Under the Government’s Permitted Development regulation, the majority of homeowners won’t need to gain planning permission from the local authority in order to alter or extend their loft space. Of course there are certain criteria that need to be met in order for your loft conversion to fall within Permitted Development. These include:

  • A volume allowance of 40 cubic meters for terraced houses;
  • A volume allowance of 50 cubic meters for detached and semi-detached houses;
  • No extension beyond the plane of the existing roof slope of the principal elevation that fronts the highway;
  • No extension to be higher than the highest part of the roof;
  • Materials to be similar in appearance to the existing house;
  • No verandas, balconies or raised platforms;
  • Side-facing windows to be obscure-glazed;
  • Any opening to be 1.7m above the floor;
  • Dormers are not permitted on a principal elevation that fronts a highway;
  • Roof extensions are not permitted in designated areas (including national parks, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites);
  • Roof extensions, apart from hip to gable extensions, to be set back as far as practicable at least 20cm from the eaves.

There are many benefits to working within the Permitted Development regulations. Unlike planning permission, it’s not subjective and doesn’t rely on a number of external factors such as neighbours, design and impact. Instead, it’s either within regulation or it isn’t – there are no grey areas.

At the initial consultation we’ll be able to tell you whether or not your home and intended loft conversion falls within the permitted development regulations or not. And for your peace of mind, before we lay a brick we’ll apply to the Local Authority on your behalf for a Certificate of Lawfulness for the proposed works.


If for any reason your home doesn’t fall within the permitted development regulations, it doesn’t necessarily mean that you won’t be able to alter or extend the building.

  • You require a small, medium or large dormer at the front of the property;
  • You would like to use materials which are different to those used on the existing building
  • You live within a designated area such as a national park, Areas of Outstanding Natural Beauty, conservation area or World Heritage Site
  • You would like to build beyond the plane of the existing roof slope that fronts the highway
  • You would like to build to a higher level than the existing roof
  • You would like to build a veranda, balcony or raised platform.

If your project is best described by any of the listed criteria, you will need to apply to your Local Authority for full planning permission. But don’t worry if this is the case.

As part of our service we’ll liaise with the Local Authority on your behalf. We’ve worked with planning departments all over the UK and are very familiar with the protocols.