Basement extensions and conversions can often be considered permitted development, not requiring an application for planning permission, provided they meet all the necessary criteria and there are no constraints that restrict or remove permitted development rights.
Converting an existing residential cellar or basement into a living space can in many cases be done without the need for full planning permission, as long as it is not a separate unit, does not change the use significantly, does not alter the external appearance of the property and there are no constraints.
Excavating to create a new basement or extend an existing basement involves major works, 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 are likely to fall within permitted development a lawful development certificate is recommended, so that you know your project is compliant and is protected from any retrospective planning issues, enforcements or penalties. 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.
If planning permission is required but the works are completed without first securing the proper planning approval you may face retrospective planning issues. If the local planning authority determine that planning permission was required an enforcement and or penalties may be issued. If planning permission cannot be secured retrospectively the basement may need to be put back to its original state.
If you are in any doubt our expert planning consultants can help. By carrying out a planning appraisal we can advise you on whether planning permission is required, the feasibility, process, timescales, likelihood of success and answer any other questions that you have. Once we know exactly what is required for your project, we will provide you an accurate quote for us to help you.