Planning Appeal Win for a Basement Flat Extension in Lambeth

In 2017, I won an appeal against the London Borough of Lambeth, London for a basement extension to a ground floor flat—transforming a modest two-bedroom property into a spacious four-bedroom duplex.

The scheme involved excavating and extending the existing basement to create additional living accommodation.

The objective was to maximise the potential of the property within a constrained urban setting, delivering high-quality internal space without altering the overall footprint at street level.

In dense London boroughs like Lambeth, this type of development is often a practical way to increase living space while maintaining the character of the surrounding area.

The Planning Issue

The application had been refused by the London Borough of Lambeth, with concerns focused on the design, scale and massing of the extension, as well as the potential impact on neighbouring amenity.

At appeal, I took a detailed, evidence-led approach.

A key part of my strategy was analysing the site’s context—particularly the natural gradient, which reduced the perceived bulk of the basement works.

I also reviewed comparable developments in the immediate area, demonstrating that features such as light wells and similar extensions were already well established locally.

By addressing overlooking, scale and design concerns in a clear and structured way, I was able to show that the proposal would integrate successfully without causing harm to neighbouring properties.

Appeal Outcome

The Planning Inspector confirmed that the development was acceptable in both design and amenity terms.

Planning Appeal Advice

If you have a development project and you have received a planning refusal, contact me for practical advice on whether an appeal is the right option and how to proceed.

Andrew Ransome MRTPI Email: andrew@adpltd.co.uk | Tel: 01206 242070

About me

Andrew Ransome is the planning director at ADP and is a chartered member of the RTPI, with over 22 years of town planning experience.

Andrew has extensive experience offering strategic planning solutions to challenging projects in both rural and urban settings. Follow him on Linkedin.

Planning Appeal Successes

Planning Appeal Information