Phoenix Journal · Ductwork
The extract fan on your roof is easy to forget until a service falls due - and then reaching it becomes one of the highest-risk tasks on the whole site. Here is how to plan roof-fan access that keeps engineers safe and keeps you the right side of the law.
The fan that pulls grease-laden air out of your kitchen almost never sits somewhere convenient.
It lives on the roof - bolted to a plinth, humming away above a flat felt deck or a run of profiled sheeting, often within a stride or two of an unguarded edge. On the ground it is easy to forget it is there. Then a service visit comes due, an engineer needs to reach it, and a small maintenance job quietly becomes one of the highest-risk tasks anyone will carry out on your premises that year.
Falls from height remain the single biggest cause of workplace deaths in the UK, and roof-mounted extract plant sits right in the middle of that statistic. The Health & Safety Executive has published cautionary cases that read almost identically to a routine fan clean: one worker suffered permanent spinal injuries after falling almost three metres while cleaning extraction fans on a roof he had reached by climbing up at the low end and walking along the edge to the fan housings. There was no edge protection, no risk assessment, and no safe system of work. None of it was exotic. It was a fan on a roof, the same as yours.
A roof fan earns its place up there. Putting the motor at the discharge point keeps the whole duct run under negative pressure, so any leaks pull inward rather than weeping grease down through the building, and it moves noise and heat away from the kitchen. Those are good reasons - the trade-off is simply that every drop of maintenance now happens in the one environment the law treats most seriously. If you are still deciding where the fan should sit, it is worth reading how roof fans compare with in-line fans before the plinth goes in, because access is part of that decision and not an afterthought.
The governing law is the Work at Height Regulations 2005, and its heart is Regulation 6 - a strict hierarchy you are expected to work through in order, not pick from. First, avoid working at height where it is reasonably practicable to do so. Where you cannot avoid it, prevent falls using an existing safe place of work or collective protection before you reach for anything personal. And where a fall still cannot be prevented, minimise the distance and consequences of one. Collective measures - guardrails, a proper platform, edge protection that protects everyone on the roof at once - always rank above personal measures such as a harness, because a guardrail does not depend on someone clipping on correctly every single time.
For a fan clean, "avoid" rarely means skipping the roof, but it can mean designing the job so more of it happens from a safer position - servicing components at deck level, or reaching the unit from a mobile elevating work platform with intact guardrails rather than standing on the roof at all. The point is that the roof surface is the last resort, not the default.
The HSE is blunt on this: all roofs should be treated as fragile until a competent person has confirmed they are not. Rooflights, fibre-cement sheets, weathered felt over old decking and corroded metal profiles will all take your weight right up until the moment they do not, and a fall through a fragile surface is often more serious than a fall from an edge. Grease makes it worse - the ground around a kitchen discharge fan is frequently coated in a slick, invisible film that turns a sound roof into a skating rink, particularly after rain or in cold weather. Before anyone steps out, the surface itself has to be part of the assessment.
Once you accept the fan has to be reached, the job becomes about choosing the right protection and the right equipment, then writing it down so it happens the same way every visit. This is where good intentions usually fall apart - not because anyone means to cut corners, but because the safe method was never agreed in advance and the person on the roof improvises.
Where the fan sits near an edge, permanent or temporary edge protection is the strongest answer because it guards everyone, needs no training to "use", and cannot be forgotten. HSE guidance describes the shape of it clearly: a main guardrail at least 950 mm above the edge, a toe board where objects could be kicked off, and intermediate rails set so no gap exceeds 470 mm. If a fixed guardrail around the plant is not present, that gap in your provision is worth closing permanently - it pays for itself the first time the fan needs attention and keeps paying at every clean, filter change and belt check thereafter.
Where collective protection at the edge is not reasonably practicable, a mobile elevating work platform is often the safest way to bring an engineer up to the unit without loading the roof surface at all. Both MEWPs and any powered access count as lifting equipment, so they fall under LOLER 2005 as well as PUWER 1998, meaning they need to be in date for thorough examination and operated by someone trained and competent. Ladders are not banned, but under the hierarchy they are only justified for short-duration, low-risk access - reaching a hatch, not standing on a rung to wrestle a greasy impeller.
The regulations put the duty on whoever controls the work to plan it, supervise it and have it carried out by people who are competent - or being trained under supervision. For a roof fan that means a task-specific risk assessment and method statement that names the access route, the fall protection, the rescue plan if someone does end up suspended in a harness, and the weather limits that stop the job. It also means the fan itself being isolated and locked off before anyone opens it, because a fan that restarts under someone's hands is its own serious hazard, quite apart from the drop. If you are reviewing the whole extraction setup, understanding how commercial kitchen fans are sized helps explain why the unit is as large, heavy and awkward to reach as it is - and why two people are often needed rather than one.
None of this is meant to make a fan clean feel forbidding. It is the difference between a task that is simply booked, done and signed off, and one that turns into the HSE case study nobody wants their name on. Get the access, the protection and the plan right once, and every future visit to that roof becomes ordinary - which, for work at height, is exactly what good looks like.
Questions
If the fan sits near an unprotected edge - as a rule of thumb, within about two metres - then yes, you need to prevent a fall before anyone starts work. Under the Work at Height Regulations 2005 collective protection such as a guardrail ranks above a personal harness, because it protects everyone on the roof without depending on someone clipping on correctly. Where a fixed guardrail is not practicable, a mobile elevating work platform or temporary edge protection can achieve the same thing for the duration of the visit.
A ladder can be justified only for short-duration, low-risk access, such as climbing to a roof hatch or fixed access point. It is not a working position for a task like cleaning or removing a greasy impeller, where you need both hands, stable footing and time on the plant. In that case the hierarchy points you towards a proper platform, a MEWP or protected roof access rather than balancing on a rung.
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