Planning Permission for a House Extension UK: Complete Guide [2026]
Written by Tom Ellis · Senior Trades Editor
Last updated: July 2026
Last updated: July 2026 · United Kingdom
Quick Answer
Last updated: July 2026 · United Kingdom
Most single-storey rear extensions fall under permitted development and do not need planning permission. However, you will need a householder planning application — costing £258 in England — if you exceed PD size limits, live in a designated area (conservation area, AONB, National Park), or own a listed building. Building regulations approval is always required separately, regardless of whether planning permission is needed.
Do You Need Planning Permission for a House Extension?
Many homeowners are surprised to learn that the majority of domestic extensions do not require planning permission at all. The General Permitted Development Order (GPDO) grants automatic consent for extensions that fall within certain size thresholds — known as permitted development (PD) rights. Whether your project needs a formal application depends on several factors.
You will need a householder planning application if any of the following apply:
- Your extension exceeds the permitted development size limits (e.g. a rear single-storey extension beyond 4 metres for a detached house or 3 metres for any other house, measured from the original rear wall).
- Your property is in a conservation area, Area of Outstanding Natural Beauty (AONB), National Park, or World Heritage Site — where PD rights are restricted or removed entirely.
- The property is a listed building. You will need both a full planning application and a separate Listed Building Consent (the latter is free but distinct). Any works affecting the character of a listed building without consent are a criminal offence.
- You are changing the use of an outbuilding or annex to a habitable, self-contained dwelling.
- Conditions on your title deeds remove permitted development rights — known as an Article 4 Direction or a planning condition imposed on a previous consent.
If you are unsure whether PD rights apply to your specific property, consult our permitted development rights guide or apply to your local planning authority for a Lawful Development Certificate— a formal written confirmation that your project does not require permission.
Planning Application Types and Fees
For most residential extensions, you will submit a householder planning application. This is a simplified process compared to a full planning application and covers works to a single dwelling house. The statutory fees are set nationally and paid when you submit.
| Application Type | England | Wales | Scotland |
|---|---|---|---|
| Householder application (extension) | £258 | £230 | £202 |
| Listed Building Consent | Free | Free | Free |
| Lawful Development Certificate | £129 (half householder fee) | £115 | Varies |
| Pre-application advice (council) | £100–£300 | £100–£250 | £100–£200 |
Beyond the statutory fee, you should budget for professional fees if you use an architect or planning consultant:
- Architect/planning consultant drawings and application: £1,000–£3,000 depending on complexity and location.
- Pre-application advice (written): £100–£300 from the council planning department. Strongly recommended for conservation areas, listed buildings, or contentious sites. Always request it in writing so you can rely on it.
- Structural engineer: £500–£1,500 if load-bearing calculations are required at design stage (more commonly needed for building regulations than planning).
How to Apply for Planning Permission: Step by Step
- 1
Check whether you need permission at all
Review the PD rules for your property type and zone. Check your title deeds for Article 4 Directions. If in any doubt, contact the council planning department or apply for a Lawful Development Certificate before commissioning drawings.
- 2
Seek pre-application advice (optional but recommended)
Submit a pre-application enquiry to your local planning authority for £100–£300. This gives you informal officer feedback before you spend money on detailed drawings. Always request the response in writing.
- 3
Commission an architect or planning consultant
Engage a suitably qualified professional to prepare a block plan (showing the site in context), floor plans, and elevations drawn to scale. For conservation areas or listed buildings, a Design and Access Statement will also be required, setting out the design rationale and how the proposal responds to its setting.
- 4
Submit the application via the Planning Portal
Most councils now accept applications through the national Planning Portal (planningportal.co.uk) or their own online systems. Pay the statutory fee at submission. You will receive a validation letter and application reference number within a few days.
- 5
Neighbour consultation and public comment period
Your council will notify adjoining neighbours and, in some cases, advertise the proposal on site. A minimum 21-day consultation period applies. Objections from neighbours are considered but are not a veto — the officer weighs them against planning policy.
- 6
Decision issued (8–13 weeks)
Standard householder applications are determined within eight weeks. If approved, you will receive a Decision Notice setting out any planning conditions (e.g. approved materials, no windows in side walls). Planning permission is typically valid for three years.
- 7
Obtain building regulations approval separately
Planning permission does not cover technical construction standards. Before work begins (or at commencement for a Building Notice), submit a separate building regulations application to the council's Building Control department or an Approved Inspector.
How Long Does Planning Permission Take?
The statutory determination target for a householder planning application is eight weeks from the date of validation. Major applications — generally those above ten dwellings — carry a thirteen-week target. In practice, council workloads and resourcing mean many applications take longer, particularly in London and the South East.
| Stage | Typical Timeframe |
|---|---|
| Pre-application advice | 2–6 weeks |
| Validation (after submission) | 3–10 working days |
| Neighbour consultation period | 21 days (statutory minimum) |
| Officer assessment and decision | 8 weeks (standard) / 13 weeks (major) |
| Appeal (if refused) | 4–6 months |
If your council misses the eight-week deadline without your agreement to extend time, you are entitled to appeal to the Planning Inspectorate on grounds of non-determination. However, waiting a little longer is usually preferable — an appeal locks both parties into a formal process with uncertain outcomes.
What Happens if Planning Permission Is Refused?
Nationally, approximately 87% of householder applications are approved. Common reasons for refusal include:
- Overdevelopment — the extension covers too much of the garden or is disproportionate to the host dwelling
- Adverse impact on neighbouring properties' light or outlook
- Design out of character with the surrounding area or the original building
- Loss of privacy through overlooking windows
- Impact on a heritage asset or its setting (conservation areas, listed buildings)
If refused, you have three main options:
Option 1: Revise and resubmit (recommended)
Address the stated reasons for refusal and resubmit. In England, one revised submission within 12 months of the refusal date is free of charge. This is the fastest and cheapest route if the issues are straightforward to resolve.
Option 2: Appeal to the Planning Inspectorate
Appeals are free and must be submitted within six months of the decision. The national success rate for householder appeals is around 35%, so this route is best reserved for cases where you strongly believe the council has made an error in applying policy. Expect a four-to-six month wait for a decision.
Option 3: Redesign to fit within permitted development
If the refusal reflects fundamental policy concerns, consider scaling the extension back to fit within PD limits. A smaller approved extension is far preferable to a refused — or worse, unauthorised — one.
Planning Permission vs Building Regulations: What Is the Difference?
These are two entirely separate legal systems and both are routinely required for a house extension. Confusion between them is one of the most common — and costly — mistakes homeowners make.
| Planning Permission | Building Regulations |
|---|---|
| Controls land use, design, scale, and impact | Controls construction standards and safety |
| Issued by local planning authority | Issued by Building Control (council or private) |
| Not always needed (PD rights may apply) | Almost always required for extensions |
| Valid for 3 years from grant | Inspection at key stages; completion certificate at end |
| Fee: £258 (England householder) | Fee: typically £400–£900 depending on size |
For building regulations, you can submit either a Building Notice (simpler, used for smaller jobs — work can begin 48 hours after submission) or a Full Plans application (larger or more complex jobs — drawings submitted and approved before work starts). The latter provides greater certainty and is advisable for significant structural works. A completion certificate is issued after the final inspection and is essential documentation for future property sales.
Common Mistakes and Key Pitfalls
- ✗
Assuming permitted development applies without checking
PD rights can be removed by Article 4 Directions, planning conditions on previous permissions, or your property's designation. Always confirm before starting work — unauthorised development can lead to an enforcement notice requiring demolition at your own expense.
- ✗
Starting work before planning permission is granted
Planning permission is only granted — not applied for. Commencing work without approval is a breach of planning control. Whilst there is a four-year enforcement window for completed extensions (ten years for change of use), unauthorised works can cause serious problems when selling the property.
- ✗
Ignoring building regulations because PD applies
Permitted development grants planning permission by default — it does not exempt you from building regulations. Every structural extension, however small, requires a separate building regulations application and inspections.
- ✗
Neglecting the party wall process
If your extension involves excavation near a neighbour's foundations, or work on or near a shared (party) wall, the Party Wall etc. Act 1996 imposes obligations to serve notice. This is separate from planning and building regulations and is easily overlooked. Read our party wall agreement guide for full details.
- ✗
Not reading planning conditions carefully
An approval is often subject to conditions — for example, specifying approved materials or restricting permitted development rights on the completed extension. Breaching a condition is a planning enforcement matter. Read your Decision Notice thoroughly and ensure your builder is aware of any conditions.
Frequently Asked Questions
When do I need planning permission for a house extension?
You need planning permission when your extension exceeds the permitted development (PD) size limits set out in the General Permitted Development Order. You will also need it if your property is in a conservation area, Area of Outstanding Natural Beauty (AONB), National Park, or World Heritage Site — where PD rights are restricted or removed entirely. Listed buildings require a full planning application plus separate Listed Building Consent regardless of size. Finally, some title deeds include conditions that remove permitted development rights entirely, so always check before starting work.
How much does a planning application cost in the UK?
The statutory fee for a householder planning application (the type used for most residential extensions) is £258 in England, £230 in Wales, and £202 in Scotland as of 2026. This covers the council's processing fee and is paid when you submit. On top of this, you will typically pay £1,000–£3,000 for an architect or planning consultant to prepare the required drawings and application documents. Pre-application advice from your local planning authority costs £100–£300 and is well worth the investment for complex sites.
How long does planning permission take?
The statutory determination period for a standard householder application is eight weeks from the date of validation. Major applications — generally those involving ten or more dwellings or large commercial floor areas — have a thirteen-week target. In practice, many councils exceed these targets, particularly in busy planning departments. If your authority misses the deadline and you have not agreed to an extension of time, you can appeal to the Planning Inspectorate on grounds of non-determination, though waiting a little longer is usually preferable to triggering an appeal.
What is the difference between planning permission and building regulations?
Planning permission is a legal consent that controls whether a development is appropriate in land-use terms — it considers design, scale, impact on neighbours, and the character of the area. Building regulations are a separate system that controls the technical standards of construction, covering structural integrity, fire safety, energy efficiency, drainage, and ventilation. You can build under permitted development (no planning permission needed) and still require building regulations approval. Conversely, receiving planning permission does not exempt you from building regulations. Both must be satisfied before — and during — construction.
What happens if planning permission is refused?
If your application is refused, you have several options. The most common route is to revise the scheme to address the stated reasons for refusal and resubmit — one revised resubmission within 12 months of the refusal is free of charge in England. Alternatively, you can appeal to the Planning Inspectorate within six months of the decision; appeals are free but typically take four to six months and have a national success rate of around 35%. A third option is to scale back the proposal to fit within permitted development limits so that no consent is required at all.
Do I need an architect to apply for planning permission?
There is no legal requirement to use an architect or any other professional when submitting a planning application — you can apply as a layperson. However, applications require accurate block plans, floor plans, and elevation drawings, which most homeowners are not equipped to produce to the required standard. A qualified architect or planning consultant will prepare these documents, advise on likely approval, and handle correspondence with the council. For straightforward extensions this typically costs £1,000–£3,000, which is a worthwhile investment given the cost of the extension itself and the risk of an avoidable refusal.
Related Guides
Need a Tradesperson for Your Extension?
Once planning permission is secured, find vetted local builders, architects, and structural engineers through Sleepless Tradesman — free to use for homeowners.
Find a Local Tradesperson