TR19 & standards
A clean you can't evidence is a clean an insurer can question. This is the proof TR19 Grease expects you to hold.
The short answer
Under TR19 Grease, verification is the proof step: before-and-after photographs taken from the same positions, grease-thickness readings across the system, and a certificate registered through BESA's BESCA scheme. Without it, you have a cleaned system but no way to show it - which is the part that matters after a fire.
What a verification pack contains
A proper post-clean report is built from a few consistent parts. Before-and-after photographs are taken from identical positions so the change is genuinely comparable, not two flattering angles. Grease-thickness readings are recorded at set points through the ductwork, before and after, so the numbers back up the pictures. A system schematic shows what was cleaned, and any sections that could not be reached are listed with a recommendation to fix the access.
On top of the report sits the certificate. The contractor registers the clean on BESA's BESCA Ventilation Hygiene Elite portal, logging where, when, and whether the system was fully or partially cleaned. That registration generates a BESCA certificate that supports the report - the independent thread that makes it more than a self-marked homework sheet.
Why 'looks clean' isn't verification
The point of verification is to remove opinion. A duct can look clean at the access hatch and still hold grease three metres in. Readings taken through the run, ideally showing a cleaned surface down near the sub-50-micron mark, turn a judgement call into a record. Photographs from fixed points stop the after shot being a different, cleaner section than the before.
This is also why the technician matters. TR19 Grease expects the person taking readings and signing off to hold the BESA Grease Hygiene Technician qualification, so the verification is done by someone trained to the specification rather than eyeballed.
The BESCA layer adds independence on top of that competence. Contractors who certify to TR19 Grease register on the Ventilation Hygiene Elite scheme and are audited - BESCA periodically reviews a sample of members' post-clean reports and can revoke membership for poor work. So a certificate is not just the contractor's own word; it sits inside a scheme that checks the work behind it. For you, the value is practical: when a fire officer or insurer asks for evidence, a report with fixed-point photos, paired micron readings and a registered certificate usually answers most of the questions on the spot, and keeps them with the fire safety records where they belong.
The limit
Verification proves what was cleaned - it cannot invent access that isn't there. If large sections were unreachable, an honest report says so and records a partial clean, which is not the same as compliance. A certificate is only as complete as the clean behind it, so read the inaccessible-areas notes as closely as the headline. Fixing access is usually what turns a partial into a full, compliant result.
Questions
It is the documented proof of a clean: before-and-after photos from fixed points, grease-thickness readings, a system schematic, notes on any inaccessible areas, and a BESCA-registered certificate.
A certificate generated when the contractor registers the clean on BESA's BESCA Ventilation Hygiene Elite portal, recording where and when the work was done and whether the system was fully or partially cleaned. A small fee applies per certificate.
So the result can be judged like for like. Photos from identical positions show the actual change in each section, rather than relying on the technician's word or two unrelated angles.
No. TR19 Grease is built to remove opinion. Without readings, photos and a certificate you cannot demonstrate compliance to a fire risk assessor or insurer.
A technician holding the BESA Grease Hygiene Technician (GHT) qualification, working for a contractor registered on the BESCA VHE scheme.
Phoenix Duct Clean · by the numbers
Every job we do comes with photographic proof, thickness readings and a BESCA-registered certificate - the paperwork that answers the questions before they're asked.