In England, most grants of planning permission are deemed subject to a condition requiring a 10% biodiversity net gain, but GOV.UK guidance says householder development and development granted by permitted development rights are exempt, which covers a typical conservatory project.

What biodiversity net gain is

According to GOV.UK planning practice guidance, biodiversity net gain in England comes from Schedule 7A of the Town and Country Planning Act 1990, inserted by the Environment Act 2021. Subject to exceptions, every grant of planning permission is deemed to be subject to a condition that development delivers at least a 10% increase in biodiversity value relative to the pre-development value of the onsite habitat. The gain can be delivered onsite, through registered offsite gains or through statutory biodiversity credits, and before work starts a Biodiversity Gain Plan must be approved by the planning authority unless the development is exempt. The guidance says the framework applies to planning permissions granted for applications made on or after 12 February 2024. It relates to England; Wales, Scotland and Northern Ireland have separate approaches.

The householder exemption

The GOV.UK guidance, updated on 31 July 2026, lists householder development as a current exemption: development that is the subject of a householder application as defined in article 2(1) of the Town and Country Planning (Development Management Procedure) (England) Order 2015. A planning application for a conservatory or similar extension to a dwelling is normally a householder application, so the biodiversity gain condition does not apply to it.

Permitted development and other routes

The guidance also lists as exempt development granted planning permission by a development order under section 59 of the 1990 Act, which it says includes permitted development rights. A conservatory built under permitted development therefore does not attract the condition. It adds that retrospective planning permissions made under section 73A are outside biodiversity net gain, and that some section 73 permissions to vary conditions are also outside it.

Other exemptions

The de minimis exemption applies where development does not impact an onsite priority habitat and affects less than 25 square metres of onsite habitat and less than 5 metres of linear habitat such as a hedgerow. A further exemption for sites no larger than 0.2 hectares that do not impact an onsite priority habitat applies to applications made on or after 6 August 2026, as does an exemption for temporary development permitted for five years or less. Other exemptions cover urgent Crown development, biodiversity gain sites and development related to the high speed railway network.

The guidance gives an example of overlap: a side extension replacing a garage could be subject to the householder, 0.2 hectare and de minimis exemptions. In such cases the planning authority and applicant should focus on the most appropriate and easiest exemption to assess, and there is no need to evidence every one; for a development classified as householder, the focus should be on the householder exemption.

What this means for a conservatory project

For most homeowners the practical effect is that a conservatory does not need a Biodiversity Gain Plan. The exemption concerns biodiversity net gain only, and other rules such as protection for wildlife and trees apply separately and are covered in other guides on this site. Because the definitions depend on how the application is classified, the local planning authority can confirm the position for a specific proposal, particularly where the site includes a priority habitat.

The guidance explains that biodiversity net gain is intended to be a post-permission matter, so that the 10% objective is met after permission is granted through the Biodiversity Gain Plan, and that where a development is not exempt the applicant should consider it early, including using the authority’s pre-application advice service. It also says that biodiversity net gain will often be a material consideration when an application is decided, and that the authority has a role in monitoring and enforcing a plan once approved. Those steps are not required for an exempt householder conservatory, but they show why an application for a larger development on the same site, such as a new dwelling in the garden, could be treated quite differently.

The guidance separately notes that some routes to permission have not yet been brought into the framework, including local development orders, simplified planning zones and neighbourhood development orders. The GOV.UK page sets out the current list of exemptions and is updated periodically.

FAQs

Do I need a Biodiversity Gain Plan for a householder conservatory application?

No. GOV.UK lists householder development as exempt from the biodiversity gain condition.

Does permitted development trigger biodiversity net gain?

No. GOV.UK says development granted planning permission by a development order, including permitted development rights, is exempt.

Do these rules apply in Wales or Scotland?

The guidance describes England. Wales, Scotland and Northern Ireland have separate approaches that are not covered here.

Bottom line

Biodiversity net gain is a 10% requirement for most English planning permissions, but householder applications and permitted development, the usual routes for a conservatory, are exempt, alongside several other exemptions. Wildlife protection and other planning rules still apply separately. This is general information based on GOV.UK guidance; check the position with your local planning authority.

Sources

This guide draws on the following primary sources, current as of 20 September 2026:

• Ministry of Housing, Communities & Local Government via GOV.UK, “Biodiversity net gain” (planning practice guidance)

Related guides

Compare Conservatories is an independent guide. We may earn a fee from some links; this never affects what we write. This article is general information, not legal or planning advice on any specific property — always confirm requirements directly with your local planning authority.