In a recent blog post – Which way is up? – we highlighted contrasting opinions from planning inspectors about how the GPDO, in respect of Part 1 Class AA upward extensions, ought to be interpreted. The question is should it be only the effect on the building itself under consideration or can the effect on the street scene also be taken into account?
Another appeal decision (DCS Number 400-032-241) might represent a working solution for reconciling these differing interpretations of the GPDO. This appeal concerned a proposal, again under Part 1 Class AA, for an additional storey on a house in southwest London. In this case the inspector noted that the proposed materials and roof cover would correspond with the host dwelling. The fenestration pattern would also align with the existing fenestration. However, she found that whilst overall the architectural detailing would match that of the existing dwelling, the additional storey would significantly add to the height of the building. She observed that the resultant eaves and roofline would project obtrusively above that of the neighbouring houses.
Now here is the clever bit. The inspector reasoned that [our emphasis] ‘By adding an extra floor above, the development as proposed would fundamentally alter the architectural composition of the property within this street context and consequently would have a harmful effect on the external appearance of the dwellinghouse as a result of its inconsistency with the remainder of the terrace.’
The permitted development classes are set out at section 4.342 of DCP Online.