Do I need planning permission for a house extension?
In most cases, a single-storey rear extension may not need planning permission. Under England's permitted development rules, you can extend up to six metres from a detached house, or four metres from a semi-detached or terrace, without applying for planning. You still need building regulations approval regardless.
Two-storey extensions, side extensions wider than half the original house, and any extension on a listed building or in a conservation area almost always require a full planning application. Properties where permitted development rights have been removed by a planning condition will also need to apply.
When permitted development applies
- Single-storey rear extension within the size limits (6m detached, 4m semi/terrace)
- Extension does not exceed 4 metres in height
- Extension does not cover more than half the garden area
- Materials are similar in appearance to the existing house
- No part of the extension is forward of the principal elevation
When you will need planning permission
- Two-storey rear or side extensions
- Side extensions wider than half the original house
- Properties in conservation areas, National Parks, or AONBs
- Listed buildings (also need listed building consent)
- Flats and maisonettes (no permitted development rights for extensions)
- Properties where PD rights have been removed by condition
A pre-application enquiry with your local planning authority typically costs between 200 and 400 pounds and gives you informal feedback before you invest in full architectural drawings. You can also apply for a Lawful Development Certificate as written proof that your project may not need planning permission.
What this means for a quote
When quoting for an extension, it helps to state clearly whether the project falls under permitted development or requires a planning application. Itemising building regulations fees, structural calculations, and any party wall costs alongside the construction work gives the customer a complete picture. If you use TailoredQuote, you can generate an itemised scope of works that covers both the build and the regulatory costs in one document.
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