Insights, Planning Guide
Extending your home: planning permission or permitted development?
Not every extension needs planning permission, but knowing which route applies, and where the limits sit, saves time, cost and risk.
Extensions are the most common project we are asked about, and the first question is almost always the same: do I need planning permission? Sometimes you do, sometimes the work falls under residential permitted development, and getting that right at the start shapes the whole project.
What permitted development covers
Permitted development rights allow certain extensions and alterations without a full planning application, within defined limits on size, height, position and materials. Single-storey rear extensions, some side and two-storey extensions, and various roof and outbuilding works can qualify. The rules are detailed and the limits are precise, so a project that looks straightforward can still tip over into needing permission.
When you need planning permission
You will need a planning application where the work exceeds permitted development limits, where those rights have been removed, or where the property is a flat, a listed building, or in a designated area. Even when permitted development might apply, a Lawful Development Certificate is often worth obtaining to confirm it in writing and protect a future sale.
Where you are changes what you can do
Permitted development is more restricted in National Parks, National Landscapes, conservation areas and around listed buildings, exactly the sensitive settings we work in most. In these locations more work needs permission, and the design has to respond carefully to context. That constraint is not a barrier to a good result, it is the starting point for one.
Good design still pays off
Whether your extension needs permission or not, it is worth designing properly. A well-considered extension adds space that genuinely works, reads as part of the house rather than bolted on, and adds value. Our Flint Farmhouse extension in the South Downs is a good example of a sensitive addition to an existing home.
Common questions
Do I always need planning permission for an extension?
No. Many extensions fall under permitted development, but the limits are specific and are tighter in designated areas. A quick appraisal tells you which route applies to your project.
What is a Lawful Development Certificate?
It is a formal confirmation from the council that your proposed work is lawful under permitted development. It is not compulsory, but it gives certainty and is useful evidence when you come to sell.
Can I extend a listed building or a house in a conservation area?
Often yes, but it needs permission and, for listed buildings, listed building consent. The design has to be handled sensitively, which is where early, integrated advice matters most.
Planning an extension or renovation? Tell us about your house and what you would like to achieve, and we will set out the most realistic route.
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