Extension Planning Permission Back to Blog

Extension Planning Permission

Extension Planning Permission

Building an extension is one of the best ways to increase the value of your home. Whether you want to extend your home to accommodate a state-of-the-art kitchen or create more bedrooms, an extension is the most practical way to increase space.

In 2008, new regulations were passed which class house extensions as permitted developments, meaning you may build an extension onto your existing home without planning permission, except in the case of listed buildings and buildings within a conservation area.

Extension conditions and limits

If you live in a general residential area, you are free to extend your home without planning permission, but there are conditions and limits for doing so. These limits and conditions are fairly straight-forward:

  1. Your new extension must cover no more than half of the land surrounding your original home.
  2. Your new extension must not be higher than the highest part of the property’s original roof.
  3. Extensions built at the rear of a property with one storey have a maximum depth allowance of three metres for an attached property and four metres for a detached property.
  4. Extensions cannot exceed 4 metres high.

If you are likely to exceed any of these limits, you will need to apply for planning permission through your Local Planning Authority. There are other conditions and limits for building an extension and so we recommend that you visit The Planning Portal for more information.

Buildings in a conservation area

If you live in a house that’s in a designated or conservation area, you should consult with your Local Planning Authority prior to carrying out any work as you may need planning permission. This will depend on where your property is located.

Listed building extensions

Permitted development does not apply to listed buildings. Before you alter the structure or appearance of your listed home, you must consult with your Local Planning Authority. You will likely need listed building consent for your project to go forward, which is determined by your project’s development plans.
It is a criminal offence to extend your listed home without listed building consent.

For more information on extensions, please visit The Planning Portal.


The information contained within this article is strictly for guidance only.  Cost2Build recommends that you always check current sources of information in case regulations have changed. Cost2Build cannot accept any liability for miscommunication of the law in the case of a change in regulation or any action done to a property based on the information held in this article.

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