Appeal against a refusal of planning permission for a rear mansard roof extension

Appeal Allowed (Full Planning Permission Granted) on 13 December 2022

lambeth roof extension appeal

69 Glencairn Road,
SW16 5DG

Council: London Borough of Lambeth

Lambeth Council in London is not at all keen on roof extensions.

It has quite strict planning guidance to limit the size and to control the design of dormer and mansard roof extensions.

We get a lot of roof extension enquiries from clients in Lambeth and we have noticed recently that we have been having quite a lot of success getting permission for roof extensions in the borough on appeal.

This is our latest success. Mr & Mrs Degioanni wanted to extend their flat at roof level by building an ‘L-shaped’ mansard extension, i.e. an extension over the main rear roof but also over the outrigger (the rear projection).

If they lived in a house, they could have built the extension using their permitted development rights. However, flats do not have the usual householder permitted development rights. This is something that is not well known and is, in our view, very unfair. We wrote about this ‘house v flats’ anomaly in an article on our blog.

At appeal, the inspector agreed with us that the mansards were well designed and would complement the character and proportions of the building. He acknowledged that the development differed from other extensions along the row – a point made by the council – but decided that this was not of great concern because the buildings were not protected (not in a conservation area, for example) and the development was to the rear and not visible from the street.

It is likely that Lambeth will continue to reluctant to grant permission for larger roof extensions to flats. However, these extensions make such a huge difference to flat-owners, sometimes almost doubling the size of their homes. If you are applying for permission and would like a supporting statement to support your application, or have already applied and been refused, contact our planning consultants for some advice. You can reach us on the form on our contact page or by emailing us directly on

Inspector’s appeal decision (mansard roof extension in Lambeth)

“Thank you so much for all your hard work and wisdom. We are truly grateful.”

Mr & Mrs Degioanni

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