U4: burning waste as fuel in a small appliance
Source: gov.uk (2025-07-01)

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

There’s a charge for most waste exemptions

This exemption is in band 2. Read waste exemption charges (https://www.gov.uk/government/publications/waste-exemptions-how-to-choose-register-and-pay/waste-exemption-charges) to find out what the charges and charging bands are.

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 (#waste-codes)
- 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.

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
Conditions

You must make sure:
- the appliance (for example, a boiler) has a net rated thermal input of less than 0.4 megawatts (MW)
- the total net rated thermal input is less than 0.4MW, if there is more than one appliance (for example, four 0.1MW 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
U4 related exemptions

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 (https://www.gov.uk/guidance/waste-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) (https://www.gov.uk/guidance/waste-exemption-u10-spreading-waste-to-benefit-agricultural-land) or non-agricultural land (U11) (https://www.gov.uk/guidance/waste-exemption-u11-spreading-waste-to-benefit-non-agricultural-land).

Register a U4 exemption

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

Register an exemption (https://www.gov.uk/guidance/register-your-waste-exemptions)

Related permits

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