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Kitchen extraction cleaning - fan types
An extract fan can sit on the roof (a roof fan) or within the duct run (an in-line fan) - and the two differ for cleaning, mainly in how they're accessed. A roof fan means working at height; an in-line fan sits in the ductwork and needs access panels to reach. Either way, the fan must be reached and cleaned. Here is how the two compare for cleaning and access. This is general guidance.
The short answer
Not every extract fan is on the roof. Kitchen extraction systems use fans in different positions, and the two main types - roof-mounted and in-line - differ for cleaning, mainly in how they're accessed. Knowing which you have, and how it's reached, helps make sure the fan actually gets cleaned. Here's how they compare. This is general guidance. The two positions. A kitchen extract fan sits in one of two main places. A roof fan is mounted on the roof, at the discharge (far) end of the system, drawing the air up and out. An in-line fan sits within the duct run - in the ductwork itself, somewhere along the run (often in a roof void, ceiling space, plant room or along an internal duct), rather than at the roof discharge. Both do the same job (drawing the air through the system), and both collect grease (all the grease-laden air passes through them) - so both must be cleaned. What differs is how you reach them. Reaching a roof fan. A roof fan is reached by getting onto the roof and working at height. So cleaning it needs: safe roof access (a way onto and around the roof), working-at-height equipment and precautions, and a crew set up and competent for roof work (as covered in working at height on roof fans). The access itself is the main challenge - it's outdoors, at height, weather-affected, and needs the right provision and competence. This is a big part of why roof fans are the most-neglected part of the system (out of sight, hard to reach). But it's very doable with the right contractor. Reaching an in-line fan. An in-line fan is reached through the ductwork - it sits in the duct run, so cleaning it needs access to the fan within the duct: access panels or hatches at the fan (openings in the ductwork to reach the fan and the duct around it - which is why adequate access panels matter, as covered in the access pages), and access to wherever the fan is located (a roof void, ceiling space or plant room - which may itself be awkward to get into). So the challenge here is duct access (getting into the duct at the fan) and internal location access, rather than height. The common thread. So both fan types collect grease and both must be reached and cleaned to standard - the difference is the access route, not whether cleaning is needed. Each has its own access challenge: a roof fan, the height and roof work; an in-line fan, the duct access panels and internal location. And each can be the part that gets skipped if the access is awkward and the contractor isn't set up for it (a roof fan skipped for the height; an in-line fan skipped or under-cleaned if it's hard to reach in the duct or lacks access panels). So the practical points: know which type you have and where the fan is; make sure there's adequate access to it (roof access for a roof fan; access panels and route for an in-line fan); and use a contractor equipped to reach and clean your fan type. Either way, a proper clean reaches the fan and cleans it, to the TR19 Grease standard. So both must be cleaned - they just differ in how you get to them. So know your fan type, ensure access, and make sure the clean reaches it. This is general guidance.
Key points
The two positions
A kitchen extract fan sits in one of two main positions. A roof fan is mounted on the roof, at the discharge (far) end of the system - drawing the air up through the ductwork and out through the roof. An in-line fan sits within the duct run - in the ductwork itself, somewhere along the run, often in a roof void, ceiling space, plant room or along an internal duct, rather than at the roof discharge. So the fan is either up on the roof, or tucked into the ductwork inside the building.
Both types do the same essential job: drawing the air (and everything in it - grease, heat, steam) through the whole system. And both collect grease, because all the grease-laden air passes through them - so grease builds up on the fan blades, housing and surrounds in either case. That means both types must be cleaned; neither is self-cleaning or grease-free. What differs between them is not whether they need cleaning (both do, equally) but how they're accessed to be cleaned - which is where the roof-vs-in-line distinction matters for the clean. So the two positions - on the roof, or in the duct run - set up the difference: same job, same grease, different access. The following sections cover how each is reached. So both collect grease; the difference is how you get to them. This is general guidance.
Reaching a roof fan
A roof fan is reached by getting onto the roof and working at height - so its access challenge is the height and the roof work. Cleaning a roof fan needs safe roof access (a way onto and around the roof - which varies hugely between buildings, from easy to difficult), working-at-height equipment and precautions (to work safely up there), and a crew competent and set up for roof work (as covered in working at height on roof fans). The work is outdoors, at height, affected by weather, and needs the right provision and competence to do safely.
This access challenge is a big part of why roof fans are the most-neglected part of the system: they're out of sight (up on the roof) and hard to reach (the height and access), so a contractor not set up for roof work may skip them. But with the right contractor - equipped and competent for working at height - reaching and cleaning a roof fan is entirely routine. So the key point for a roof fan is that its cleaning depends on safe roof access and working-at-height capability: make sure there's a way to access the roof, and use a contractor set up for the height. So reaching a roof fan - roof access and working at height - is its particular access requirement. Once reached, it's cleaned like any fan (grease removed from blades, housing and surrounds, condition checked). So a roof fan needs height access; ensure the clean provides it. This is general guidance.
Reaching an in-line fan
An in-line fan is reached through the ductwork - so its access challenge is getting into the duct at the fan, and getting to wherever the fan sits. Because the fan is within the duct run, cleaning it needs access to the fan inside the duct: access panels or hatches at the fan (openings in the ductwork that let the cleaners reach the fan and the duct around it - which is exactly why adequate access panels along the ductwork matter, as covered in the access pages). Without a panel at or near the fan, reaching it to clean it is difficult - so proper access provision is key.
And the in-line fan is located somewhere - often a roof void, ceiling space or plant room - which may itself be awkward to get into (a confined roof void, a high ceiling space). So reaching an in-line fan can involve both getting to its location and opening the duct via access panels to reach the fan. The challenge is duct and internal-space access rather than height. An in-line fan can be under-cleaned or skipped if it's hard to reach in the duct (poor access panels) or awkwardly located - just as a roof fan can be skipped for the height. So the key for an in-line fan is adequate access panels at the fan and a route to its location. So reaching an in-line fan - duct access panels and its location - is its particular requirement. Once reached, it too is cleaned like any fan. So an in-line fan needs duct access; ensure the panels and route exist. This is general guidance.
Both must be cleaned
The essential common thread is that both fan types collect grease and both must be reached and cleaned to standard - the difference is the access route, not whether cleaning is needed. Whether your extract fan is on the roof or in the duct run, it sees all the grease-laden air and builds up grease heavily - so it's a fire risk and a drag on performance if left uncleaned, and it must be included in a proper roof-to-canopy clean to the TR19 Grease standard. Neither type is exempt; neither should be skipped.
What differs is purely how the fan is accessed: height and roof work for a roof fan; duct access panels and internal location for an in-line fan. And each can be the part that gets skipped if its access is awkward and the contractor isn't set up for it - a roof fan skipped for the height, an in-line fan skipped or under-cleaned for poor duct access. So the risk is the same (the greasiest part left uncleaned); only the access reason differs. This is why knowing your fan type and ensuring proper access to it matters - so the clean can reach and clean it whichever it is. So both must be cleaned - same grease, different access - is the core point: don't let either type's access challenge become an excuse to leave the fan dirty. So whichever fan you have, make sure it's reached and cleaned. This is general guidance.
Know yours, ensure access
So the practical takeaway from the roof-vs-in-line distinction is about access: know which fan type you have and where it is, make sure there's adequate access to it, and use a contractor equipped to reach and clean it - so the fan actually gets cleaned, whichever type it is. Know yours: find out whether your extract fan is roof-mounted or in-line, and where it sits (the roof discharge, or a roof void / ceiling space / plant room) - so you know what access it needs.
Ensure access: for a roof fan, make sure there's safe roof access and use a contractor set up for working at height; for an in-line fan, make sure there are adequate access panels at the fan and a route to its location (and add access panels if they're lacking - poor access is a common reason fans get under-cleaned). Use the right contractor: one equipped and willing to reach your fan type (roof work, or duct access) and clean it properly. Then a proper clean reaches the fan and cleans it to the TR19 Grease standard, whichever type it is - and the greasiest part isn't left out for want of access. So know yours, ensure access - make sure the clean reaches the fan - is how the roof-vs-in-line difference translates into action: it's all about getting to the fan so it gets cleaned. So identify your fan, sort its access, and ensure it's cleaned. This is general guidance.
Questions
Both collect grease and both must be cleaned - the difference is access: a roof fan is reached by working at height on the roof, while an in-line fan sits in the duct run and is reached through access panels and its internal location. A kitchen extract fan sits either on the roof (a roof fan, at the discharge end) or within the duct run (an in-line fan, in the ductwork, often in a roof void or plant space). Both do the same job and both collect grease heavily (all the grease-laden air passes through), so both must be cleaned to standard. The difference is how they're accessed: a roof fan needs roof access and working at height (safe access onto the roof, height equipment and precautions, a crew set up for it); an in-line fan needs access to the fan within the duct (access panels/hatches at the fan) and access to wherever it's located (roof void, ceiling space, plant room). So the difference is the access route - height for a roof fan, duct panels and location for an in-line fan - not whether cleaning is needed. So both need cleaning; they differ in access. This is general guidance.
Yes - an in-line fan collects grease just as a roof fan does (all the grease-laden air passes through it), so it's equally a fire risk and drag on performance if left, and must be cleaned to standard as part of the whole-system clean. An in-line fan sits within the duct run rather than on the roof, but it does the same job (drawing the air through) and sees all the same grease-laden air - so grease builds up on its blades, housing and surrounds just as heavily as on a roof fan. That build-up is the same problem: a fire risk, and a drag on the fan's performance and life. So an in-line fan is not exempt from cleaning because it's not on the roof - it needs cleaning to the TR19 Grease standard as part of the whole-system clean, exactly like a roof fan. The only difference is how it's reached (through duct access panels and its internal location, rather than by working at height). So yes - it needs cleaning just as much; only the access differs. So yes; an in-line fan is cleaned too. This is general guidance.
Because they sit inside the duct run, so cleaners need openings in the ductwork at the fan to reach and clean it; without access panels at or near the fan, reaching it to clean it properly is difficult - which is why adequate access provision matters. An in-line fan is located within the ductwork, so unlike a roof fan (reached from outside on the roof), it's reached from inside the duct. Cleaning it therefore needs access panels or hatches at the fan - openings in the ductwork that let the cleaners reach the fan and the duct around it to clean them. Without a panel at or near the fan, the cleaners can't easily get to it, so it may be under-cleaned or skipped - the same neglect risk a roof fan faces from its height, but caused by poor duct access instead. This is why adequate access panels along the ductwork (and at the fan) matter for a cleanable system (as covered in the access pages). If an in-line fan lacks proper access, adding panels may be needed so it can be cleaned. So because they're reached through the duct, needing openings at the fan. So to reach the fan inside the duct. This is general guidance.
Neither is inherently harder - each has its own access challenge (a roof fan the height and roof work; an in-line fan the duct access and internal location), and either can be awkward; the key is a contractor set up for your fan's access, so it gets cleaned properly. Both fan types can be reached and cleaned properly with the right contractor - neither is inherently harder, they just present different access challenges. A roof fan's challenge is the height and roof work: safe roof access, working at height, weather - which needs a crew equipped and competent for it. An in-line fan's challenge is the duct and internal access: access panels at the fan, and getting to its location (a confined roof void, a high ceiling space). Which is more awkward depends on the specific building (an easy-access roof vs a hard one; a well-panelled duct in an accessible plant room vs a poorly-panelled fan in a tight void). Either can be the part that's skipped if its access is awkward and the contractor isn't set up for it. So the key isn't which is harder in general, but using a contractor equipped for your fan's particular access. So neither inherently - each has its own access challenge. So it depends on your setup; both are doable with the right crew. This is general guidance.
Ask your extraction cleaner or check the system - a roof fan is on the roof at the duct discharge, an in-line fan sits in the ductwork (often a roof void, ceiling space or plant room); knowing which, and where, tells you what access the clean needs. You can find out which fan type you have from your extraction cleaner or engineer (who'll identify it when they inspect or clean the system), from the system's documentation or installer, or by observation: a roof fan is visible on the roof at the point where the ductwork discharges; an in-line fan is within the duct run, so it's not on the roof but somewhere along the ductwork - commonly in a roof void, ceiling space or plant room. Knowing which type you have, and where it sits, tells you what access the cleaning needs (roof access for a roof fan; duct access panels and a route to its location for an in-line fan) - so you can make sure that access is provided and the fan gets cleaned. So ask your cleaner, or check where the fan is. So find out from your cleaner or by locating the fan. This is general guidance.
A well-equipped extraction specialist cleans both - working at height for a roof fan, through access panels for an in-line fan - but check they're set up for your fan's access, since a contractor not equipped for roof work may skip a roof fan. A capable extraction cleaning specialist is equipped to reach and clean both fan types: they'll have the provision and competence for working at height (for a roof fan) and for accessing fans within ductwork through access panels (for an in-line fan), cleaning either to the TR19 Grease standard as part of the whole-system clean. But it's worth checking, because the risk is a contractor not properly set up for your fan's access leaving it out - a roof fan skipped by a cleaner not equipped for working at height, or an in-line fan under-cleaned if the access is awkward and not tackled. So when choosing or booking a cleaner, confirm they'll reach and clean your fan type (roof work or duct access) and include the fan in the scope. A good specialist will. So yes, a well-equipped specialist does both - just confirm they're set up for yours. So yes; check they're equipped for your fan's access. This is general guidance.
Roof-mounted or in-line, your extract fan collects grease and must be cleaned. We're equipped to reach both - working at height for a roof fan, through access panels for an in-line fan - and clean the fan to TR19 Grease as part of the whole-system clean. Ask us to reach and clean your fan. This is general guidance.
