Amalgamating Flats in London: How Borough Policy Shapes What’s Possible
Category
Development Plans
Policy & Legislation
Region
London
Date
15 July 2025
London Borough planning policy generally focuses on protecting existing housing stock, maximising affordable housing and restricting ‘super-sized’ homes. In this article, we explore these often complex policies and look at solutions that satisfy local requirements.
Under Section 55 of the Town and Country Planning Act 1990, the amalgamation of two or more dwellings into a single home is not generally considered “development”, meaning that planning permission may not be required, especially for internal works in non-listed buildings. However, several London boroughs treat amalgamations as material changes of use and apply strict planning policies to manage or prevent them.
The Royal Borough of Kensington and Chelsea (RBKC) considers any amalgamation of units to be a material change of use and therefore requires planning permission. The adopted Local Plan (July 2024) contains a specific policy on this. Policy HO1 seeks to protect the number of existing marketing residential homes and not allowing the amalgamation of self-contained Class C3 dwellings. In practice, this means that proposals for amalgamation are currently refused outright.
Camden takes a more lenient view. The adopted Local Plan (2017) states under Policy H3 that a proposal resulting in the net loss of one dwelling is not considered a material change of use. As a result, many lawful development certificate applications for amalgamations have been successful to confirm the lawful use without the need for planning permission. The policy also allows exceptions where proposals would provide larger homes in areas lacking them or where existing units are sub-standard.
However, Camden’s emerging Local Plan Review proposes tightening this policy to protect existing housing and only allowing amalgamation under specific conditions.
Adoption of the Local Plan Review is expected in winter 2026.
In Westminster, the City Plan adopted in April 2021 includes Policy 8, which aims to protect housing stock and limit the creation of super-sized homes – defined as those over 200 square metres. Although the amalgamation of sub-standard units can be considered favourably, the size cap is strictly enforced. Applications exceeding this threshold are routinely refused.
Following the adoption of Wandsworth Local Plan in July 2023, restrictions on amalgamations have increased. Policy LP25 allows the amalgamation of no more than two non-family-sized dwellings to create one family-sized home. However, the combined unit must not exceed 130 square metres in floor area. This cap significantly influences proposals within the borough.
Lambeth previously adopted a strict stance relying upon Policy H3 in their 2021 Local Plan, resisting amalgamations unless exceptional circumstances could be demonstrated. However, a landmark High Court decision in 2024 has changed the landscape. The case involved a proposal to combine two flats, which was initially refused on the basis that it constituted a loss of housing stock. The Planning Inspector granted a lawful development certificate, concluding that no material change of use had occurred. Lambeth appealed to the High Court, but the judge upheld the inspector’s decision and dismissed all six grounds of appeal. The ruling confirmed that boroughs must set out specific prohibitions or limits on amalgamation of smaller units in their Local Plans, which it concluded that Policy H3 did not do. Furthermore, the London Plan does not, by itself, prevent the loss of a unit.
Islington’s Strategic and Development Management Policies (September 2023) includes Policy H2, which allows amalgamation provided planning permission is obtained. The policy states that housing must be replaced by at least the equivalent amount of floorspace and must not result in the net loss of more than one unit. What sets Islington apart is the policy’s explicit confirmation that amalgamation requires planning permission.
Southwark takes a relatively relaxed approach. Policy P3 of the Southwark Plan (adopted in February 2022) does not refer to unit numbers but instead focuses on maintaining housing floorspace. As such, amalgamations can often proceed without planning permission. In this situation a Certificate of Lawfulness can be secured if formal confirmation is required to demonstrate that no material change of use has occurred.
On the whole, planning policy across London boroughs is focused on protecting existing housing stock, maximising affordable housing and restricting ‘super-sized’ homes. As such individual boroughs define what is important to their strategy and make clear what they consider to be material considerations. The nuance of each policy needs to be recognised at an early stage, as it can have implications for the planning strategy for development proposals.
The Bell Cornwell team provides tailored advice to help you maximise your chances of success, from site selection and design coordination to planning applications and post-permission requirements. If you want expert planning support, get in touch with our team.
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Alex Yearsley is a Principal Planner based in Bell Cornwell’s London office. He joined the Bell Cornwell team in 2021 and since then he has been involved with a range of projects providing advice to both private and public organisations. He specialises in residential, educational and mixed-use development and Green Belt related projects.
