Appeal 3327584

The appeal is dismissed.

The appeal site is located within the Belgravia Conservation Area ‘CA’. The main issues in the appeal are whether the proposal would preserve or enhance the character or appearance of the CA and the effect of the proposal on the living conditions of the occupants of [address] with particular regard to outlook.

The appeal site is a dwelling house located on the corner of [address] and [address]. It has a main frontage to [address] and a wing at the rear which extends down [address]. Its main entrance is via steps up to a door on the [address] side of the main house.

No.[address] is its neighbour at the rear of the rear wing. No.[address] is its neighbour to the south-east and this is a terraced house which has a rear element and a small rear garden.

At the appeal site, there is a recent planning permission dated 29 August 2023 (application ref.23/00084/FULL) for the erection of a first floor rear extension and alterations to external elevations, replacement of single glazed windows with double glazed windows and alteration to front steps to create two secure bicycle spaces. The first floor rear extension would be located at the end of the appeal site’s small rear garden. It would be adjacent to [address] and would partly overlap the rear garden of no.[address].

The appeal site is identified in the draft Belgravia Conservation Area Audit as being an unlisted building of merit and so contributes to the character and appearance of the CA. In the vicinity of the appeal site the CA’s significance is found mainly in the general uniformity and pleasing architectural features of the terraced properties. The appeal property was probably originally built in the mid-1800s and rebuilt in the late twentieth century in modern materials with the addition of the [address] wing.

The proposed extension would be a mansard roof addition to the flat roof of the [address] wing. Its main roof line would be above the roof line of the main house and, where it would link into the main building, there would be a short section at a lower height creating the link. The extension would have a slate-clad roof with lead-clad dormer windows. There would be two windows facing [address] and two facing [address]. As [address] has two above ground storeys, the proposed mansard extension would have an exposed flank (end) upright wall adjacent to the roof of no.41.

Whilst there are mansard roof extensions close to the appeal site on [address], they are typically recessive in nature and located behind a parapet. The height of the proposed main roof of the proposal would be above the predominant height of the main house roof and the body of the mansard and the dormer windows would be highly exposed and visible. The main house forming the street corner is of a fairly simple design and the scale and mass of the resulting secondary wing would fail to be subordinate to the main building when viewed from [address]. Whilst the proposed link section would serve to create some separation, this would not adequately mitigate the resulting dominant and top-heavy appearance of the subsidiary wing.

There would be a loss of views of part of the undulating butterfly roof at the rear which can be appreciated from public and private vantage points and this adds to my concerns for preserving the CA. Similarly, the upright flank end of the proposed mansard extension next to [address] would be partially visible from the street and would appear discordant. 10.Consequently, the proposal would obscure an important architectural feature, and, owing to its particular siting, mass and design, would disrupt the uniformity and harmonious rhythm of buildings in the CA. 11.On this issue, therefore, I conclude that the proposed development would unduly harm the significance of the CA and would fail to preserve its character and appearance. It would be contrary to policies 38, 39 and 40 of the Westminster City Plan 2019-2040 (adopted April 2021) and the 'Roofs: A Guide to Alterations and Extensions on Domestic Buildings' Supplementary Planning Guidance of Westminster Council. Living Conditions of Occupants of [address] 12.The rear element of no.[address] has, amongst other things, patio doors out to the small rear garden with a window above at first floor level. There is one window in the flank (northwest) wall and this is at first floor level. The rear elevation of the main house has three windows in a vertical alignment which face the rear garden. When inside the house, the mansard would be visible but, in the main, from oblique views from those windows (the view from the flank wall window would be direct). Owing to the angle of view and distance between the windows and the proposed mansard, I do not consider that, when inside the house, the occupiers would experience a material loss of outlook as a result of the proposal. I come to the same conclusion when the cumulative effect with planning permission (ref. 23/00084/FULL) is taken into account. 13.However, when using the rear garden, with the first floor rear extension at no. [site address] built out (ref. 23/00084/FULL), the mansard proposal would combine with that extension to give a strong sense of being enclosed. Whilst the main roof of the mansard would slope inwards, the proposed dormers would be almost flush with the [address] wing wall. The overall effect of the proximity, height and mass of the proposal, combined with the built development permitted by application ref:23/00084/FULL, would cause an unacceptable increase in the sense of enclosure for the occupants of no.63 when using the garden. 14.On this issue, I conclude that the proposal would unduly harm the living conditions of the occupants of [address] by reason of loss of outlook. The proposed development would be in conflict with policies 7 and 38(C) of the Westminster City Plan 2019-2040 (adopted April 2021).