Permitted Development Rights London 2026: Complete Guide
Build your extension without planning permission. Everything you need to know about permitted development rights in London, including Article 4 directions by borough.
TL;DR - The Quick Answer
In London, permitted development rights allow rear extensions up to 4m deep on detached houses (8m with Prior Approval) and 3m on terraced or semi-detached (6m with Prior Approval), saving homeowners 2-4 months and £500-2,000 in planning fees. However, around 60% of London properties face restrictions from conservation areas or Article 4 directions, which remove standard PD rights. Rights are cumulative since 1948, so previous extensions reduce what remains. Extensions between 4-8m (detached) or 3-6m (terraced/semi) require Prior Approval (£96), while full planning permission costs £258-462 and takes 8-12 weeks.
What Are Permitted Development Rights?
Permitted development rights allow you to make certain changes to your home without needing planning permission. This can save you 2-4 months and £500-2,000 in planning fees. Mayfair Studio handles architectural drawings and building regulations approval for permitted development projects from £1,295 fixed fee. However, London has specific restrictions that make it more complex than the rest of the UK. Full details about permitted development rights are available on the Planning Portal.
Permitted Development Size Limits by Extension Type
| Extension Type | Detached | Semi/Terraced | Prior Approval |
|---|---|---|---|
| Single rear (depth) - standard PD | Up to 4m | Up to 3m | - |
| Single rear (depth) - with Prior Approval | Up to 8m | Up to 6m | Yes (42-day determination) |
| Single rear (height) | 4m max | 4m max | - |
| Two-storey rear | 3m max | 3m max | Not required |
| Side extension | Half width | Half width | If 7m rule |
| Loft conversion | 50m³ volume | 50m³ (semi) / 40m³ (terraced) | Not required |
| Conservation area | Restricted | Restricted | Required |
* All measurements from original rear wall. Conservation areas have significantly reduced permitted development rights.
| Extension Type | PD Limit | When Prior Approval Needed | Fee |
|---|---|---|---|
| Single rear (terraced/semi) | 3m depth, 4m height | If 3–6m depth | £96 |
| Single rear (detached) | 4m depth, 4m height | If 4–8m depth | £96 |
| Two-storey rear | 3m depth | Not required | £258–£462 |
| Side extension | Half house width, single storey | Not required (but may need planning) | £258–£462 |
| Loft conversion | 40m³ (terraced) / 50m³ (detached/semi) | Not required | £258–£462 |
| Conservation area | Significantly restricted | Full planning required | £258–£462 |
Source: Mayfair Studio analysis of GPDO and Planning Portal guidance • Data as of 2026
Single-Storey Rear Extensions
You can build under permitted development if your extension is:
Detached House
- Maximum 4m from rear wall (8m with Prior Approval)
- Maximum 4m height
- Maximum 3m to eaves
Terraced/Semi-Detached
- Maximum 3m from rear wall (6m with Prior Approval)
- Maximum 4m height
- Maximum 3m to eaves
Important: Extensions 3-4m or 6-8m deep require Prior Approval for neighbour notification.
Two-Storey Rear Extensions
Much more restrictive. You can build under permitted development only if:
- Maximum 3m from rear wall (all house types)
- No extension beyond the rear of the side wall
- First floor rear wall must be at least 7m from boundary
- Maximum 4m total height (not exceeding original ridge)
Side Extensions Under Permitted Development
Side extensions (including side returns) can be built under permitted development if:
- Maximum width: half the width of the original house
- Single storey only (maximum 4m height)
- Must be at least 7m from any boundary opposite the side
- No balconies, verandas, or raised platforms
Side return note: Most London terraced houses have side returns narrower than 7m from the boundary, which means they require planning permission in most cases.
Loft Conversions Under Permitted Development
You can convert your loft under permitted development if:
- Volume increase doesn't exceed 40m³ (terraced) or 50m³ (detached/semi)
- No extension beyond existing roof plane facing a highway
- Rear dormer must be at least 20cm from eaves and party walls
- Materials similar to existing house
- No verandas, balconies, or raised platforms
Dormer design options, costs, and what to do when your loft falls outside these limits are covered in our full loft conversion guide.
Article 4 Directions: The London Exception
This is where London gets complicated. Many London boroughs have Article 4 directions that remove permitted development rights in specific areas or for specific types of development.
Boroughs with Extensive Article 4 Directions
High Restriction Boroughs
- Westminster (most areas)
- Camden (conservation areas)
- Kensington & Chelsea (most areas)
- Islington (conservation areas)
- Hackney (many areas)
- Tower Hamlets (conservation areas)
- Greenwich (conservation areas)
- Richmond (conservation areas)
These boroughs often require planning permission even for standard rear extensions.
Conservation Areas and Listed Buildings
If your property is in a conservation area:
- NO side extensions under permitted development
- NO roof extensions (lofts/dormers) on rear or side
- Reduced permitted development rights for rear extensions
- Most external changes require planning permission
If your property is listed:
- Almost no permitted development rights
- Need both planning permission AND listed building consent
- Significantly longer approval process (4-6 months typical)
When You've Already Used Permitted Development Rights
Permitted development rights are cumulative since 1948. If a previous owner built an extension using permitted development rights, you may have less (or zero) permitted development rights remaining. This is why a professional check is essential.
Prior Approval vs Planning Permission
| Aspect | Prior Approval | Planning Permission |
|---|---|---|
| Timeline | 6 weeks | 8-12 weeks |
| Cost | £96 | £258-462 |
| Scope of review | Impact on neighbours only | Full design review |
| Neighbour consultation | Yes (adjacent only) | Yes (wider area) |
| Design changes | Limited | Can be required |
How to Check Your Permitted Development Rights
To definitively know if you can build under permitted development:
- 1Check if you're in a conservation area (your borough's planning portal)
- 2Check for Article 4 directions in your area
- 3Review any previous extensions (planning portal or survey)
- 4Measure your proposed extension carefully
- 5Use a free permitted development checker - Mayfair Studio's Property Intelligence tool checks conservation areas, Article 4 directions, and listed building status instantly for any London address
- 6Get professional assessment (recommended before investing in design)
Summary
Permitted development rights can save months and money if you qualify. However, London's Article 4 directions and conservation areas make it more complex than other UK regions.
Before you start design work, get a professional permitted development assessment. Our free checker can save thousands if you discover you need planning permission instead.
Permitted development allows homeowners in London to extend without planning permission within set limits: rear extensions up to 3m deep (terraced/semi) or 4m deep (detached), loft conversions up to 40m³ (terraced) or 50m³ (detached/semi). These rights are removed in conservation areas and Article 4 direction zones, which affect over 40% of London residential properties. Always check your specific address before assuming PD applies.
Frequently Asked Questions
What is permitted development for home extensions in London?
Permitted development (PD) allows homeowners to extend without planning permission within set limits. For rear extensions: max 3m deep for terraced/semi-detached, 4m deep for detached, max 4m high, single-storey only. For loft conversions: max 40m³ volume increase (terraced) or 50m³ (detached/semi). PD rights are removed in conservation areas, Article 4 direction zones, and for listed buildings - which affect large parts of inner London including Hackney, Islington, and Camden.
Can I build a rear extension without planning permission in London?
Yes - a single-storey rear extension up to 3m deep (terraced/semi-detached) or 4m deep (detached) typically qualifies as permitted development and needs no planning permission. The Prior Approval scheme allows up to 6m or 8m with neighbour notification. However, conservation areas, Article 4 directions, and listed buildings remove these rights. Check your specific postcode - Article 4 directions affect many inner London streets in Hackney, Islington, Camden, and others.
How do I check if my property is in a conservation area London?
You can check if your London property is in a conservation area three ways: (1) Use Mayfair Studio's free AI chat - enter your address and it instantly checks conservation area status, Article 4 directions, listed building status, and TPOs. (2) Search your local council's online planning map. (3) Check Historic England's National Heritage List at historicengland.org.uk. Conservation area status affects your permitted development rights and what materials you can use.
What is an Article 4 direction in London?
An Article 4 direction removes permitted development rights in a specific area, requiring planning permission for work that would otherwise be allowed without it. In London, Article 4 directions are common in Hackney (Stoke Newington, Dalston, De Beauvoir), Islington, Camden, and many other inner boroughs. They typically restrict rear extensions, loft conversions, side extensions, and changes to front elevations. Always check for Article 4 directions before assuming PD rights apply to your property.
Do I need planning permission for a home extension in London?
It depends on your property and location. Single-storey rear extensions under 3–4m deep, and loft conversions under 40–50m³, typically qualify as permitted development (no planning needed). However, in conservation areas, Article 4 direction zones, or for listed buildings, planning permission is required. Over 40% of London residential properties are affected by conservation area status or Article 4 directions. Mayfair Studio's free AI chat checks your specific address instantly.