Phoenix Journal · Ductwork
Kitchen extract in a listed building has to be cleaned to the same fire-safety standard as any other - but reaching it without breaching heritage law takes planning most contractors skip.
Heritage · Compliance
A restaurant in a Grade II former coaching inn booked a routine extract clean, and by the end of the day the owner had two problems instead of none - a duct that still was not clean, and a heritage breach that could have ended in court.
Here is how it unfolded. The kitchen sat in the oldest part of the building, and the extract run climbed through a boxed-in void, turned a long horizontal leg above a lath-and-plaster ceiling, and vented up a disused chimney breast. There were no access panels anywhere along it. The extract had been ducted years earlier by a fit-out contractor who never fitted hatches, so nobody had ever properly cleaned the horizontal section.
The cleaning crew arrived, opened the canopy, and found they could reach perhaps the first metre and nothing beyond it. Under pressure to finish the job on the day, someone made a decision that felt practical and turned out to be expensive - they cut a hatch through the historic ceiling and prised out a section of old panelling to get a hand and a brush into the run. No drawings, no conservation officer, no listed building consent. The grease deeper in the duct was never touched, and the hole in the fabric was very much noticed.
Two separate failures braided together here, and each one was avoidable on its own.
The first was a compliance gap. Commercial kitchen extract has to be cleanable along its whole length, because grease does not settle politely near the hood - it carries and deposits right through the system. BESA's TR19® Grease standard, released as a standalone document on 15 April 2024, treats this as fire risk management, not housekeeping. In practice that means access panels at roughly every two metres and at every bend, so a technician can inspect and clean each section and then verify it. A duct with no panels is, by definition, a duct that cannot be shown to be clean. The unreachable horizontal leg was the exact place grease had been building for years, and it was the exact place the crew could not get to.
The second failure was the one with the criminal weight behind it. Cutting a hatch through a lath-and-plaster ceiling and removing panelling is an alteration to a listed building. Listed building consent is governed by the Planning (Listed Buildings and Conservation Areas) Act 1990, and it applies to internal works just as much as external ones wherever they affect the building's special character. Carrying out those works without consent is a criminal offence under Section 9 of the Act - and it is an absolute offence, meaning the prosecution does not have to prove anyone intended any harm. Penalties run up to an unlimited fine and two years' imprisonment on indictment, and the local authority can serve an enforcement notice compelling the owner to put the fabric back at their own cost.
So the owner was left exposed on both fronts at once. The extract still failed a TR19® Grease inspection because most of it had never been reached, and the "solution" had created an unauthorised alteration to protected fabric. The person who caused the works to be carried out can be prosecuted alongside the owner, so the contractor was in the frame too.
Grease accumulation is measured, not guessed at. Technicians use a Wet Film Thickness Test, reading deposit depth in microns, and that reading drives how often the system needs cleaning - a heavy-use kitchen running twelve to sixteen hours a day may need it quarterly. None of that measurement is possible if half the duct is sealed inside historic joinery, which is why access and heritage have to be solved together rather than one at a time.
A documented TR19® Grease programme is also the practical evidence a duty-holder relies on under the Regulatory Reform (Fire Safety) Order 2005 and the Health & Safety at Work Act 1974. Insurers increasingly ask to see it after a fire. In an old building, that matters twice over, because a grease fire that starts in the extract does not stay in the extract - it follows the concealed timber voids and flues that older structures are full of. If you want the detail on that mechanism, it is worth understanding how fire spreads through building voids and ductwork before you decide how much risk you are carrying.
The right sequence is slower on paper and far faster in reality, because it never ends in an enforcement notice. This is the approach we would take on a protected building.
There is a bigger principle underneath all of this. In a listed building the instinct to rip out awkward old ductwork and replace it wholesale is usually the wrong one - it disturbs protected fabric, triggers more consent, and is rarely necessary. A well-cleaned system almost always beats a torn-out one, which is the heart of the environmental case for cleaning over replacing ductwork.
Questions
If the panels alter fabric that contributes to the building's special character - original joinery, lath-and-plaster ceilings, historic masonry - then yes, you almost certainly do. Listed building consent covers internal works as much as external ones. It is free to apply for, and cutting openings without it is a criminal offence under the Planning (Listed Buildings and Conservation Areas) Act 1990, so speak to your local authority's conservation officer before any work begins.
Yes. TR19 Grease applies to the kitchen extract regardless of the building's status, and a listed structure is not exempt from fire-safety obligations. The challenge is access rather than the clean itself, so the run is surveyed first and reached through existing openings wherever possible, with any new panels placed sympathetically and under consent. Each section is then cleaned and verified so the whole system can be shown to be compliant.
Both the owner and the person who caused the works can be prosecuted, and the offence is absolute - intent does not have to be proven. The local authority can also serve an enforcement notice requiring the fabric to be restored at your cost, with no time limit on when it can act. That is why the survey and consent steps matter as much as the cleaning, and why you should use a contractor who understands heritage constraints.
Phoenix Duct Clean · by the numbers
Phoenix surveys and cleans kitchen and building ductwork to the TR19 standard - measured, cleaned and certificated, UK-wide.