Apply for Accessory Dwelling Permission - London
In London, England, creating an accessory dwelling unit (annexe, granny flat or separate self-contained unit) typically requires planning permission or compliance with permitted development and building regulations. This guide explains when you must apply to your local planning authority, which permissions and building-control approvals are relevant, and the practical steps to submit applications. It is written for homeowners and landlords across London boroughs and reflects official guidance current as of February 2026.
Eligibility & When Permission Is Needed
Whether an accessory dwelling needs permission depends on: change of use, physical extensions, creation of a separate household, and conditions in the local plan. Many annexes that remain ancillary to the main house may fall under permitted development, but self-contained units often require full planning permission.
- Check if the proposal is a change of use to a separate dwelling (may trigger an application to the local planning authority).
- Extensions, new floors or significant alterations usually need building regulation approval and possibly planning permission.
- Listed buildings or conservation areas impose extra controls and specialist consents.
Use the national Planning Portal tool for guidance on annexes and permitted development tests to establish whether to apply for planning permission [1].
Penalties & Enforcement
Unauthorised annexes can trigger planning enforcement and building-control action. Enforcement options typically include enforcement notices, breach of condition notices, and prosecution for non-compliance; penalties and specific fine amounts are not specified on the cited pages. Local planning authorities and building control bodies are the enforcers; appeals, injunctions and prosecution are possible depending on the breach [2].
- Enforcement notices ordering removal or change of use.
- Court action or injunctions to require compliance.
- Fines and costs through prosecution where statutory offences are found (specific sums not specified on the cited page).
- Inspectors and local authority compliance teams investigate complaints and may serve notices.
Appeal and review routes: planning appeals are handled by the Planning Inspectorate; building regulation appeals and enforcement follow separate statutory routes. Exact appeal deadlines and fees vary by case and are set out on the relevant official pages and by the local authority; where a specific time limit is required it will be shown on the official appeal page or local decision notice.
Applications & Forms
Typical applications and approvals you may need:
- Planning application (householder or full planning) submitted to the local planning authority; use the Planning Portal to start most applications and to check local fee schedules.[1]
- Building Regulations application to either the local authority building control or an approved inspector; forms and guidance are available via the national building-regulations pages.
- Application fees are set by the local authority; consult the Planning Portal fee calculator or your borough’s planning pages for exact amounts.
Practical Steps and Compliance
Actionable steps to proceed legally:
- Check permitted development rights and whether the annexe is truly ancillary.
- Seek pre-application advice from your borough planning service to flag protected-area issues and likely conditions.
- Prepare and submit planning and building-control applications with plans, design & access statements, and any required heritage statements.
- Pay fees and monitor the application; respond promptly to consultee requests (environmental health, highways, conservation).
FAQ
- Do I always need planning permission to build an annexe in London?
- No—some annexes that remain ancillary may be permitted development, but self-contained units or works that affect the external appearance, change use, or are in conservation areas often require planning permission.
- What submissions are required for a planning application?
- Typical submissions include completed application forms, location and site plans, detailed drawings, a design and access statement where needed, and any heritage or ecological assessments if relevant.
- Can I get retrospective permission if I already built without consent?
- Yes—you can submit a retrospective planning application, but enforcement action remains possible and is at the local authority’s discretion.
How-To
- Check permitted development rules and whether the project is ancillary or a separate dwelling.
- Contact your local planning authority for pre-application advice and any local design guides.
- Prepare plans and documentation: site plan, floor plans, elevations, and supporting statements.
- Apply for planning permission (householder or full), using the Planning Portal if available, and submit required fees.[1]
- Apply for Building Regulations approval through local authority building control or an approved inspector.
- If refused, consider an appeal via the Planning Inspectorate and obtain legal or planning advice on grounds and time limits.[2]
Key Takeaways
- Accessory dwellings may require both planning permission and building-regulations approval.
- Pre-application advice from your borough reduces the risk of enforcement or refusals.
- Fees and penalties are set by authorities; check official pages and local decision notices for specifics.
Help and Support / Resources
- Find your local council planning department
- Greater London Authority - London Plan and planning guidance
- Planning Portal - apply for planning permission and guidance