Grease in extract ductwork is the fire risk insurers care most about — and the one you can’t see from the kitchen. We measure it in microns to TR19® Grease, certify where you stand, and prove that cleans actually worked.
Every hour of cooking loads the extract system with another film of grease — and a grease-lined duct is a fuse running from the kitchen through the rest of the building. Extract ductwork is one of the best-documented routes for catastrophic fire spread in hospitality, and under the Regulatory Reform (Fire Safety) Order 2005 the responsible person must be able to show that risk is being managed.
Insurers have moved from asking to insisting: TR19® Grease-compliant maintenance is now written into many kitchen policies as a condition of cover, and claims have been cut down or refused after duct fires where no maintenance records existed. The standard is specific — mean grease deposits must stay below 200 microns between cleans — and the only way to know where you stand is to measure.
Wet Film Thickness Testing with a calibrated comb gauge at representative points across canopies, ductwork and fans — grease depth in microns, reported against the TR19® Grease thresholds: 200-micron system mean, 500-micron local spot-clean trigger, sub-50-micron post-clean target.
Where access is limited or the system’s history is unknown, we combine grease testing with CCTV ductwork surveys — camera evidence of internal condition, blockages, damage and unrecorded modifications alongside the measured grease readings.
After any clean — ours or an incumbent contractor’s — we re-test and certify against the post-clean standard. Dated, photographic, measured records for your fire risk assessment file and your insurer, so renewal questions get answered with evidence rather than assurances.
Where testing shows a system over threshold, our ventilation hygiene team carries out TR19® Grease-compliant cleaning — verified with before-and-after WFTT measurements, and access panels installed where the system can’t currently be reached.
Those are the TR19® Grease benchmark intervals — but they’re a starting point, not a substitute for measurement. Testing between cleans shows whether your interval is genuinely holding you under 200 microns: some kitchens need cleans more often, others are buying cleans they don’t yet need. Either way, you decide on numbers.
Testing and cleaning are carried out in line with BESA TR19® Grease, the specification for fire risk management of grease accumulation in kitchen extract systems, with results reported against its measured thresholds.
And because we’re fire and security specialists first, a grease test with us looks at the whole fire picture — compartmentation and fire-stopping where ducts pass through walls, damper condition, and the state of the detection and suppression protecting the kitchen itself. One visit, one consolidated compliance position — across restaurants and hotels, healthcare catering and education kitchens.
TR19® Grease is the Building Engineering Services Association (BESA) specification for managing the fire risk from grease in kitchen extract systems — the recognised UK benchmark that fire risk assessors and insurers reference. It sets measurable cleanliness thresholds, verification methods and cleaning intervals for extract canopies, ductwork and fans.
TR19® Grease requires the mean grease deposit across the system to stay below 200 microns between cleans — roughly half the thickness of a business card. Any local reading of 500 microns or more calls for immediate spot cleaning, and after a compliant clean the system mean should be below 50 microns. All three are verified by measurement, not by eye.
TR19® Grease links the interval to daily cooking hours: heavy use (12–16 hours a day) every 3 months, moderate use (6–12 hours) every 6 months, and light use (2–6 hours) every 12 months. Testing evidences whether the interval you’re on is actually right for your kitchen — some sites need cleans more often, others are paying for cleans they don’t yet need.
Increasingly, yes. Many commercial kitchen policies now make TR19® Grease-compliant maintenance a condition of cover, and claims following extract-duct fires have been reduced or refused where the system wasn’t maintained and no records existed. Our reports and certificates give you measured, dated, photographic evidence to hold on file.
The Wet Film Thickness Test measures grease deposit depth in microns using a calibrated comb gauge, taken at representative points across the canopy, ductwork and fan. It is the TR19® Grease method for demonstrating a system is within the 200-micron threshold — and for proving a clean achieved the post-clean standard.
Yes — through our ventilation hygiene service. Every clean is verified with before-and-after WFTT measurements, so the certificate you file is backed by numbers, not just an invoice.
A named engineer, not a call centre, comes back within 24 hours. Tell us the kitchen, the cooking hours and the last clean date, and we’ll scope the right test.