Roof fans vs in-line fans choosing for your layout

It depends on your building and layout - the roof and its access, the duct route, internal space, noise, and how the fan will be cleaned; neither is universally best, so it's a design decision for your premises. The choice between a roof-mounted and an in-line extract fan isn't a case of one being always better - the right option depends on your specific building and layout. Factors that weigh in: the building and roof (is there suitable, accessible roof space for a roof fan?); the duct route (how the ductwork runs to its discharge); internal/plant space (an in-line fan needs housing space inside; a roof fan needs roof space); noise (a roof fan puts it outside/above, an in-line fan within the building); and how the fan will be cleaned and maintained over its life (safe roof access for a roof fan; access panels and a reachable location for an in-line fan). So it's a considered design decision for your designer/installer, weighing these for your premises. So it depends on your layout - weigh the factors. So neither by default; it depends on your building. This is general commentary on system design.

Yes - a roof fan is cleaned by working at height on the roof, an in-line fan through access panels in the duct; the choice affects the access needed, so cleanability should be designed in whichever you pick. The fan position affects how the fan is accessed for its regular cleaning. A roof fan is cleaned by getting onto the roof and working at height, so it needs safe roof access - and if that access is difficult, the fan is more likely to be neglected. An in-line fan is cleaned through access panels in the ductwork at the fan, and needs its location (roof void, ceiling space, plant room) to be reachable - and if it's buried or poorly panelled, it too gets under-cleaned. So the choice affects the cleaning access, which is why cleanability should be part of the decision: whichever position you choose, design in the access (safe roof access, or good access panels and a reachable location) so the fan stays genuinely cleanable over its life. A fan that's hard to access is a fan that gets skipped. So yes - it affects the access, so design for cleanability. So yes; each needs its access designed in. This is general commentary on system design.

A roof fan keeps the fan and its noise outside the building, uses no internal space, and suits buildings with suitable accessible roof space; but it needs safe roof access for cleaning, so that access should be provided. A roof-mounted fan has several potential advantages, depending on the building. It sits outside, so it uses no internal plant or ceiling space (useful where internal space is tight). It keeps the fan noise outside and above the building (rather than within), which can suit the internal environment (though it may affect neighbours or be carried, depending on surroundings). And it suits buildings that have suitable, accessible roof space and where roof-mounting is practical. The main consideration to plan for is cleaning access: a roof fan is cleaned by working at height, so it needs safe roof access provided and a contractor set up for roof work - otherwise it risks being the neglected, greasy part. So a roof fan's advantages are external location, no internal space use, and noise kept outside - provided the roof access for cleaning is sorted. So it saves internal space and keeps noise out - if access is provided. So external siting and no internal space, with access planned. This is general commentary on system design.

An in-line fan sits within the building (no roof-mounting needed, useful where the roof is unsuitable), can suit certain duct routes, and is cleaned via access panels rather than at height; but it needs internal space and good access panels. An in-line fan has its own potential advantages, depending on the building. It sits within the ductwork inside the building, so it doesn't need roof-mounting - useful where the roof is unsuitable, inaccessible, shared or difficult. It can suit certain duct routes and layouts (sitting along the run rather than only at a roof discharge). And it's cleaned through access panels in the duct rather than by working at height on the roof (which can be more straightforward if the fan is well-located and panelled, and avoids roof access). The considerations to plan for are that it needs internal space to house it (a roof void, ceiling space or plant room), its noise is within the building (which may need attenuation), and it needs good access panels and a reachable location so it stays cleanable. So an in-line fan's advantages are no roof-mounting, route flexibility, and non-height access - given the internal space and good access. So it avoids roof-mounting and suits some layouts - with space and access. So internal siting and no roof work, with space and panels planned. This is general commentary on system design.

A competent extraction designer or installer - assessing your building, roof, duct route, space, noise and cleaning access - should make or advise the choice; it's a design decision for your specific premises, not a rule of thumb. Choosing the fan position is a design decision that should be made by a competent extraction system designer or installer, who can assess your specific premises and weigh the factors together: the building and roof (and its access), the duct route and discharge point, the available internal space, the noise considerations and surroundings, and - importantly - how the fan will be cleaned and maintained over its life. They can then recommend the position that best fits your layout while keeping the fan cleanable. This page is general commentary on how the choice weighs up, to inform the discussion - not a specification for any particular system. So involve a competent designer/installer for the actual decision, and make sure long-term cleaning access is part of what they consider. So a competent designer/installer, for your premises. So a qualified designer, assessing your specific building. This is general commentary on system design, not a specification for your system.

It's possible as a system change but it's a significant design and installation job, not a simple swap - it affects the ductwork, discharge, space and access; if you're considering it, get a competent designer/installer to assess it for your premises. Changing an extract fan from roof-mounted to in-line (or the reverse) is not a simple swap - it's a significant alteration to the extraction system. Moving the fan affects the ductwork routing and the discharge point, the space needed (internal space for an in-line fan; roof space and mounting for a roof fan), the noise situation, and the cleaning access - so it's a design and installation project, needing proper assessment and work, not just relocating a unit. If there's a reason to consider it (a persistent problem, a building change, or wanting to improve cleaning access), the right step is to have a competent extraction designer or installer assess your system and premises, and advise whether and how it makes sense. So it's possible, but it's a considered system change for a professional to assess and carry out - not a quick alteration. So possible, but a significant design/installation job to assess properly. So yes, but it's a major change - get it assessed. This is general commentary on system design, not a specification for your system.