Guide from the team
What actually happens when an engineer surveys your ductwork: what gets measured, photographed and recorded, and what the written output looks like.
Published 8 September 2026
Before any ventilation system is cleaned to TR19, it needs to be surveyed. The survey is where an engineer establishes what your system is, what condition it is in, and what a compliant clean involves. Instead of a quote based on a phone description, you get a scope based on what is physically inside your ductwork. Here is what happens, step by step.
The engineer starts by tracing the ductwork from plant to terminals: where the runs go, what they serve, and where the air handling units, fans and filters sit. For a commercial kitchen, that means following the kitchen extract system from the canopy to the extract fan and discharge point.
Access is reviewed at the same time, because access decides whether a system can be cleaned to standard at all. TR19 cleaning works through access panels along the duct, and many systems, particularly older ones, were installed without enough of them. The engineer records where existing panels are, where new ones would be needed, and any parts of the system that are difficult to reach: risers boxed into walls, runs above fixed ceilings. That is the information the survey exists to capture: a quote that ignores access problems is a quote for a clean that will not happen.
A TR19 survey is a measuring exercise, not an eyeball exercise. The engineer opens the system at representative points and assesses the deposit on the internal surfaces. For general supply and extract ventilation and ductwork, that means assessing dust and debris levels against the cleanliness criteria in TR19. For kitchen extract, it means measuring the grease layer on the duct wall, because grease depth determines both the fire risk and the urgency of the clean. Our companion article on how grease is measured in kitchen extract covers that measurement in detail.
Photographs are taken throughout: the internal condition of the duct at each opening point, the plant, the canopy and filters in a kitchen system, and anything needing attention beyond cleaning, such as a fan caked in deposit. Those photographs go into the survey report, so the condition of the system is evidenced rather than described.
Deposit assessment turns the survey from a look around into a compliance document. The engineer compares what is measured against the thresholds in the guidance: when a system needs cleaning, and how the measured grease level relates to fire risk. Usage matters too. TR19 Grease links cleaning frequency to how heavily the kitchen is used: 12 to 16 hours of cooking a day calls for a clean every 3 months, 6 to 12 hours every 6 months, and 2 to 6 hours every 12 months. The survey establishes where your kitchen sits on that scale, so the recommended frequency reflects your actual operation. For a fuller treatment of the intervals, see how often kitchen extract ductwork should be cleaned.
An honest survey records its own limits. If a section of ductwork cannot be accessed on the day, the engineer notes it as unsurveyed rather than guessing at its condition. A survey that silently skips the awkward sections produces a clean that silently skips them too, and the certificate quietly covers less than you think. Recording unaccessed areas keeps the documentation truthful and flags where access panels need to be installed, so the whole system can be brought into the cleaning regime.
After the visit you receive a written report setting out:
The report is yours to keep whether or not you proceed. It records the state of your system, feeds your fire risk assessment, and gives you a like-for-like basis for comparing quotes.
Our TR19 surveys are free, and accepting one does not commit you to anything. The engineer surveys the system, you receive the report and the price, and the decision after that is yours. If the system does not need cleaning yet, the report says so.
Request a free survey or ask for a TR19 quote and we will arrange a visit. And if you already have a TR19 report from a previous contractor, send it over and we will read it: it often tells us most of what we need to know before anyone sets foot on site.
It depends on the size and complexity of the system. A single kitchen extract run might be surveyed in an hour or two, while a large building with multiple air handling units and long duct runs takes longer. The engineer will give you a realistic estimate when the visit is booked.
Very little. The survey is an inspection, not a clean: the engineer opens access panels, measures and photographs the internal condition, and closes everything up afterwards. In kitchens, the visit can usually be timed outside service hours so cooking is not interrupted.
Yes. Our surveys are free and carry no obligation. You receive the written report, the findings and the price whether or not you go ahead with the cleaning.
The engineer records any unaccessed sections in the report rather than guessing at their condition. Where access panels are missing, the quotation includes installing them, so the whole system can be cleaned and certificated. Unaccessed areas are a common finding and a solvable one.
Send us your existing report or book a free survey. A named engineer replies within 24 hours.