It's one of the most common questions we get from restaurant owners and kitchen managers across London: how often do we actually need to have our extraction system cleaned? The answer depends on how heavily your kitchen is used and what type of cooking you carry out — but there is a formal standard that sets out the minimum requirements, and it's one your insurer and Environmental Health Officer will expect you to follow.
That standard is TR19, published by BESA (the Building Engineering Services Association). Here's what it says — and what it means in practice for your kitchen.
The TR19 Cleaning Frequency Guide
TR19 categorises commercial kitchens by usage level and sets a minimum cleaning frequency for each. The three categories are:
High Usage — Every 3 Months
Kitchens that operate for 12 to 16 hours per day, or those that use heavy-duty cooking equipment such as woks, chargrills, solid-top ranges, or deep fat fryers at high volume. This includes most fast-food operations, busy independent restaurants with long service hours, and hotel kitchens serving breakfast through to dinner.
At this intensity, grease accumulates in ductwork quickly. A 3-month cleaning cycle is the minimum to keep grease levels below the threshold at which fire risk becomes significant.
Medium Usage — Every 6 Months
Kitchens operating for 6 to 12 hours per day, using a standard mix of cooking equipment. Most independent restaurants, pubs with kitchen operations, and casual dining venues fall into this category. A bi-annual clean — typically one at the start of spring and one in the autumn — is the norm for this type of operation.
Low Usage — Every 12 Months
Kitchens operating for fewer than 6 hours per day, or those carrying out light cooking such as reheating, sandwich preparation, or light frying. Cafés, delis, and office canteens with limited cooking output are typically low-usage sites. An annual clean is the minimum requirement.
How Is Usage Assessed?
Usage is assessed based on a combination of daily operating hours and the type of cooking equipment in use. A kitchen running long hours but only using combination ovens and bain-maries may still qualify as medium usage. A kitchen open for only 8 hours but running three chargrills and a fryer bank continuously would almost certainly be classified as high usage.
When Fan Rescue carries out an initial site visit, we assess the kitchen against TR19 criteria and advise on the correct cleaning frequency. This is included as part of any quotation — there's no charge for the assessment.
What Happens If You Clean Less Frequently Than Required?
This is where it gets serious. There are three key areas of risk if your extraction system is not cleaned at the correct TR19 frequency:
1. Your Insurance May Be Invalid
Most commercial property and business interruption insurance policies for food businesses include a condition that extraction systems must be maintained and cleaned in line with TR19. If a fire starts in or around your extraction system and you cannot produce a TR19 certificate showing cleaning was carried out at the required frequency, your insurer may refuse to pay out. This is not a theoretical risk — it happens.
2. You Could Fail an EHO or Fire Safety Inspection
Environmental Health Officers and Fire Safety Officers can and do ask for extraction cleaning certificates during inspections. A failure to produce valid documentation — or a visual inspection that reveals obvious grease build-up — can result in an improvement notice, a requirement to cease certain cooking operations, or in serious cases, closure.
3. Increased Fire Risk
Grease is highly flammable. In London, a commercial kitchen extraction system catches fire, on average, every nine days. Grease build-up in ductwork is the primary cause. A fire that starts in a dirty duct can spread to the roof void, adjacent units, or the wider building within minutes. Regular cleaning is not a box-ticking exercise — it is a genuine safety measure.
What Does a TR19 Clean Actually Cover?
A TR19-compliant clean carried out by Fan Rescue covers the full extraction system from the canopy filters through to the fan unit and termination point, including:
- Canopy interior and baffle filters
- Full ductwork run, including bends and access panels
- Fan unit (blades, housing, motor casing)
- Termination grille or weather louvre at roof or external wall level
On completion, we provide:
- A signed TR19 Certificate of Hygiene
- Photographic evidence of the system before and after cleaning
- A report noting any defects, damage, or areas requiring attention
This documentation is what your insurer, EHO, and fire officer will ask for. Keep it on file and make sure the next clean is booked before the certificate expires.
How to Know When Your Next Clean Is Due
The TR19 certificate issued after each clean will state the date of the clean and the recommended date for the next one, based on the usage category assessed at the time. If you're unsure when your system was last cleaned, or if you've taken over a kitchen and there are no records available, we'd recommend booking a clean and starting a fresh compliance record from that point.
Fan Rescue clients on service agreements receive automated scheduling reminders, so you never have to track it manually. If you have multiple sites, we manage the cleaning schedule centrally and coordinate access directly with your site managers.
Book a TR19 Duct Clean Across London
Fan Rescue is BESA-certified (HV020676) and carries out TR19-compliant extraction system cleans across London and the South East. We work with independent restaurants, hotel kitchens, pub groups, and multi-site restaurant chains.
To book a clean or get a quote, call us on 020 3308 2936 or email office@fanrescue.co.uk. We typically provide quotes within 24 hours and can accommodate urgent bookings where required.
Fan Rescue Ltd
Ability House, Unit 129, 121 Brooker Rd, Waltham Abbey EN9 1JH
Tel: 020 3308 2936 | BESA: HV020676 | F-Gas: FGAS2001890
