Loft Conversion Planning Permission

Planning permission in London is determined by each of the 33 London Boroughs rather than a centralised authority. If you require planning permission, you will need to submit designs to your local authority for their consideration – however, you may be able to complete your loft conversion as a permitted development without needing to go through the full process to gain planning consent.

Permitted Developments in London

Many loft conversions in London can be carried out as permitted developments. This is most often the case with Velux and Dormer loft conversions, which do not involve extensive changes to the exterior of your home. However, if your plans include a Mansard loft conversion, it is likely that you will need to apply for planning permission.

Permitted developments have far more limitations than works that require planning permission, but they are often completed quickly as they do not involve extensive changes to the building and the initial wait is reduced. If you would like to design your loft conversion to be built as a permitted development, please let our team know and we will ensure that your build is planned around these restrictions. It is important to remember that permitted developments can’t be carried out on homes that have already had the maximum number of permitted developments completed.

The limitations are:

  • Your loft conversion must have a maximum volume of 50 cubic meters (or 40 cubic meters if you live in a terraced house).
  • Your loft conversion may not extend beyond the plane of the existing roof slope.
  • You may not extend your roof beyond the highest part of the existing structure.
  • Materials used for your loft conversion must blend in with the rest of your home (ie. you may not drastically change the exterior of your home).
  • Your loft conversion may not include a veranda, balcony, or raised platform. If you would like a Juliette balcony, please discuss this with your architect to find out whether this is allowed in your local area.
  • Any roof enlargements may not overhang the face of the wall of the original house, and any extensions must be set back from the original eaves by at least 20cm.
  • All side-facing windows must be obscured.
  • Roof extensions may not be allowed in conservation areas.

Planning Application

Our architect partners will manage the planning process for you, from submission of designs to notifications and alterations (if necessary). Once we have submitted the application on your behalf, you have the option of tracking it online but we provide regular updates throughout the process to keep you informed.

Working through an experienced architect rather than submitting the application yourself ensures that there are no delays at the validation process and you have a better chance of approval as our team has extensive experience in the area.

ANY QUESTIONS? CALL 020 3174 1241
Case Studies

Loft Conversions Add a Fifth to Property Values

Loft conversions are one of the best ways to make your home more spacious – an intelligently-designed conversion can add as much as 30% more living space to your home without extending the footprint of your house. As with all home improvements, conversions also increase the value and sale-ability of your home. A study by […]

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The client wanted to make extensive improvements to her home in Wandsworth, including a loft conversion, a kitchen extension, and alterations to her existing lounge and one of the existing bedrooms. All of the work took around 12 weeks and they were extremely happy with the results.  


Avian Construction Ltd

Peterden House
1A Leighton Rd
West Ealing
W13 9EL

020 3174 1241