice.
The recurring lesson
So the recurring lesson from kitchen fire investigations is clear: grease build-up in a neglected extraction is a major factor in how kitchen fires spread and become serious. The extraction, when neglected, is repeatedly found to be what turned a manageable fire into a catastrophe - the grease fuelling the fire, the ducts carrying it, the seized dampers failing to contain it, all tracing back to inadequate maintenance.
This is exactly the risk that regular extraction cleaning addresses. The investigations are, in a sense, a repeated real-world demonstration of the fire-safety case for cleaning: they show, again and again, what happens when the extraction is neglected - the grease-laden ducts spread the fire. So the findings aren't just about individual fires; they're a pattern that carries a lesson for every kitchen operator: a neglected extraction is a fire-spread risk, proven repeatedly. So the recurring lesson - neglected extraction spreads fires - is the message to take from the investigations: keep your extraction cleaned and maintained, because the alternative is exactly what these investigations keep finding. The positive flip side of this lesson is covered next. So the investigations repeatedly prove neglect spreads fires. This is general information on fire, not fire-investigation advice.
Be the exception
The flip side is the positive, actionable lesson: a clean, well-maintained extraction removes what investigations so often find. A clean duct (no grease fuel), that's cleanable (good access), with working fire dampers (containing spread), denies a fire the fuel and the path it needs to spread through the ductwork - so a fire is far more likely to stay contained. So keeping your extraction clean and maintained means your system isn't the one an investigation would find at fault.
So the practical takeaway is to be the exception to the recurring findings: keep the extraction cleaned to the TR19 Grease standard at a risk-based frequency (so no grease build-up to fuel a fire), ensure good access so the whole system can be cleaned (fitting panels where needed), keep the fire dampers maintained and tested (so they work - a fire-safety matter alongside the cleaning), and manage the extraction fire risk properly (a cleaning regime, records, attention to the ducts). Do this, and if a fire ever occurs, your extraction won't be the grease-laden, neglected system that spreads it - it'll be the clean, maintained one that helps contain it. So be the exception - a clean system removes the findings - is the constructive conclusion: learn from the recurring investigation findings and make your extraction the opposite of what they reveal. So keep your extraction clean and maintained, and don't be the next finding. This is general information on fire, not fire-investigation advice.
Questions
Often the same things: grease-laden ductwork that helped the fire spread, and neglected maintenance behind it - plus seized fire dampers, poor access, and an under-managed extraction fire risk. Kitchen fire investigations often reveal a recurring pattern centred on the extraction. The most common finding is grease-laden ductwork that helped the fire spread - the grease fuelling the fire and the ducts carrying it through the building, turning a contained fire into a serious one. Behind that, they often find neglected maintenance: an extraction not cleaned to standard, or often enough, or at all, letting the grease build up. Other recurring findings include seized fire dampers (grease-jammed, so they failed to contain the spread), missing or inadequate access (so the ductwork couldn't be properly cleaned), and a general pattern of the extraction fire risk being under-managed (no regime, no records). So the findings cluster around a neglected, grease-laden, poorly-maintained extraction. The recurring lesson is that a neglected extraction is a major factor in how kitchen fires spread. So grease-laden ducts and neglect, repeatedly. So neglected, greasy extraction systems. This is general information on fire, not fire-investigation advice.
Because grease in a neglected extraction is a leading way kitchen fires spread - the grease fuels the fire and the ducts carry it through the building - so a neglected, greasy extraction is repeatedly implicated in how fires escalate. The extraction is a common finding in kitchen fire investigations because grease build-up in a neglected extraction is a leading mechanism by which kitchen fires spread and become serious. When a fire starts, it can be drawn into the extraction; if the ductwork is greasy, the grease is fuel, so the fire ignites it and travels along the ducts, spreading through the building. So a neglected, grease-laden extraction repeatedly turns out to be the route by which a fire escalated from a contained flare-up to a building fire. Because grease build-up is common in neglected systems (and neglect is common), this pattern recurs across many fires. So the extraction features prominently because it's genuinely a major factor in fire spread - not a coincidence, but a real mechanism. This is exactly why regular extraction cleaning matters for fire safety. So because greasy ducts are a leading way fires spread. So because a neglected duct spreads fires. This is general information on fire, not fire-investigation advice.
Often - seized fire dampers (frequently grease-jammed) that failed to close and contain the fire's spread through the ductwork are a common finding, so the containment that should have limited the fire didn't work. Yes - seized fire dampers are a common finding in kitchen fire investigations. Fire dampers are meant to close in a fire to seal the ductwork where it passes through fire-rated walls or floors, containing the fire's spread through the ducts. But investigations frequently find dampers that were seized - often grease-jammed from the same grease build-up that fuelled the fire, or from corrosion and neglect - and so failed to close when needed. So the containment that should have limited the fire's spread through the ductwork didn't work, letting the fire travel as if the dampers weren't there. This compounds the grease problem: the greasy ducts spread the fire, and the seized dampers failed to stop it. It's part of the recurring picture of a neglected extraction (dirty ducts, seized dampers, poor access). So keeping fire dampers maintained and tested (a fire-safety matter) matters alongside keeping the ducts clean. So yes - seized dampers that failed to contain the fire are common. So often; grease-seized dampers that didn't close. This is general information on fire, not fire-investigation advice.
That a neglected, grease-laden extraction is a major factor in how kitchen fires spread - so keeping the extraction cleaned and maintained (no grease fuel, cleanable, with working dampers) removes what investigations keep finding. The lesson from the recurring findings is that grease build-up in a neglected extraction is a major factor in how kitchen fires spread and become serious - proven repeatedly across investigations. The extraction, when neglected, is what keeps turning manageable fires into catastrophes. So the actionable lesson is to make your extraction the opposite of what investigations find: keep it cleaned to the TR19 Grease standard at a risk-based frequency (no grease to fuel a fire), ensure good access so the whole system can be cleaned, keep the fire dampers maintained and tested (so they contain any spread), and manage the extraction fire risk properly (a regime and records). A clean, well-maintained extraction removes the fuel and the path a fire would use - so if a fire occurs, your system helps contain it rather than spread it. So the lesson is to keep the extraction clean and maintained, unlike the neglected systems investigations find. So keep it cleaned and maintained. So learn from them - clean and maintain your extraction. This is general information on fire, not fire-investigation advice.
If it's grease-laden, overdue a clean, poorly accessible, or has untested dampers, it could be; if it's cleaned to standard, cleanable and well-maintained, it wouldn't be at fault - so keeping it clean and maintained is how to avoid being the finding. Whether your extraction would be a problematic finding in a fire investigation depends on its state. If it's grease-laden, overdue a clean (or never properly cleaned), poorly accessible (so it can't be cleaned), or has seized or untested fire dampers, then it's exactly the kind of neglected system investigations repeatedly find at fault in fire spread - so it could be a finding. If, on the other hand, it's cleaned to the TR19 Grease standard at the right frequency, cleanable (good access), and well-maintained (with working, tested fire dampers), then it wouldn't be at fault - it would be the clean, well-managed system that helps contain a fire. So the way to ensure your extraction wouldn't be an adverse finding is to keep it cleaned and maintained: no grease build-up, good access, working dampers, a proper regime with records. So assess your own system honestly against what investigations find, and keep it clean and maintained. So it depends on its state - keep it clean to avoid being a finding. So only if it's neglected; keep it maintained. This is general information on fire, not fire-investigation advice.
No - fire investigation is a specialist matter carried out by fire investigators and authorities after a serious fire, not something you arrange; your role is prevention - keeping the extraction cleaned and maintained so your system isn't a factor. No - fire investigation isn't something you arrange. After a serious fire, investigation is carried out by specialists (fire investigators, the fire and rescue service, insurers' investigators, and others as appropriate) to establish how the fire started and spread - it's a specialist, professional matter, and this page is general information, not fire-investigation advice. Your role isn't to investigate but to prevent: to keep your extraction in a state that wouldn't be a factor in a fire's spread. That means keeping the ductwork cleaned to the TR19 Grease standard at the right frequency (no grease fuel), ensuring good access (so it can be cleaned), keeping the fire dampers maintained and tested (a fire-safety matter), and managing the extraction fire risk properly. So learn from what investigations reveal (grease-laden, neglected extraction spreads fires), and act on the prevention side - keeping your system clean and maintained - so investigation of your premises would never find your extraction at fault. So no - your job is prevention, not investigation. So no; focus on keeping the extraction clean. This is general information on fire, not fire-investigation advice.
Fire investigations repeatedly find grease-laden, neglected ductwork; we clean the whole system to TR19 Grease and keep it cleanable and maintained - so your extraction is the clean, well-managed system that helps contain a fire, not the one that spreads it. Ask us to keep your extraction out of the findings. This is general information on fire, not fire-investigation advice.
