You can’t tell by looking

An inspector has granted prior approval for two additional floors on a block of flats in west London after her inspection from the roof of the building revealed that it was detached from its neighbour, in line with GPDO requirements (DCS Number 400-031-420).

Class AA of Part 20, Schedule 2 of the GPDO, the inspector noted, permits construction of up to two additional storeys of new dwelling houses immediately above the topmost storey on a detached building. For the purposes of the GPDO “detached” means that the building does not share a party wall with a neighbouring building.

There is no definition of what constitutes a party wall within the GPDO, the inspector recorded, but the Planning Portal defines a wall as a “party wall” if it stands astride the boundary of land belonging to two or more different owners. A further interpretation is provided which states that the party wall is the dividing wall or partition between two properties which is shared by the owners or tenants of each side. 

The inspector observed that the front elevations of the neighbouring building and the appeal building were seen to adjoin one another and this was also the case at the rear when viewed from the service yard. However, the appellant confirmed that this was minor infilling of the gaps at the front and rear, the purpose being to prevent litter collecting in the narrow space that separated the two buildings.

During her site visit, the inspector related, she was able to observe the gap between the two buildings clearly from elevated vantage points, and decided that the minor bonding between them would not fall under the definition of a party wall. In determining whether or not a building is detached for the purposes of Class AA, she remarked, this should not be limited to a visual inspection from public land alone, concluding that it had been sufficiently demonstrated that the appeal building was detached for the purposes of the Class.

Local planning authorities might be relieved to hear that the inspector nonetheless declined to award costs against the council, reasoning that, given that the gap between the buildings was not evident from public vantage points, it would have been reasonable for the council to expect this essential information to accompany the application in order for it to assess whether the building complied with Class AA.

The permitted development classes are set out at section 4.342 of DCP Online.