Appeal 3364846

The appeal is dismissed.

I have determined the appeal on the basis of the Council’s description of the development proposed detailed on the decision notice, which I have used in the bullet header above, as it more accurately describes the development.

For the avoidance of doubt, I confirm that my determination of the appeal is based on the revised drawings submitted by the appellant on the 21 March 2025.

The main issue is the effect of the proposed development on the character and appearance of the host dwelling and the surrounding area, including whether it would preserve or enhance the character or appearance of The Chase Conservation Area (CA).

The appeal relates to a three-storey semi-detached dwelling with a lower ground floor. The dwelling retains traditional design features, including lower and upper ground floor canted bays with raised porches, shared Dutch gables and a two-storey projecting square bay at the rear elevation. Alongside the adjacent pair, 61 The Chase (No.61), the dwelling forms part of a cohesive group exhibiting similar architectural detailing and stucco decoration.

The appeal site is located in the CA. The terms of Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 (the Act), requires me to pay special attention to the desirability of preserving or enhancing the character or appearance of conservation areas.

The CA's significance derives from its historic street pattern and rich and varied architecture ranging from the 19th century onwards. Both main parties agree that the appeal property, which is located within the centre of the CA, makes a positive contribution to the special character and appearance of the CA.

During my site visit I observed the presence of a number of examples of rear extensions, of a variety of forms, and mansard roof extensions within the locality. However, the appeal property and its adjoining pair No. 61 retain largely unaltered rear elevations. This intact architectural composition and uniformity enhances their significance and contribution to the overall integrity of the CA.

The proposed rear extension would project approximately 2.5 to 2.8 metres from the original rear elevation and span the entire width of the property across the lower and upper ground floors with a staggered building line. As a result, it would obscure the existing rear two-storey bay, a characteristic feature of the host property, the semi-detached pair and others within the group. The proposal would therefore compromise the architectural balance and historic form of the building and would significantly disrupt the symmetry and legibility of the semi-detached pair.

Policies Q5, Q11 and Q22 of the Lambeth Local Plan (2021) (LLP) and the guidance contained within the [name] (2023) (the SPD) place significant emphasis on maintaining local distinctiveness, the subordination of extensions and the retention of original architectural features, particularly in conservation areas. The proposed full width rear extension fails to respond to these principles. It would not appear as a clearly subordinate intervention, rather it would dominate the host building at lower levels in terms of height, scale and massing. The use of matching material would not adequately address this harm.

Whilst the rear extension would not be visible in public views it would still be visible from private views from neighbouring windows and rear gardens where it would be seen as an overbearing, dominant feature, causing demonstrable harm to the character and appearance of the CA. The proposal therefore fails to preserve or enhance the character or appearance of the CA.

The appellant has referred to several comparable rear extension developments, including those at 65 and 67 The Chase. However, in the absence of detailed information regarding the planning context, circumstances, or rationale underpinning those developments, I attach limited weight to these examples. The rear elevations of properties at 18-28 The Chase, which have also been cited, are situated at a considerable distance from the appeal site and are of a distinctly different architectural typology. On the evidence presented, I therefore cannot be certain that they represent a direct parallel to the development. I have therefore determined this appeal on its own merits and find that the presence of other such developments does not justify further harm at this site.

While Policy Q11 of the LLP generally resists alterations to historic roof forms, the area contains a number of similar mansard roof extensions of varying age as well as a consented mansard at 57 The Chase. These examples now form part of the established roofscape and, where appropriately designed, complement their host buildings.

The proposed rear mansard roof extension would maintain the existing ridge height and incorporate traditional materials and detailing. Although it does not precisely align with the dimensional guidance for roof pitches set out in the SPD, such guidance is intended to be applied with due regard to the specific context. In this case, I consider that the scale, proportions, and traditional design of the mansard extension would represent a visually coherent addition that would respect the architectural character of the host building and given the existing variations between the roofs of the semi-detached pair, would not result in an unacceptable imbalance. On this basis, the proposed mansard roof extension would not appear incongruous, and would preserve the character and appearance of the host dwelling and CA.

The Council have raised no concern with the proposed front door, and, subject to detailed design being secured by safeguarding condition, the proposed front boundary treatment, rooflights, refuse store and fenestration. Based upon the evidence before me, and my observations on site, I concur.

While the proposed dormer and other works may preserve the character and appearance of the host dwelling and the CA, the proposed two storey rear extension would cause harm to the significance of the CA for the reasons set out above. Given the scale and location of the proposed development, the harm would be less than substantial in terms of the National Planning Policy Framework (2024) (the Framework).

In these circumstances Paragraph 215 of the Framework requires me to weigh the harm against the public benefits of the proposal. I have had regard to the public benefit associated with improvements to the quality of accommodation, which the appellant considers secures the optimum viable use of the appeal property, the reinstatement of traditional architectural features such as sash-style windows and improvements to the front boundary treatment which would have a limited positive impact upon the CA. I give these considerations moderate weight in favour of the appeal. However, I am not persuaded that these public benefits which are modest in scale and largely incidental to the two-storey rear extension, are sufficient to outweigh the harm identified and the great weight that should be given to the asset’s conservation.

I acknowledge that there is no published Conservation Area Appraisal or Management Plan for the CA. In the absence of such guidance, I have based my decision upon the evidence before me and my observations whilst visiting the site.

Overall, I conclude that the proposal would harm the character and appearance of the host dwelling and the surrounding area and would not preserve or enhance the character or appearance of the CA. As such, the proposal would conflict with Policies Q5, Q8, Q11 and Q22 of the LLP, which amongst other things, seek to safeguard, conserve and enhance the historic environment, and deliver high quality design that responds positively to local context. The proposal would also be contrary to the guidance contained within the SPD, which aims to create a high-quality, sustainable built environment.

The proposal does not accord with the development plan when considered as a whole and there are no material considerations, including the Framework, that indicate a decision should be made other than in accordance with it.

For the reasons given above, I conclude the appeal should be dismissed.