If you are looking for a way to maximize householder permitted development rights a recent appeal case in Kent (DCS Number 400-018-680) might be of interest. In this case an inspector granted a lawful development certificate for an underground games room and swimming pool, deciding that the works comprised permitted development.
The council’s reason for refusal was that the proposed works comprised an engineering operation and therefore did not benefit from permitted development rights. The inspector agreed that the works comprised an engineering operation, but reasoned that it did not follow that they did not benefit from permitted development rights. She pointed out that engineering operations are not specifically excluded from permitted development rights under the GPDO.
The inspector acknowledged that Class A of the GPDO does not expressly refer to underground alterations to dwellinghouses. Nevertheless, she considered that the enlargement, improvement or other alterations of a dwellinghouse for the purposes of the GPDO is reasonably capable of being interpreted as including an underground structure.
The council argued that as the underground structure did not sit directly below the dwellinghouse it was not a basement and therefore not within Class A. The inspector found nothing in the GPDO or the Technical Guidance that supports this argument. She agreed with the appellant that location directly below a building is not a prerequisite to the common sense and dictionary definition of basement as ‘a set of rooms below the surface of the ground’. With regard to Class A the inspector concluded that the works amounted to the enlargement, improvement or other alteration to the dwellinghouse, noting that there was no dispute that any of the conditions or limitations of Class A were not met.
Turning to consideration of the proposal under Class E of the GPDO, the inspector judged that in comparison to the dwellinghouse the footprint of the proposal was not excessive. She reasoned that a swimming pool by its very nature will occupy a sizeable area and found that the games room was not an excessively large space for its proposed use. Given the size of the planning unit she concluded that the size and scale of the proposed structure would not be disproportionate nor excessive for its stated purpose.
The inspector decided that, whether a development falling within Class A or Class E, or both, the council’s refusal to grant a certificate of lawful use or development in respect of a reinforced concrete structure with all works below ground level was not well founded.
Section 4.3421 of DCP Online is the place to find further information on GPDO Part 1 permitted development.