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How Far Can I Extend My House?


Many people want to add value to the property in one way or another. As interest rates begin to rise, many may think that moving is not a good idea. Instead, erecting an extension to the home is considered a better idea, not just for added value, but for comfort and space. But extending a property depends on a specific set of criteria.

Do I Need Planning Permission for an Extension?

In most cases, having an extension or addition to the house is classed as a “permitted development,” so it wouldn’t require planning permission. But if you are considering extending your property, the following components would require permission:

  • The size of the extension is more than half the area of land around the “original house”. 
  • The extension is taller than the tallest or highest part of the roof. 
  • If it is a single-storey rear extension, it extends beyond the rear wall of the house by more than three metres in a semi-detached house, or by four metres in a detached house.
  • The maximum height of a single-storey rear extension will be more than four metres.
  • If an extension of more than one storey extends beyond the rear wall of the house by over three metres. 
  • The maximum eaves and ridge height of the extension will be higher than the existing house.
  • If you want to use different materials, i.e. looks different in appearance to the existing house. 

How Far Can I Extend My House Without Planning Permission?

As permitted development rules have been relaxed, and as the “larger home extension scheme” has been made permanent, you can build an extension without planning permission up to six metres (or eight metres if your house is detached). But it is worth considering the following before extending the property:

The Type of Property

If you live in a flat, maisonette, or another type of building, you do not have permitted development rights. This means you cannot build an extension without full planning permission. And if your property has undergone a change of use or was converted into a house, permitted development rights may not be allowed.

Has the Property Been Extended After 1948?

Even if previous owners have extended the property, this can reduce your permitted development allowance.

Do You Have a Listed Property, or Is It on “Designated Land?”

If it is in a ‘protected’ area, such as a conservation area, national park, or areas of outstanding natural beauty, the permitted development rights might even have been removed. But even if the rights have been restricted rather than removed, this means you cannot build more than one storey, build a side extension, or clad the exterior.

While the above list is not exhaustive, you should always seek the guidance of a planning officer in your local authority. If you are looking to incorporate a modern house extension to add value to the property or you are looking for extra space, it is vital to consult the experts when reviewing if you need planning permission for an extension. Contact us and we can help with all the matters for you extension