A single storey rear extension is one of the most popular home improvements in the UK — and thanks to permitted development rights, many homeowners can build one without applying for full planning permission. But the rules are specific, and getting them wrong can cause costly problems further down the line.
This guide covers everything you need to know about single storey rear extension permitted development rules in England.
In most cases, yes. Single storey rear extensions fall under Class A of Schedule 2, Part 1 of the Town and Country Planning (General Permitted Development) (England) Order 2015. This means that as long as your extension meets the specified conditions, you don’t need to apply for planning permission.
There are two routes available to you depending on the size of your extension:
| House Type | Standard PD Depth | Maximum with Prior Approval |
|---|---|---|
| Detached house | 4 metres | 8 metres |
| Semi-detached or terraced | 3 metres | 6 metres |
Depth is always measured from the original rear wall of the property — not from any existing extensions or conservatories that may already have been added.
Size and height are not the only requirements. Your extension must also comply with all of the following:
If you want to build a rear extension larger than the standard PD limits (more than 3m for semi/terrace or 4m for detached), you can apply through the Neighbour Consultation Scheme, also known as the Prior Approval process.
Under this process:
This process typically takes around 42 days and allows extensions up to 6 metres deep (semi/terrace) or 8 metres deep (detached).
You will need to apply for full planning permission if:
Even though you don’t need planning permission for a PD extension, it is strongly advisable to apply for a Lawful Development Certificate (LDC) from your local council. An LDC formally confirms that your extension was lawful under PD rules — providing protection if you sell the property or if a neighbour disputes your right to build.
Even without planning permission, you will need full architectural drawings for building regulations approval and for your builder to work from. These include floor plans, elevations, sections, and structural details.
Our single storey rear extension drawing packages are fully compliant with UK building regulations and permitted development rules, available as instant downloads at a fixed price.
Under standard PD, 3 metres for semi-detached and terraced houses, 4 metres for detached. Under the Neighbour Consultation Scheme, up to 6 metres (semi/terrace) or 8 metres (detached).
Possibly, but any previous extension counts towards your PD allowance. The depth limit is measured from the original rear wall of the house, so a previous 2m extension would leave you with only 1m of remaining PD allowance for a semi-detached.
Yes. Permitted development only removes the need for planning permission. You will still need building regulations approval, which requires proper architectural drawings submitted to your local authority or an approved inspector.
You can build up to the boundary line, but if the extension is within 2 metres of the boundary, the maximum eaves height is limited to 3 metres. Always check your title deeds for any boundary agreements or easements.
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