Why commercial kitchen extract systems matter and how to keep yours safe, compliant and running efficiently
A well-maintained commercial kitchen extract system isn’t just a nice-to-have, it’s essential for safety, compliance, and the long-term performance of your equipment. Whether you're running a high-use commercial kitchen or a small café, your extract system works hard behind the scenes to keep your staff safe, maintain air quality, and protect your building.
In New Zealand, kitchen operators also carry the responsibility of staying compliant with SS9, AS 1668.2:2024, and annual BWOF (12A) requirements. Understanding how your extract system works, and how to maintain it properly can save you from fire hazards, costly repairs, and compliance issues.
At National Hood & Duct Cleaning, we specialise in full-system cleans nationwide, including canopy, filters, ducting, fans, and flues with IQP-ready reporting delivered within 24 hours.
Below, we break down why extract systems matter, the standards that govern them, and how proper maintenance keeps your kitchen safe and compliant.
Why Extract Systems Matter
A commercial kitchen without effective ventilation becomes a dangerous environment quickly. Your extract system removes heat, smoke, fumes, and airborne contaminants. Without it:
Harmful pollutants accumulate in the air
Grease builds up inside the canopy, filters, ducting, and fan
Staff are exposed to poor air quality
Fire risks increase dramatically
Grease buildup inside an extract system can ignite easily — and once it does, the fire can travel rapidly through the ducting. Regular cleaning and proper system design are crucial for preventing avoidable incidents.
Understanding SS9 and AS 1668.2:2024 Compliance
In New Zealand, commercial kitchen extract systems fall under SS9 (Mechanical Ventilation Systems) in the Building Warrant of Fitness requirements.
SS9: Your Legal Responsibility
To stay compliant, kitchen operators must ensure:
The extract system is cleaned and maintained within required timeframes
An Independent Qualified Person (IQP) can verify compliance annually
Documentation (12A forms, cleaning certificates, service logs) is up to date
AS 1668.2:2024: Ventilation and Cleaning Intervals
This standard outlines:
Design and performance requirements for extract systems
Safe ventilation rates
Cleaning intervals based on kitchen usage (high-use vs low-use)
Following AS 1668.2:2024 ensures your system operates safely and efficiently — and keeps you aligned with industry best practice.
The Impact of Proper Maintenance
Well-maintained systems:
Improve airflow and extraction performance
Reduce fire hazards
Protect staff from poor air quality
Extend the lifespan of fans, motors, and ducting
Reduce costs by preventing major repairs or replacements
A neglected system doesn’t just risk compliance — it costs you money.
What Maintenance Should Include
Here are the essential steps every commercial kitchen should follow.
1. Regular Filter Cleaning
Filters trap grease before it enters the ducting. They need regular cleaning to:
Maintain airflow
Prevent grease fires
Reduce strain on the exhaust fan
Dirty filters are one of the top causes of poor system performance.
2. Routine Ductwork Inspection
Ducts should be checked for:
Grease buildup
Blockages
Leaks
Damage to access hatches or joints
If grease reaches critical levels inside the ducting, it becomes a major fire hazard.
3. Fan Servicing
Your fan is the heart of the system. Proper maintenance ensures:
Efficient extraction
Smooth, quiet operation
Reduced vibration and strain
Longer equipment lifespan
Unusual noises, rattling, or reduced airflow can indicate serious issues.
4. Compliance Documentation
Accurate paperwork is essential for your BWOF.
Maintain:
Cleaning Certificates
Cleaning Reports
Service Logs with dates and notes
IQPs rely on this documentation to issue your 12A.
Inspection Checklist for Your Kitchen Hood
A thorough inspection should include:
Checking for grease buildup inside the flue
Ensuring the flue is clear of blockages
Listening for abnormal fan noises
Verifying filter cleanliness
Checking airflow performance
Although G4/AS1 does not specify exact exhaust flow rates, compliance is typically achieved by meeting AS 1668.2requirements or supplying a compliant design.
Cleaning Frequency: High-Use vs Low-Use Kitchens
Not all kitchens operate the same way, and neither should their cleaning schedule.
High-Use Kitchens
(large restaurants, fast food chains, stadiums, hotels)
Generate high levels of grease
Require more frequent cleaning
Are more likely to experience airflow issues and fire risks
A strict cleaning schedule is essential to stay safe and compliant.
Low-Use Kitchens
(small cafés, function spaces, occasional-use kitchens)
Produce less grease
Require less frequent cleaning
Still need regular inspections to ensure safety
Even low-use kitchens can fail compliance if maintenance is neglected.
AS 1668.2:2024 Cleaning Intervals
This standard outlines recommended cleaning frequencies for different system types and usage levels. Following these guidelines helps reduce risk and keep your BWOF process smooth.
What to Expect After a Professional Clean
A professional clean should leave your hood, filters, ducting, and fan:
Visibly free of grease
Operating with improved airflow
Running quietly, with less vibration
Ready for IQP sign-off
Quality providers (like National Hood & Duct Cleaning) will also supply:
A Cleaning Certificate
A detailed Cleaning Report
Before-and-after photos
These documents are essential for proving compliance.
Preparing for Your IQP Inspection
Before your IQP arrives, have the following ready:
Cleaning Certificate
Cleaning Report
Service Log with dates and paperwork attached
This ensures your system is inspection-ready and avoids delays in your annual BWOF.
Final Thoughts
Your commercial kitchen extract system is one of the most important — and most overlooked — components of your business. With proper maintenance, regular cleaning, and the right documentation, you can:
Keep your kitchen safe
Protect your staff
Reduce fire risks
Stay compliant with SS9 and AS 1668.2:2024
Extend the lifespan of your equipment
Ensure a smooth, stress-free BWOF process
As one of New Zealand’s largest nationwide extraction-cleaning providers, National Hood & Duct Cleaning is here to help you stay compliant with no corners cut, ever.
If you need a full-system clean, IQP-ready reporting, or support with compliance schedules, book your next service with our team today.