Permitted development rules for single-storey rear extensions are not the same across the UK. England, Scotland, Wales, and Northern Ireland each have their own planning frameworks โ with different size limits, different conditions, and different exceptions. This guide gives you the exact rules for each nation in 2026, without the padding.
Even within each nation, PD rights can be removed by conservation area designations, Article 4 Directions, listed building status, or previous extensions using up your allowance. Always check with your Local Planning Authority before starting work. For England's full PD framework, see our companion guide: How Much Can You Extend a House UK? โ
Permitted Development (PD) is a national planning consent โ granted by Parliament, not your local council โ that allows certain types of building work to proceed without a formal planning application. It exists across all four UK nations, but each has its own rules and limits.
For homeowners, PD rights mean you can build within defined limits without applying to your Local Planning Authority (LPA). But this does not mean no rules apply. You still need:
PD does not replace planning permission โ it exempts you from needing it, subject to conditions. If your proposal falls outside PD limits for any reason, a standard planning application is required.
England's PD framework is set by the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended). For single-storey rear extensions, there are two routes: standard PD and the Larger Home Extension (Prior Approval) scheme.
| Property Type | Max Depth | Max Height | Eaves (within 2m of boundary) |
|---|---|---|---|
| Detached house | 4 metres | 4m (pitched) / 3m (flat) | Max 3m at eaves |
| Semi-detached house | 3 metres | 4m (pitched) / 3m (flat) | Max 3m at eaves |
| Terraced house | 3 metres | 4m (pitched) / 3m (flat) | Max 3m at eaves |
Additional conditions that always apply: The extension must not cover more than 50% of the original garden area (counting all outbuildings). It must not project beyond the front elevation. Materials must be similar in appearance to the existing house. No verandas, balconies, or raised platforms. The extension must be single storey only (max 4m ridge height).
For extensions deeper than the standard PD limits, the Larger Home Extension (Prior Approval) scheme allows you to go further โ but requires a notification to your LPA and a neighbour consultation.
The LPA can only assess impact on neighbouring amenity โ overlooking, light loss, and privacy. It is not a full planning assessment. This route does not apply in conservation areas, national parks, or where an Article 4 Direction is in force.
All depth limits in England are measured from the original rear wall of the house as first built, not from any existing extensions. If a previous owner added an extension, your new extension is still measured from the original wall โ which may mean you have little or no PD allowance left. Always check planning history before assuming your full allowance is available.
Scotland's permitted development framework is separate from England's and is governed by the Town and Country Planning (General Permitted Development) (Scotland) Amendment Order 2011 (as amended). The fundamental concept is the same โ certain works can proceed without planning permission โ but the specific limits differ.
| Rule | Limit |
|---|---|
| Max depth (all house types) | 3 metres from original rear wall |
| Max height | 4m (pitched roof) / 3m (flat or other roof) |
| Eaves height within 1m of boundary | Must not exceed 3m |
| Max total floorspace (all extensions) | Must not exceed 24mยฒ or 20% of original dwellinghouse floorspace (whichever is greater), up to a cap |
| Prior Approval / Larger Home Extension scheme | โ Does not exist in Scotland |
In Scotland, there is no equivalent to England's Prior Approval scheme. If you want to extend beyond 3 metres, you need a full planning application. Scotland also uses a cumulative floor area cap โ all extensions and ancillary buildings combined must not exceed the limit, so previous extensions count against your allowance.
Scotland's planning portal is ePlanning.scot. For Building Standards (the Scottish equivalent of Building Regulations), applications go to your local council's Building Standards department. Scotland also has its own Party Wall equivalent provisions under common law, though the formal Act does not apply in Scotland.
No distinction between detached and attached houses for PD depth โ all are limited to 3m. No Prior Approval route for larger extensions. Cumulative floorspace cap applies across all extensions. Building Standards rather than Building Regulations. Party Wall Act does not apply โ use a solicitor for boundary disputes.
Wales operates under its own legislative framework โ the Town and Country Planning (General Permitted Development) Order 1995 (as amended for Wales). Since 2016, planning policy in Wales has diverged further from England, and from April 2024, Wales introduced its own Prior Approval scheme for larger single-storey rear extensions, broadly equivalent to England's.
| Property Type | Standard PD Depth | With Prior Approval |
|---|---|---|
| Detached house | 4 metres | Up to 6 metres |
| Semi-detached or terraced | 3 metres | Up to 6 metres |
Note: Wales's Prior Approval scheme (introduced April 2024) allows extensions up to 6 metres for all house types โ it does not extend to 8m for detached houses as in England. The process is similar: LPA notification, 21-day neighbour consultation, 42-day decision window. The assessment criteria focus on neighbouring amenity.
Height conditions in Wales mirror England: maximum 4m ridge height for pitched roofs, 3m for flat roofs, and no more than 3m at the eaves where the extension is within 2m of a boundary. The 50% garden coverage rule also applies. Wales planning portal: planningportal.gov.wales.
In designated conservation areas in Wales, rear extensions that would be visible from a public road are generally not permitted development โ even within the depth limits. Wales has a number of National Parks (Snowdonia, Brecon Beacons, Pembrokeshire Coast) with additional restrictions. Always check with your LPA if your property is in or near any designated area.
Northern Ireland has its own entirely separate planning system, administered by the Department for Infrastructure (DfI) and local councils. Permitted development in Northern Ireland is governed by the Planning (General Permitted Development) Order (Northern Ireland) 2015.
| Rule | Limit |
|---|---|
| Max depth (rear extension) | 3.5 metres from the original rear wall of the dwelling |
| Max height | 4m (pitched roof) / 3m (flat roof or within 2m of boundary) |
| Max floorspace of extension | Must not exceed 15% of the original dwelling floor area, up to a maximum of 35mยฒ |
| Total cumulative extensions | Must not exceed 20% of original floor area or 40mยฒ (whichever is less) |
| Prior Approval / Larger Home Extension scheme | โ Does not exist in Northern Ireland |
Northern Ireland's rules are more restrictive than England's in one important way: the floorspace cap. An extension cannot exceed 15% of the original dwelling's floor area (capped at 35mยฒ). A small terrace may have very limited PD allowance as a result. This is not a factor in England or Wales, where only the depth and height limits and the 50% garden rule apply.
There is no equivalent to England's Prior Approval route in Northern Ireland. Extensions beyond 3.5m depth, or beyond the floor area cap, require a full planning application. Northern Ireland planning portal: planningni.gov.uk. Building Regulations are administered separately by the councils.
3.5m depth limit applies to all house types (no distinction between detached and attached). A floorspace cap applies โ 15% of original floor area, max 35mยฒ. No Prior Approval scheme. Party Wall Act applies in Northern Ireland but has not been as widely tested in courts as in England and Wales.
Across all four nations, there are circumstances where PD rights are removed or restricted regardless of the size of the proposed extension. These are not edge cases โ they affect a significant proportion of UK properties.
A Lawful Development Certificate (LDC) is a formal written confirmation from your LPA that your proposed works are lawful under PD โ or that an existing unauthorised extension has become lawful through the passage of time. It is not the same as planning permission. It is simply a legal document confirming you don't need it.
An LDC costs around ยฃ100โยฃ200 (approximately half the standard planning fee in England). Without one, you have no written proof that your extension is lawful. When you come to sell, your buyer's solicitor will ask about the planning status of any extension. An undocumented PD extension can delay a sale, reduce your selling price, or require indemnity insurance. The cost and hassle of obtaining an LDC retrospectively is always greater than doing it before you start.
In Scotland, the equivalent is a Certificate of Lawfulness of Proposed Use or Development, applied for through ePlanning.scot. In Northern Ireland, the process is similar โ apply to your local council's planning department. In all nations, the process involves submitting drawings and a description of the works, and the LPA has a set period to respond.
For full guidance on costs, planning rules, and what adds value to your property, see our companion guides:
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