Do you need planning permission?

You may be wondering if you need planning permission to build or convert a basement and the good news is that basements can often be done under permitted development, which means you might not need planning permission!

However, in order to be permitted development they must meet all the necessary planning and design criteria. In addition to this there must be no constraints which limit or remove your permitted development rights.

If you are planning to convert an existing cellar or basement into a living space this can often be done without needing planning permission. This is providing it’s not a separate unit, doesn’t change the use significantly, does not alter the external appearance of the property and there are no constraints that remove your permitted development rights.

Building a new basement or extending an existing basement that will be a new separate unit of accommodation and/or alters the external appearance of the house, such as adding a light well, is likely to require planning permission.

For basement extensions and conversions that appear to meet the permitted development guidelines a lawful development certificate is recommended. This is the only way to get a legal determination that your project is permitted and protects you from any retrospective planning issues, enforcements or penalties.

Every application for a lawful development certificate will be assessed by the planning officer who will either approve or reject your application. If your application for a lawful development certificate is rejected then an application for full planning permission would be required.

Sometimes even if your project meets all of the permitted development criteria there can be hidden constraints that remove your permitted development rights. This would mean everything needs planning permission where another property doing the exact same thing could do it without

Building regulations may also be required depending on the extent of the works. If your basement shares a wall with another other property, you will likely require a party wall agreement.

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