An often unclear area of planning law (among the many others), the question of whether planning permission is required for the amalgamation of two or more dwellings into one has been made even more murky by the recent High Court judgment in The Queen on the Application of Royal Borough of Kensington and Chelsea v Secretary of State for Communities and Local Government, David Reis, Gianna Tong  EWHC 1785 (the 2016 Case).
Under the Town and Country Planning Act 1990 (the Act), planning permission is typically not required for internal works to a building. Thus, one would think that where a division of a dwelling into multiple units or an amalgamation of multiple units into one only involves internal works, the local authority planning department could be avoided. Unfortunately that assumption is wrong.
Section 55(3) of the Act stipulates that a division of one dwelling house into two or more dwelling houses requires planning permission; thus, the situation here is straightforward. Regrettably, the Act is silent on amalgamations.
The Act is clear that permission is required for “the making of any material change in the use of any buildings or other land” (s55(1)). Therefore, given that following an amalgamation the overall building will still be used for residential purposes, surely amalgamation is not a “material change of use”? Unfortunately, in both London Borough of Richmond v Secretary of State for the Environment, Transport and the Regions and Richmond upon Thames Churches Housing Trust  2 PLR 115, and more recently in the 2016 Case it has been concluded that amalgamation of dwellings can be a material change of use.
Determining what constitutes a “material change of use” requires an examination of the nature of the use, and the extent to which a particular use fulfils a legitimate planning purpose is a relevant fact in determination of whether a change is material. It is easy to see that division of a family home into two or more flats changes the character of the use and imposes more stress on the facilities required of the local area (i.e. increased parking). Can the same be said though if a building with four flats were to be altered into a single dwelling house?
The answer is yes, as amalgamations give rise to the loss of a housing unit which can have considerable impact on the housing stock available within an area and may be in breach of current planning policies.
Unhelpfully the situation remains unclear, since whether or not loss of housing stock will be a material change of use is dependent on the local planning policy. Even worse, notwithstanding that one might have regard for the local authority’s published planning policy, it may be that circumstances have arisen since the publication of the policy which were unforeseen when the policy was proposed/adopted thereby altering the local requirements.
The result? It appears to be a postcode lottery as to whether an amalgamation of dwellings will require planning permission. Given the impact of a finding that any amalgamation was done without the required permission, it would seem wise to err on the side of caution and either seek planning consent or an informal decision by the local authority, if you are thinking of amalgamating or seek guidance from the local authority, or alternatively an indemnity policy if you are purchasing a converted property.