Blog 4: How to Get Planning Permission for a Rear Extension
How to Get Planning Permission for a Rear Extension — Step-by-Step UK Guide 2025
Planning a rear extension? First, find out whether you actually need planning permission — many rear extensions do not. But if yours falls outside Permitted Development rights, or you want the security of a formal approval, this guide walks you through every step of the planning permission process in the UK.
Step 1: Check Whether You Need Planning Permission
Before anything else, establish whether your rear extension qualifies as Permitted Development (PD). Under PD rights for Class A extensions:
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- A single-storey rear extension can extend up to 4m behind the original house for detached houses, and 3m for attached houses (terraces/semi-detached)
- Under the Prior Approval (Neighbour Consultation) Scheme, these limits extend to 8m (detached) and 6m (attached) — but you must notify the council and allow neighbours to object
- The extension must not exceed 4m in height at the eaves or 3m within 2m of a boundary
- No extension above the ground floor is allowed under PD
You need planning permission if:
- Your extension is two storeys
- You are in a conservation area, listed building, or flat
- The extension would exceed the PD size limits
- You want greater certainty than PD provides (a Lawful Development Certificate gives formal confirmation)
See also: Planning permission services by Crown Architecture
Step 2: Choose Your Design
Before submitting a planning application, you need a design. Work with an architect to produce:
- Existing drawings — plans and elevations of the property as it currently stands
- Proposed drawings — plans, elevations, and a site location plan showing the extension
- Design and Access Statement — a written explanation of the design rationale (required for most applications)
Good design matters for planning. Local authorities assess extensions against design quality, impact on neighbours, and compliance with local planning policies. A well-presented application with strong visual drawings is significantly more likely to succeed than a hasty submission.
Crown Architecture prepares full planning application packages for rear extensions across London and the South East.
Step 3: Submit Your Pre-Application Enquiry (Optional but Recommended)
Before submitting a formal application, many homeowners and their architects submit a pre-application enquiry to the local planning authority. This is a paid service (typically £100–£500 for a householder enquiry) that lets you get informal feedback from a planning officer before committing to a full application.
Benefits:
- Understand the council’s likely response before spending on full drawings
- Identify any specific policy concerns or requirements
- Get guidance on materials, massing, or design adjustments needed
Pre-application feedback is not binding, but it is often very useful — particularly for sensitive sites.
Step 4: Submit Your Householder Planning Application
A householder planning application for a rear extension is submitted through the Planning Portal (planningportal.co.uk) or directly to your local planning authority.
What You Need to Submit:
- Completed application form (online via the Planning Portal)
- Ownership certificate (confirming you own the property or have notified the owner)
- Site location plan (to a recognised scale showing the site in context)
- Block/site plan (showing the proposed extension footprint)
- Existing and proposed floor plans and elevations
- Design and Access Statement (for most householder applications)
- Application fee — currently £258 for a householder application in England (as of April 2024)
Application Fee Summary (England):
| Application Type | Fee (2025) |
|---|---|
| Householder extension (planning permission) | £258 |
| Prior approval for larger rear extension | £206 |
| Lawful Development Certificate | £129 (half the planning fee) |
| Pre-application enquiry | £100–£500 (varies by council) |
Step 5: The Consultation Period
Once your application is validated, the local planning authority notifies:
- Your immediate neighbours — they have 21 days to comment
- The local community / parish council in some cases
- Statutory consultees (e.g., Highways Authority, Environment Agency) if relevant
The planning officer considers all representations received. Neighbour objections do not automatically lead to refusal — but material planning concerns raised by neighbours are considered. Non-material concerns (e.g., “I will lose my view” or “this will devalue my property”) generally carry less weight.
Step 6: Await the Decision
The statutory determination period for a householder planning application is 8 weeks from validation. In practice, many applications are decided within this period — but complex or contentious applications may take longer, and you can agree to a time extension with the planning officer if needed.
The planning officer produces a report and issues one of three outcomes:
- Granted — Planning permission approved, often with conditions (e.g., materials must match the existing house)
- Refused — The application is declined. You receive a decision notice explaining the reasons
- Withdrawn — If it is clear the application will be refused, you may withdraw it to avoid a formal refusal on record
Step 7: If Approved — Next Steps
Once planning permission is granted:
- Note the conditions — Read all conditions attached to the permission carefully. Common conditions include: materials must match, no additional windows in side elevations, construction hours restricted
- Apply for Building Regulations — Planning permission and building regulations are separate processes. You must also get building regulations approval before building work commences
- Appoint a contractor — Get at least three competitive quotes based on a full specification
- Start work within 3 years — Planning permissions expire if development does not commence within 3 years of the decision date
Step 8: If Refused — What Are Your Options?
Do not despair. A planning refusal is not the end:
- Appeal to the Planning Inspectorate — You can appeal a refusal within 6 months of the decision. An independent inspector reviews the case. Appeals are free to submit
- Revise and resubmit — If the refusal identifies specific design or scale concerns, revise the scheme and resubmit. First resubmissions within 12 months of a refusal are free
- Pre-application discussions — Use the refusal reasons to guide a revised design before resubmitting
Crown Architecture has a strong success rate on planning appeals and resubmissions. We analyse refusal reasons carefully and advise on the best route forward.
Top Tips to Get Planning Permission Approved
- Work with an experienced local architect — Knowledge of your local planning authority’s preferences is invaluable
- Consult your neighbours early — An objection from a well-briefed neighbour is harder to deal with than one from a neighbour who knew nothing about your plans
- Match materials where possible — Matching brick, roof tiles, and window styles to the existing house is viewed favourably
- Keep scale proportionate — Extensions that overwhelm the host dwelling or overshadow neighbours attract more scrutiny
- Engage the planning officer informally — A brief conversation with the case officer before submission can surface issues early
How Crown Architecture Can Help
Crown Architecture handles the entire planning process for rear extensions across London and the Home Counties:
- Feasibility assessment and PD check
- Full planning drawings to a professional standard
- Planning application submission and management
- Correspondence with planning officers
- Appeal management if needed
Call or Text: 07443804841 to start your rear extension project.
FAQ: Planning Permission for Rear Extensions
Do I always need planning permission for a rear extension?
No — many rear extensions qualify for Permitted Development and do not require planning permission. However, conservation areas, listed buildings, larger extensions, and two-storey additions typically require a planning application.
How much does planning permission cost for a rear extension?
The planning application fee in England is £258 for a householder application. Additional costs include architect fees for drawings, and pre-application advice if desired.
How long does planning permission take for a rear extension?
The statutory determination period is 8 weeks from validation. Most straightforward applications are decided within this period.
Can neighbours stop my rear extension?
Neighbours can make material planning objections, but they cannot veto an application. Planning decisions are made by the local planning authority on planning grounds, not by a neighbour vote.
What happens if my planning application is refused?
You can appeal to the Planning Inspectorate (free to submit), revise and resubmit (first resubmission within 12 months is free), or pre-apply before submitting a revised scheme.
Do I need planning permission if my extension is under 4 metres?
A single-storey rear extension of up to 4m (detached) or 3m (terraced/semi) from the original rear wall generally qualifies as Permitted Development. Extensions between these limits and 8m/6m may qualify under the Prior Approval route.
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