Planning permission:we want to create a loft extension, do we need to consult a planning committee?

I'm desperate for more space in my south London Victorian terrace and have been blessed with a large loft. Do I need planning permission to create an extra attic bedroom and a balcony?

Question: I have just bought a mid-terrace Victorian house in south London and want to extend into the attic, with big windows for extra light in a new bedroom, and possibly even have a balcony. Will I need planning permission or can I just start building?

If your home is within a conservation area or if your property is listed, then you will need to apply for full planning permission. Loft conversions can be a prominent feature within a street and, therefore, there is more potential to cause harm to an area’s special character.

Your local council’s website should have maps showing where every conservation area is within your borough, while Historic England keeps a register of every listed building in the country on its website. Where there are no conservation issues, you can convert your loft space into an extra bedroom, study or even a man cave without the need for planning permission under what are called “permitted development rights” (The Town and Country Planning General Permitted Development Order 2015).



In the case of a terrace house, you may increase the cubic content of the original, unaltered roof space up to a total of 40 cubic metres, or up to 50 cubic metres in the case of a detached or semi-detached house. To ensure your new living space has enough light as well as headroom, you can build a rear dormer window. Box dormers are sometimes considered unattractive. However, it is the most space-efficient design and will make your new loft much more useable.

No part of your extension can project beyond the front roof slope, so if more light is essential, then I suggest installing a few flush Velux windows. 

Side windows and side dormers are allowed on the condition they contain obscure glazing and that windows are non-opening — or the part that opens is more than 1.7 metres from the new bedroom floor.

The materials you use in any exterior work must be of similar appearance to those used in the construction of your existing home. Unfortunately, balconies or raised platforms are not permitted development. This is because a veranda, balcony or raised platform has the potential to be overlooking and cause loss of privacy to neighbouring properties; therefore you would need to apply for full planning permission.

A word of caution, however. Before you spend £35,000-plus on a new loft, it is advisable to have your project design-certified as lawful (referred to as a Lawful Development Certificate — Proposed Use) by your local council.

Costing £97.50, a certificate of lawfulness would provide proof that your loft conversion is a permitted development. It is also useful to have this certificate if you think your neighbours are likely to complain, or if you want to sell your home in the future. You will need to submit a location plan at a scale of 1:1250 or 1:2500 showing your entire property outlined in red, along with existing and proposed floor plans, elevation sections and roof plan drawings at a scale of 1:50 or 1:100.

The application can be submitted online at

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