Appeal 3350580

The appeal is allowed and planning permission is granted for erection of a mansard roof extension at [site address] in accordance with the terms of the application, Ref 24/01942/FULL, subject to the following conditions:

The development hereby permitted shall begin not later than 3 years from the date of this decision.

The development hereby permitted shall be carried out in accordance with drawing nos: MR-750-P-002, MR-750-P-003, MR-750-P-004, MR-750-P-005, MR-750-P-006, MR-750-P-007, MR-750-P-008, MR-750-P-101, MR-750-P-102, MR-750-P-103, MR-750-P-104, MR-750-P-105, MR-750-P-106, MR-750-P-108 and Site Location Plan planning portal reference PP-12705698v1.

The extension hereby permitted shall not be occupied until the window in the side elevation of the mansard roof as shown on the approved drawings has been fitted with obscured glazing, and no part of that window that is less than 1.7 metres above the floor of the room in which it is installed shall be capable of being opened. Details of the type of obscured glazing shall be submitted to and approved in writing by the local planning authority before the window is installed and once installed the obscured glazing shall be retained thereafter.

Since this appeal was lodged an appeal decision has been issued that relates to the neighbouring properties, [address] (appeal reference number APP/X5990/W/24/3344532). The decision allows the construction of a mansard roof extension across both properties. The Council and the appellant have been invited to submit comments on this decision and I have had regard to their submissions. While noting the Inspector’s comments on this previous appeal decision, I have assessed this current appeal on its own merits having regard to its particular effects and the parties’ submissions.

The main issues are the effect of the development on the character and appearance of the host property as a non-designated heritage asset and whether the proposal would preserve or enhance the character or appearance of the Westbourne Conservation Area (the CA). In carrying out my assessment, I have paid special attention to the desirability of preserving or enhancing the character and appearance of the CA.

The appeal property (No 10) lies within a largely residential urban street. Also, it is in the CA, which includes several other local roads that tend to be residential in nature. The CA gains its significance from the historic, architectural and aesthetic interest of many of the period properties that were constructed in a short period of time starting in the 1840’s. The buildings tend to be either semi-detached villas or terrace housing. Most display fine Italianate detailing.

The appeal property is an 1840’s villa that is of a design typical of the CA. The Council’s Westbourne Conservation Area Audit 2002 (the Audit) states that virtually all of the unlisted buildings within the CA are deemed as being buildings of merit. The appeal property has historic and architectural interest due to its age and characteristic style. Therefore, it is a non-designated heritage asset that makes a positive contribution to the CA as a whole.

No 10 lies at the end of a short row of similar villas that form pairs of semi-detached houses, including 6 and [address] (Nos 6 and 8) and 2 and [address] (Nos 2 and 4). The appeal property was also originally constructed as one half of a similar pair of houses. However, the attached property has been demolished and replaced with a row of 4 storey high buildings. As such, there is a significant and stark difference between the height and design of the appeal property and the attached terrace. Also, there are [address] properties on the opposite side of the street. Unlike other parts of the CA where there is a consistency of building styles, there is a mix of properties on this fairly short stretch of [address].

It is proposed to replace No 10’s hipped roof with an additional storey contained within a mansard roof. This change would be visible from the street directly in front and from further along [address] in either direction. As such, the development would have a noticeable effect on the character and appearance of the appeal property as well as on the street scene.

The Audit states that the architectural integrity of the semi-detached villas hinges on the distinctive hipped roofs with overhanging eaves. As such, it generally advises against roof extensions within the CA. In these regards, the proposal would go against the provisions of the Audit. Even so, the Audit does not form part of the adopted development plan and it is necessary to consider the proposal having regard to its specific context and its effects.

The appeal property has already been altered significantly since it was constructed, most notably as it no longer forms part of a uniformed pair of dwellings. Also, it would seem that No 10’s roof was altered at the time of the demolition of the attached property. Therefore, its current hipped form is not the same as when constructed. As such, the existing roof does not meaningfully contribute to the historic interest or architectural integrity of the building. Consequently, there is no sound justification to resist changes to No 10’s roof simply on the basis of preserving its significance.

The proposed extension would retain the overhanging eaves and the front window would align with the existing window at first floor level. The development would not affect the existing stucco and detailing on the vertical elevations of the building. Its proportions and design would respect the property’s architecture and scale. Therefore, the proposal would respect and would not harm the architectural and historic interest of No 10.

Furthermore, Nos 2 and 4 already have mansard roofs, whereas planning permission exists for similar roofs for Nos 6 and 8. Even if this recent planning permission is not implemented, it is noted that Nos 6 and 8 already have been extended at roof level. As such, there is no consistency in local building heights and roof forms, particularly when considering the taller terraces that adjoin and lie opposite No 10. Within this context, the development would not appear unusual and it would not disrupt an obvious uniformity.

The Council suggests that the mansard roofs at Nos 2 and 4 should not be used to justify the appeal scheme as they are top-heavy and incongruous additions. However, I find these mansard roofs reflect the style and period of the street and the wider CA. I take support for my view on this issue from the Council’s document entitled Roofs - A Guide to Alterations and Extensions on [name], which states that mansard roofs are appropriate for many 18th and 19th century houses1. The Council’s Supplementary Planning Guidance – Development and Demolition in Conservation Areas also states that in many parts of Westminster City mansard roof extensions are most appropriate, although not a universal solution2. Accordingly, I consider the proposed mansard would be suitable and sympathetic to the CA.

For these reasons, I conclude the development would not harm the character and appearance of the host property as a non-designated heritage asset and that it would preserve or enhance the character or appearance of the CA. In these regards, the proposal would accord with policies 38, 39 and 40 of the [site address] City Plan 2021.

Concern has been raised over the front window of the proposed development leading to overlooking into front windows of properties on the other side of the road. The mansard roof front window would provide similar views of the buildings opposite to the windows at second floor level and above in the adjoining terrace. Also, there would be a significant separation between the front of the mansard and the opposite buildings due to the intervening highway. Therefore, the development would avoid an unacceptable intrusion of privacy. This concern does not justify the refusal of planning permission and so it does not affect my overall conclusion. 1 [name] to Alterations and Extensions on [name], section 5 under sub heading “The Mansard Roof”. 2 Supplementary Planning Guidance Development and Demolition in Conservation Areas, paragraphs J.2 and J.3.

I have had regard to the planning conditions as suggested by the Council in light of the advice on conditions as set out in the National Planning Policy Framework. In the interests of clarity, I attach a condition that requires the development to be carried out in accordance with the approved drawings. As these include details of external materials to be used in the construction of the extension, there is no need for a separate condition specifically on this matter. To prevent unacceptable overlooking and loss of privacy to No 8, I include a condition that requires the side window in the proposed mansard to be obscure glazed.

For the reasons given above, I conclude the proposal would accord with the development plan when read as a whole. Therefore, the appeal should be allowed.