Can separate planning units be merged to form one planning unit without obtaining planning permission?

Defining the planning unit

The courts use the concept of the planning unit to determine the area of land to be considered when identifying the primary use of land (and its ancillary uses), and whether any material change of use has occurred.

In addition, local planning authorities taking enforcement action against a breach of planning control need to determine the extent of the planning unit to establish whether there has been an un-authorised change of use.*

The question of whether sites are separate planning units would therefore be a question of fact and degree, based on the application of the above tests.

Merging separate planning units

The judgment in London Borough of Richmond Upon Thames v Secretary of State for the Environment, Transport and the Regions provides guidance on the merging of separate planning units.

The case concerned a house divided into seven flats, which was proposed to revert back to a single house. The court held that a material change of use had occurred. The judge considered that part of the assessment of materiality was effect on planning policy, which here was against the loss of small residential units.

Unfortunately the judgement did not go on to the Court of Appeal and there do not appear to have been any further developments on this point since, either in the courts or at appeal.

The current position therefore is that the question of whether planning permission is needed to merge planning units depends on the relevant local and national planning policy in the area.

Immunity from enforcement

Where uses have already ‘merged’, it may also be worth considering whether the merged uses could now be immune from enforcement action.

Where there has been a breach of planning control consisting in the carrying out without planning permission of building, engineering, mining, or other operations in, on, over or under land, no enforcement action may be taken after the end of the period of four years beginning with the date on which the operations were substantially completed.

In the case of any other breach of planning control, no enforcement action may be taken after the end of the period of ten years beginning with the date of the breach.

*LexisPSL Property subscribers can find further information in our Practice Note: Defining the planning unit which explains the tests to distinguish between separate planning units, including identifying the unit of occupation, sole primary use, geographical separation, composite uses, similarity of purposes of the sites and any ancillary uses. The note provides links to cases which have applied these tests.

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