Appeal 3310487

The appeal is dismissed.

The Council does not raise any objections to the proposed alterations to the ground floor elevation of the appeal property. The alterations would have regard to the existing elevation treatment, and I conclude that these alterations would enhance the character and appearance of the [address] Conservation Area (Conservation Area).

The main issue is whether the proposed roof extension would preserve or enhance the character or appearance of the Conservation Area.

The appeal property is in a corner location in an L-shaped mews. It comprises a two-storey stock brick dwellinghouse with a tiled dual pitched roof and raised side parapets, roof features which are somewhat unique in the mews. The buildings in the vicinity mostly have a mix of flat and mansard roofs and roof heights vary. There are some much taller buildings on the western and northern parts of [address] and on surrounding streets. The evidence indicates that the property is not original to the mews, but it has the traditional appearance of a mews house.

Having regard to the Conservation Area Audit for [address] 2008 (the Audit), the significance of the Conservation Area derives from its tight-knit network of terraced townhouses, most set in a regular grid street layout, and its built form which is of a consistent scale and generally occupies narrow plot widths. The Audit recognises that the mews buildings associated with the townhouses are significant and that these are characterised by their intimate scale, are generally two storeys in height and relate to the plot width of the principal building to which they are or were associated. In relation to [address], the Audit notes that it contains few original buildings and some unsympathetic rebuilds, with the east side being more complete.

The roofline of buildings in the mews is not uniform. However, due to their two-storey height, brickwork frontages, raised parapets and vertically proportioned windows, particularly on the upper floors, the frontages of the buildings on the east side, including the appeal property, have a consistent appearance that contributes to the Conservation Area.

The proposed front terrace cuts into the raised roof and would introduce a boxy, largely glazed, and horizontal feature not currently present in the mews and incompatible with the vertically proportioned windows. Further, the modern glazed balustrade would be a prominent feature of the roof extension design which would draw attention to the inappropriate glazed opening and detract from the detailing of the main elevation. The set back of the roof extension would be minimal and the glazing, together with the modern glazed balustrade, would be prominent features that would not be characteristic of the east side of the mews.

In addition, despite the backdrop of taller buildings, the introduction of a protruding flat rooflight would visually interrupt the roofline of the appeal property. In a highly prominent corner location, the proposed terrace and rooflight would be incongruous and discordant additions, that would contrast with the traditional mews appearance of the building and would be harmful to the character and appearance of the appeal property and the wider street scene.

Notwithstanding my concerns about the design detail of the roof extension, I have had regard to the examples of other mansard roof extensions in [address] and at [address]. I am satisfied that the proposed changes to the roof height and form and the rear dormer would not be prominent or incongruous features in the Conservation Area. This is due to the proximity of substantial buildings and limited access to the rear of the appeal site, and the general variation of the roofscape within the mews. Despite this, due to the design detail of the roof extension, the proposal would not preserve or enhance the character or appearance of the Conservation Area, although the harm would be less than substantial.

Paragraph 202 of the National Planning Policy Framework (the Framework) states that less than substantial harm to the significance of a designated heritage asset (in this case, the Conservation Area) should be weighed against the public benefits of the proposed development. The alterations to the ground floor would enhance the appearance of the Conservation Area due to the inclusion of a sash window and the reduction in the size of the garage door. The provision of larger and improved quality of accommodation is a private benefit. The public benefit of the ground floor alterations would not outweigh the great weight to be given to harm to the Conservation Area caused by the proposed roof extension. Therefore, I conclude that the proposed development would conflict with the Framework.

Overall, the proposal would be contrary to Policies 38, 39 and 40 of the City Plan 2019 – 2040 [name] 2021. These policies together seek to require all development to positively contribute to Westminster’s townscape and streetscape, to preserve or enhance the character and appearance of Westminster’s conservation areas, and for roof extensions to not impact adversely on heritage assets.

For the reasons given above, the proposal would conflict with the development plan as a whole and there are no material considerations, including the Framework, that would outweigh the conflict. Therefore, the appeal is dismissed.