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Kitchen extraction systems

Kitchen extraction system

Norfolk Fire and Rescue Service is called to fires which start in the kitchen extraction systems and ducts of businesses like pubs, cafes, restaurants, and hotels.

  • Many of these fires are due to inadequate maintenance and cleaning.
  • You can reduce fire risks by carrying out regular cleaning of your kitchen extraction and ventilation systems.
  • Grease build up causes an environmental health hazard by providing a breeding ground for bacteria.

Fire risks

Filters cannot remove all traces of grease and dirt from the air. Over time a layer of grease and dirt builds up on the surfaces of the ventilation ducts, canopies and extractor fans. This presents a major fire risk.

Fires within the ductwork are very difficult to stop. Ductwork is often inaccessible, and fire may break out of the ductwork in other parts of the building. Damage is often serious and businesses are forced to close.

It takes six months to recover from a fire and many businesses do not reopen.

Cleaning and maintenance

  • Will reduce the risk of fire
  • It prevents the build-up of grease deposits and bacteria within your kitchen extraction system
  • Under the Regulatory Reform (fire safety) Order 2005 your extract systems need to be included in your fire risk assessment, with action taken to minimize any potential fire risk to buildings and occupants
  • Failure to carry out proper cleaning and maintenance could lead to a reach of environmental health regulations and could invalidate your fire insurance policy

Cleaning frequency

Ductwork Ideally you should measure the rate of build-up of grease on the internal surfaces of the ductwork. If this is not possible your cleaning work should be planned around the level of use:

  • Heavy use (12-16 hours per day) - clean every 3 months
  • Moderate use (6-12 hours per day) - clean every 6 months
  • Light use (2-6 hours per day) - clean every 12 months

Where cooking processes involve fat frying or wood/charcoal burning, cleaning may need to be more frequent.

Extract hoods and filters

These should be cleaned and degreased daily, or in accordance with the manufacturer's recommendations. Cooking should never be carried out without the filters in place.


Consult your building insurance company to ensure that your cleaning regime is compliant with any specific requirements they may impose regarding kitchen extract and ventilation systems.