The Hidden Fire Risk in Commercial Kitchens: How TR19 Grease Builds Up in Extraction Systems

Commercial kitchens produce heat, smoke, vapour and grease every day. Much of this is captured by the kitchen extraction system, which means grease and cooking deposits can gradually accumulate inside canopies, filters, fans and extraction ductwork.

When these deposits are not properly managed, they can become a significant fire-safety concern.

TR19 Grease provides guidance for managing grease contamination within commercial kitchen extraction systems and establishing an appropriate approach to inspection, cleaning and post-clean verification.

What Is TR19 Grease?

TR19 Grease is a recognised industry guide for managing grease contamination in commercial kitchen extraction systems.

It provides a structured approach to assessing grease deposits and determining appropriate cleaning requirements. The aim is to help keep extraction systems properly maintained and reduce the accumulation of combustible grease within the system.

The exact cleaning requirements depend on factors such as the type of cooking, operating hours, system design and level of grease production.

How Does Grease Build Up in Kitchen Extraction Systems?

During cooking, airborne grease and cooking vapours are drawn into the extraction system.

Some grease is captured by the filters, while other deposits can settle on internal surfaces throughout the extraction system.

Over time, grease can accumulate on:

• Canopies

• Grease filters

• Extraction fans

• Ductwork

• Plenums

• Internal extraction components

The amount of build-up can vary considerably between different commercial kitchens.

For example, kitchens using frying, grilling or other high-grease cooking processes may produce deposits more quickly than kitchens with lower-intensity cooking methods.

Why Is Grease a Fire Risk?

Grease is combustible. When significant deposits build up inside kitchen extraction ductwork, they can provide additional fuel if ignition occurs.

The London Fire Brigade has repeatedly warned restaurant and takeaway operators about the risk of dirty extraction ducting. In a May 2026 restaurant fire in Lee Green, firefighters reported that the fire was believed to have been caused by a build-up of grease in the ducting.

London Fire Brigade also advises restaurants and takeaways to have extraction ducting cleaned regularly because grease build-up can increase the risk of ducting fires.

This makes fire safety in commercial kitchens an important consideration when planning extraction system maintenance.

What Does TR19 Grease Cleaning Involve?

A professional extraction cleaning service may involve cleaning accessible areas of the kitchen extraction system and removing accumulated grease and cooking deposits.

Depending on the system, this can include:

• Kitchen canopy

• Grease filters

• Extraction plenum

• Fans

• Internal ductwork

• Access panels

• Other accessible components

The cleaning method should be appropriate for the system and capable of achieving the required post-clean verification.

The London Fire Brigade's kitchen extract guidance specifically references TR19 Grease for post-clean verification and notes that cleaning frequency should be sufficient to prevent grease deposits from exceeding specified limits.

How Often Should a Commercial Kitchen Extraction System Be Cleaned?

There is no single cleaning frequency that applies to every commercial kitchen.

The appropriate frequency depends on factors such as:

• Type of cooking

• Hours of operation

• Amount of grease produced

• Extraction system design

• Previous inspection findings

• Level of grease contamination

Kitchens that produce large amounts of fried or chargrilled food may require more frequent cleaning than kitchens using lower-intensity cooking methods. London Fire Brigade guidance specifically notes that cleaning frequency should reflect usage and grease production.

A professional assessment can help determine the appropriate maintenance approach for your system.

Why Is Regular Extraction Cleaning Important?

Regular commercial kitchen extraction cleaning can help businesses:

• Reduce grease accumulation

• Support fire-risk management

• Maintain cleaner extraction systems

• Support effective ventilation

• Identify maintenance issues

• Maintain appropriate cleaning records

• Support ongoing kitchen safety procedures

HSE guidance on effective kitchen ventilation recommends suitable access to ductwork so it can be regularly cleaned and grease accumulation can be prevented. It also highlights the importance of ventilation systems being easy to clean and maintain.

Which Businesses Need Kitchen Extraction Cleaning?

Professional kitchen extraction cleaning may be relevant to:

• Restaurants

• Pubs

• Takeaways

• Hotels

• Care homes

• Schools

• Hospitals and healthcare facilities

• Food production facilities

• Commercial catering kitchens

The cleaning requirements will depend on the type of cooking and the extraction system installed.

What About Canopies and Filters?

The canopy and filters are important parts of the extraction system and should not be overlooked.

Filters can collect grease during normal cooking operations, while grease can also accumulate around the canopy and extraction plenum.

London Fire Brigade recommends regular cleaning of kitchen ducting and also highlights the importance of keeping the hob, cooker hood and extractor fan clean.

Regular day-to-day cleaning by kitchen staff can therefore complement periodic specialist extraction cleaning.

Why Are Access Panels Important?

Access is essential when inspecting and cleaning internal extraction ductwork.

Without suitable access points, it can be difficult to properly inspect and clean internal surfaces.

London Fire Brigade guidance states that access panels should provide appropriate access for regular cleaning and inspection of kitchen extract systems.

Where an existing system has inadequate access, an appropriate access solution may need to be considered.

What Documentation Should Businesses Keep?

After professional extraction cleaning, businesses should maintain appropriate records.

Depending on the service, documentation may include:

• Cleaning date

• Areas cleaned

• Inspection findings

• Photographic evidence

• Cleaning results

• Post-clean verification

• Recommendations

• Relevant reports or certification

Good documentation gives facilities managers and business owners a clear history of maintenance and helps with future planning.

5 Signs Your Kitchen Extraction System Needs Attention

Watch for these common warning signs:

1. Excessive Grease Build-Up

Visible grease around the canopy, filters or accessible extraction components can indicate that the system needs attention.

2. Strong or Unusual Odours

Persistent smells may indicate contamination or other ventilation issues.

3. Reduced Airflow

Poor extraction performance can indicate contamination or another system problem.

4. Heavy Grease Deposits

Significant deposits within accessible parts of the system should be assessed professionally.

5. Failed or Unsatisfactory Inspection

If an inspection identifies excessive contamination or other maintenance concerns, professional cleaning may be required.

How Can Businesses Improve Fire Safety in Commercial Kitchens?

Kitchen extraction cleaning should form part of a wider fire-safety and maintenance programme.

Businesses should also consider:

• Keeping cooking equipment clean

• Maintaining grease filters

• Keeping extraction systems clean

• Maintaining appropriate fire-risk assessments

• Ensuring suitable access to ductwork

• Keeping maintenance records

• Following appropriate manufacturer and professional guidance

London Fire Brigade recommends regular cleaning of kitchen extraction ducting and keeping fire-risk assessments up to date.

Final Thoughts

Grease accumulation inside a commercial kitchen extraction system should not be ignored.

A properly managed extraction system can help businesses reduce avoidable grease build-up and support a wider approach to kitchen fire safety.

TR19 Grease provides a recognised framework for managing grease contamination and post-clean verification within commercial kitchen extraction systems.

At Canopy Cleaning Services, we provide professional commercial kitchen extraction, canopy, filter and ductwork cleaning services for businesses across London and surrounding areas.

If you are concerned about grease build-up or the condition of your extraction system, contact our team to discuss your requirements and request a quotation.

Need Professional TR19 Grease Cleaning?

Contact Canopy Cleaning Services today for a professional quotation.