Biodiversity net gain: exempt developments
A guide to the types of development that will be exempt from the mandatory biodiversity net gain (BNG) requirements.
Applies to England
This draft guidance explains what will apply when BNG becomes mandatory. The guidance will continue to be updated.
The developments listed in this guide are exempt from BNG rules.
Small developmentssites (exempt until April 2024)
SmallA developmentssmall aresite defineddoes asnot ‘notfall into the category of a major developments’development, underas defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
A small developmentsite means:
- residential development where the number of dwellings is between 1 and 9, or if this is unknown, the site area is less than 0.5 hectares
- commercial development where floor space created is less than 1,000 square metres or total site area is less than 1 hectare
- development that is not the winning and working of minerals or the use of land for mineral-working deposits
- development that is not waste development
Developments below the threshold
A development that’s below the threshold means that it does not impact a priority habitat and impacts less than:
- 25 square metres (5m by 5m) of habitat
- 5 metres of linear habitats such as hedgerows
Householder applications
These are applications made by householders as defined within article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
It includes, for example, small projects like home extensions, conservatories or loft conversions
Self-build and custom build applications
An exemption applies to this type of development when all the following conditions apply:
- it consists of no more than 9 dwellings
- it’s on a site that has an area no larger than 0.5 hectares
- it consists exclusively of dwellings that are self-build or custom housebuilding as defined in section 1(A1) of the Self-build and Custom Housebuilding Act 2015
Biodiversity gain site
Developments undertaken for the purpose of fulfilling the BNG planning condition for another development are exempt.
High speed rail transport network
An exemption applies to any development forming part of, or ancillary to, the high-speed railway transport network, comprising connections between all or any of the places or parts of the transport network specified in section 1(2) of the High Speed Rail (Preparation) Act 2013
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Last updated 14 December 2023 + show all updates
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Updated to clarify that a small site does not fall into the category of a major development, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
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First published.
Update history
2024-08-21 11:05
Updated to add clarity about what criteria a development must meet to qualify for exemption as a self-build or custom build. A link has been added to guidance on self-build and custom housebuilding.
2024-04-02 09:00
Removed ‘small developments’ from the exemptions list as small developments are subject to BNG from 2 April 2024.
2024-02-12 12:28
Updated box at top of page to state that biodiversity net gain (BNG) is mandatory from 12 February 2024 and removed the ‘draft guidance’ label. Also provided more clarity around the ‘Developments below the threshold’ exemption. Added other exemptions.
2023-12-14 13:40
Updated to clarify that a small site does not fall into the category of a major development, as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015.
2023-11-29 14:27
First published.