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Basement Extension Engineering Works – Is Planning Consent Required?

Do the often noisy and dirty engineering works involved in creating basement extensions require planning permission in their own right? The High Court tackled that burning issue in blocking plans for a subterranean living space in Central London.

The property concerned was neither listed nor in a conservation area. The proposed extension was modest and would increase the property’s floor area by only 33 square metres. In the circumstances, the local authority took the view that planning permission was not required and issued the owner with a certificate of lawful development.

However, in upholding a local objector’s judicial review challenge to that decision and quashing the certificate, the Court found that the council had misdirected itself in law before concluding that the engineering works proposed were not a separate activity that required planning consent.

The council had asked itself the wrong question in finding that the engineering works were all part and parcel of the overall development, in that the latter necessarily required the former. In line with legal authority, it should have focused on whether the engineering works constituted a separate activity of substance.