Commercial kitchens, whether in restaurants, hotels, or institutional catering facilities, operate in high-intensity environments. With constant frying, grilling, and roasting, these environments produce significant volumes of airborne grease, steam, and heat. Extraction systems serve as the lungs of these kitchens, working tirelessly to remove these by-products of cooking. However, over time, heavy use leads to an inevitable problem—grease build-up.
Grease accumulation in kitchen extraction systems can become a severe hazard. Not only does it decrease the efficiency of ventilation and contribute to unpleasant odours, but it also significantly increases the risk of fire. The build-up inside hoods, ductwork, filters, and fans provides a highly flammable fuel source. Consequently, maintaining a clean and efficient extraction system is not just a matter of hygiene—it’s a crucial component of fire safety and regulatory compliance.
Legal and Regulatory Considerations
In the UK, commercial kitchen operators are legally obligated to maintain their extraction systems in a clean and functional condition. This is stipulated under the Regulatory Reform (Fire Safety) Order 2005, which requires employers and building owners to ensure precautions are in place to reduce fire risk. Local council health and safety inspections often focus on grease management procedures. Furthermore, insurance companies may void fire-related claims if systems are not adequately cleaned.
TR19® Grease, a prominent industry guideline provided by the Building Engineering Services Association (BESA), lays out standards for cleaning kitchen ventilation systems. Adherence to these standards ensures regulatory compliance and forms part of a defensible due diligence process in the event of fire or inspection.
Identifying Heavy-Use Systems
The intensity of use is a prime factor in determining how often systems should be cleaned. TR19® defines heavy use as a system operating for 12-16 hours per day. In such kitchens, extraction systems can become heavily laden with grease in remarkably short timeframes. This makes routine monitoring and timely cleaning essential.
Indicators of a system requiring attention include visible grease on filters and hoods, slow ventilation response, excessive fan noise, and the release of cooking odours back into the kitchen or dining areas. Subtle signs should not be overlooked, and professional assessments at regular intervals can provide an objective view of system condition and cleaning needs.
Surface Cleaning vs Deep Cleaning
There is a fundamental distinction between surface-level cleaning and comprehensive system cleaning. Day-to-day degreasing of hoods, canopies, and removable filters can often be managed by trained kitchen staff using off-the-shelf degreasers and cleaning tools.
However, deep cleaning—which includes ductwork, fan units, and less accessible components—requires specialists with the tools, chemicals, and training to perform a thorough job. Surface cleaning may keep visible areas presentable, but internal ducting—the hidden zones—requiring specialised methods, often contain the most dangerous grease deposits.
Techniques for Effective Grease Removal
To eliminate grease effectively, a range of techniques and tools are employed, each suited to different levels of contamination and components of the extraction system.
Manual Scraping
This is one of the oldest and most direct techniques but remains essential. Trained technicians access large, flat ductwork surfaces or canopy interiors and physically scrape off thick layers of congealed grease using metal scrapers or putty knives.
Manual scraping serves as the first stage in many deep cleans, especially where the grease build-up is heavy. It allows technicians to remove bulk contamination before applying chemical treatments. While labour-intensive, it is often the only way to combat neglected systems where grease has built up over months or even years.
Chemical Degreasing
Degreasing agents—specifically formulated for industrial kitchens—are employed to break down the fatty acids and polymerised oils that form stubborn deposits. These cleaners are alkaline-based and designed to penetrate the hardened layers of grease that manual scraping can’t fully remove.
The process typically involves spraying or brushing the chemical onto the target surface, allowing dwell time for the chemicals to react, and then scrubbing or rinsing them off. Technicians must select the correct agent for the severity and type of grease build-up and use personal protective equipment due to the strength of these chemicals.
Pressure Washing and Hot Water Systems
High-pressure washing using hot water can be extremely effective when paired with degreasing agents. The heat of the water helps to emulsify the grease, while the pressure agitates and removes debris from surfaces, leaving them clean and residue-free.
This technique is especially useful in cleaning duct interiors and fans, where mechanical scrubbing is impractical. Access panels are often installed in ductwork to allow technicians to reach otherwise inaccessible areas and perform high-pressure cleaning.
Steam Cleaning
For delicate or hard-to-reach areas, steam cleaning provides a powerful but less invasive solution. Superheated water vapour penetrates into small ducts and crevices, breaking down grease without the need for aggressive abrasives or chemicals.
Steam is particularly useful for sanitising as well, high temperatures ensure the elimination of bacteria and microbes, offering a hygienic finish. However, this method requires specialised equipment and training, and may not be suitable for substantial grease deposits without preparatory scraping.
Rotary Brush Systems
Used chiefly for ductwork, rotary brush systems comprise flexible shafts with brushes that are fed into the ducts, powered by an external motor. As the brushes rotate, they dislodge grease build-up from the inner walls. This process is often conducted in tandem with vacuum extraction to capture debris instantly and avoid redistribution.
Rotary systems can include camera attachments to allow technicians to see inside ducts, verifying the effectiveness of the clean as the brush operates. It’s a method especially useful in integrated cleaning programmes that document progress for compliance.
Foam Cleaning
Chemical foam applications are another modern approach gaining traction. The foam adheres to vertical and irregular surfaces, penetrating grease layers with greater consistency than liquid chemicals. It provides good cling time, ensuring the agent remains active on the surface long enough to break down resilient coatings.
Foam works well on vertical duct surfaces, canopy interiors, and behind baffle filters. After application and dwell time, the foam and residue are wiped or rinsed away, often followed by another inspection to ensure a complete clean.
Creating a Comprehensive Maintenance Plan
No single cleaning technique is sufficient alone; rather, optimal grease removal involves integrating various methods into a broad maintenance plan. This includes scheduled cleanings, daily wiping routines, interim maintenance, and professional inspections.
For high-use systems, a quarterly professional cleaning is recommended. Between these, kitchen staff should undertake visual checks, change or clean filters, and perform light degreasing of hoods and canopies. Usage logs and cleaning records should be maintained meticulously as part of health and safety documentation.
Custom schedules based on kitchen workflow offer better long-term success. For example, a commercial fish and chip shop may require more frequent extraction cleaning than a vegetarian café due to the volume of oil used.
The Importance of Professional Expertise
While it may be tempting to attempt internal cleans using in-house staff to save costs, this often leads to incomplete grease removal, hidden build-up, and potentially void insurance policies. Trained professionals bring with them a suite of tools and a depth of knowledge to not only remove the grease effectively but also document and certify the job in compliance with standards.
Certified grease removal companies in the UK often provide post-clean reports, including photographs, chemical datasheets, and certificates of hygiene. These can prove invaluable in the event of a fire investigation or insurance claim.
Sustainable and Eco-Conscious Cleaning
As environmental awareness becomes more prevalent, many companies are shifting toward sustainable practices in grease removal. Biodegradable degreasers, water recycling protocols, and waste-reduction measures are becoming standard in the industry.
Some firms now offer enzyme-based degreasing solutions, which use natural catalysts to break down grease molecules without the need for harsh chemicals. These methods, while often slightly slower, significantly reduce the environmental impact of commercial cleaning operations.
Kitchen operators seeking cleaning services should consider the environmental credentials of potential suppliers—not only to safeguard ecosystems, but also to demonstrate social responsibility to customers and stakeholders.
Conclusion
In busy commercial environments with heavy use, kitchen extraction systems are prone to rapid grease build-up. Meeting this challenge requires far more than casual surface cleaning. Through manual scraping, chemical applications, rotary brushes, and advanced steam or foam systems, trained professionals can ensure your ventilation operates at optimum capacity and abides by stringent legal standards.
A proactive approach, combining frequent inspection, in-house light cleaning, and regular deep cleans by accredited technicians, provides the most reliable path to safety and efficiency. It also protects businesses from costly damage, potential downtime, and legal exposure.
In the long term, investing in effective grease removal is not merely a compliance issue—it’s a cornerstone of operational excellence and a safe, hygienic kitchen.