Loft Conversion Planning

Over half of loft conversions do not require planning permission. If you are building a Velux or Dormer loft conversion in an area with no additional restrictions, you can usually build it as a permitted development. This means that you do not have to apply for planning consent or have your plans approved before starting the build. However, it does put limitations on the size, type, and scope of your loft conversion project so if you prefer to build a Mansard loft conversion (for example) you will need to go via the planning route.

Building Your Conversion as a Permitted Development

If you would like to build a permitted development, it’s essential that you check the history of your house and whether there have already been any additions. If you or the previous owners added a garage, house extension, or conservatory onto the house you may not be able to build a loft conversion as well since the allowable permitted developments have already been added.

If your house has not already had any additions, you will need to ensure that:

  • The additional space in the loft does not exceed 50 cubic metres for detached/semi-detached houses or 40 cubic metres for terraced houses
  • You use materials that match the rest of the house when building
  • The loft conversion isn’t built higher than the existing apex of the roof
  • There are no verandas, balconies, or raised platforms on the loft conversion
  • All of the side-facing windows are obscured
  • Any roof extensions are set back at least 20cm from the eaves

These restrictions are largely to allow people to make small changes to their homes without a significant impact on the look of the building or their neighbours’ privacy and available light. While many of our customers are happy to work within these requirements, some prefer to add a much larger loft conversion or create a balcony. If that is the case, we work with our architectural partners to guide you through the planning process to build the perfect loft conversion for you.

Gaining Planning Permission

If you’ve already had a permitted development built on your house or would like a larger loft conversion with some unusual features, you will need to gain planning permission to do so. It’s essential that this is gained before any building work is carried out – while some people have been successful in gaining retrospective planning permission, failure can mean having to return your home to its original state so it’s best to do this in advance.

Planning applications are submitted to your local authority, and there are slightly different conditions and requirements in every borough/area. Speak to us about your local requirements and we will put you in touch with your architectural partner who will help you through the process.


For more information or advice
Call 0800 0029 963