U4 waste exemption: burning waste as fuel in a small appliance

The U4 exemption allows you to use waste plant material or untreated wood as fuel in a small appliance to produce heat or power.

Types of activity you can carry out

These could include:

  • a plant nursery burning dead plants and untreated wood waste in a boiler to produce heat for its greenhouses
  • a business burning wooden pallets that have not been treated with timber preservatives in a boiler that also provides hot water for a building

Types of activity you cannot carry out

You cannot:

  • burn waste other than those in the waste codes listed
  • burn treated wood waste such as painted or stained pallets or door frames
  • use this exemption to burn waste for disposal – for example, you should not burn waste for heating when the outside temperature is comfortably warm
  • use this exemption to burn waste in the open – a brazier is not an appliance, it simply provides physical containment for what would otherwise be an open bonfire

Types of waste you can use

The waste codes are those listed in the List of Wastes regulations. You need to make sure your waste fits within the waste code and description in the table.

Waste code(s) Type of waste
02 01 03, 20 02 01 Plant tissue waste only
02 01 07, 17 02 01 Untreated wood only
02 03 04 Vegetable waste unsuitable for consumption or processing
03 01 01 Waste bark and cork
03 01 05 Untreated sawdust and wood shavings, other than those containing hazardous substances
03 03 10 Fibre rejects (fibrous vegetable waste from virgin pulp preparation or paper pulp production) only
15 01 03 Untreated wooden packaging only

Amount of waste you can use

You can:

  • burn less than 50kg of waste as fuel in 1 hour
  • store up to 10 tonnes of waste at any one time before using it


You must make sure:

  • the appliance (for example, a boiler) has a net rated thermal input of less than 0.4MW
  • the total net rated thermal input is less than 0.4MW, if there is more than one appliance (for example, four 0.1 MW appliances)
  • the waste is stored in a secure place
  • the waste you use is suitable for burning as fuel
  • you do not use any more waste than you need

Rather than using the waste as fuel, you can dispose of some types of waste by burning it in an incinerator under exemption D6: disposal by incineration.

The D6 exemption only applies at the place where the waste is produced.

Disposing of wood by burning should be a last resort. If suitable, wood should be recycled or recovered (including burning as a fuel) before disposal.

You may be able to spread the ashes from burning under these exemptions on agricultural land (U10) or non-agricultural land (U11).

Register a U4 exemption

You need to register this exemption with the Environment Agency if you meet the requirements:

You will need an environmental permit from either your local authority or the Environment Agency if:

  • your appliance or group of appliances have a net rated thermal input of more than 0.4MW
  • you wish to burn more than 50kg of waste over any 1 hour period
  • you want to burn any other type of waste not listed under this exemption
Published 28 April 2014
Last updated 18 January 2021 + show all updates
  1. Corrected typo in the table - the waste code for "Fibre rejects (fibrous vegetable waste from virgin pulp preparation or paper pulp production) only" is 03 03 10.

  2. Text amended for clarity: 'You can burn less than 50kg of waste as fuel in 1 hour.'

  3. Changed reference of 'dangerous substances' to 'hazardous substances' due to changes in the law.

  4. First published.