Appeal 3310826

The appeal is dismissed.

The description of development in the banner heading above is taken from the planning application form. On the appeal form, the appellant indicates that the description used on the application form is still correct. However, their appeal statement gives the development description as ‘Erection of a single storey ground floor infill extension and the erection of a mansard roof extension. Removal of a rear lower ground door for the installation of a window; and replacement front UPVC window with sash windows and the installation of a rooflight over the outrigger; installation of a rear upper ground floor window and replacement front PVC downpipe for aluminium downpipe. Excavation of the rear garden for the formation of a terrace with external steps.’ This more fully and accurately describes the development proposed than the application form description, and is consistent with the description stated on the Council’s decision notice. I have therefore considered the appeal on that basis.

The 1:1250 scale Location Plan on drawing no (00)_099 Rev 01 includes a section of land beyond the rear of the gardens of the appeal and adjacent dwellings. This section of land is not shown as within the red line on the 1:200 scale Block Plan on the same drawing, the location inset on this or any other drawings, or illustrations in the Design and [name]. Since the red lines on these drawings are all consistent with one another, I have considered the appeal on the basis that the red line on the 1:200 scale Block Plan on drawing no (00)_099 Rev 01 identifies the appeal site location. Given that the extent of the red line has no direct bearing on my conclusions on the main issues and that I am dismissing the appeal, I consider that there would not be prejudice to any party as a result of my taking this approach.

The main issues are: i) the effect of the proposal on the character and appearance of the Loughborough Park Conservation Area; and ii) the effect of the proposal on biodiversity and drainage.

The appeal dwelling is within, albeit on the edge of, the Loughborough Park Conservation Area (‘the CA’). It is part of a terrace predominantly comprising buildings of matching appearance, including stucco detailing; a regular arrangement of fenestration, rear outrigger projections, canted front bays, steps up to raised entrances; and an intact roofscape of distinctive ‘London’ roofs which are exposed to the rear. Apart from some replacement UPVC windows, few other external alterations are apparent, and there is an attractive rhythm and a strong sense of uniformity to the terrace group. As part of this group, I find that the appeal building makes a positive contribution to the character, appearance and thus significance of the CA.

The proposed mansard extension would have a very shallow upper pitch angle, contrary to guidance within the Building Alterations and Extensions Supplementary Planning Document 2015 (‘the SPD’) that upper pitches of traditional mansards should be at 30 degrees. The resulting form would be awkward and uncharacteristic, and the unsympathetic nature of the mansard would be exacerbated by the use of aluminium cladding which would stand out against the host dwelling and terrace and which would be contrary to further guidance in the SPD that roof pitches should be natural or reconstituted slate.

Moreover, the SPD identifies that London roofs are part of Lambeth’s and London’s local distinctiveness. Although it would be stepped back from the roof eaves, the development would fundamentally alter the roof form of the appeal building, and I find that it would effectively subsume the existing London roof causing harm to the architectural integrity and character of the building.

The mansard would be set behind the front parapet wall. However, I saw that the front chimney stack along the party wall with [address] which is also behind the parapet is visible from some points on [address], and more clearly from within sections of [address] located opposite the appeal site and between [address] and [address]. The mansard would be of similar height to the chimney stack, albeit below the chimney pots, and would extend closer to the front of the building. Based on my observations at my visit, the top of the mansard would be appreciable in views from [address] and [address], and I cannot agree with the appellant that it would not be visible from the public realm. Where it would be visible, the mansard would stand prominently above the lower roofs of the rest of the buildings in the terrace as an incongruous feature that would significantly and harmfully disrupt the apparent uniformity of the roofline.

Given these factors, I find that the mansard roof would be conspicuous and that it would cause significant harm to the character and the appearance of the host building and the terraced group of which it is part with consequent harm to the distinctiveness of the area and the significance of the CA.

To the rear of the dwelling, the door to the rear of the outrigger would be replaced with a window, and a new window would be inserted to the upper ground floor level above. The style and proportions of these windows would differ from existing windows to the rear of the terrace, and the upper ground floor window would stand out against neighbouring buildings which do not include fenestration to the rear of the outriggers at upper floor levels. In my assessment, these alterations would appear uncharacteristic, detracting from the composition and integrity of the host building and eroding the consistency of the rear elevations of the terrace. The Council suggests that the rear of the building would be visible from trains on the line running to the rear of the site, but even if there are no public views as the appellant asserts, there would be views from neighbouring gardens. These views do make some modest contribution to the character of the building and the significance of the CA, and this contribution would be diminished by the proposal.

The Loughborough Park Conservation Area [name] 2020 notes that UPVC windows to buildings on [address] are a poor match for the original sash windows and detract from the appearance of the street. Subject to further details of their materials and design, I agree with the main parties that the replacement of existing UPVC windows to the front of the dwelling with sash windows would be a heritage benefit of the proposal. The removal of security grilles from two lower ground floor rear windows, the replacement of the existing PVC downpipe to the front of the building with aluminium and repair to stucco detailing would also enhance the fabric and appearance of the building and would be a heritage benefit.

However, even when considered cumulatively, the interventions would be relatively minor, and I find that the visual impact would be very modest in comparison to the conspicuous mansard roof extension. In my judgement, these heritage benefits would not be sufficient to outweigh or offset the combined adverse impacts of the development that I have identified, and I find that there would overall be harm to the character and the appearance of the host building and the CA.

Having regard to the nature and scale of the development and the localised impact, I find that the harm to the significance of the CA would be less than substantial in the terms of the National Planning Policy Framework (‘the Framework’). The Framework therefore indicates that this harm should be weighed against the public benefits of the proposal. In doing so, the Framework states that heritage assets are irreplaceable and great weight should be given to their conservation.

The proposal would improve the connection between the appeal dwelling and its garden, and would provide additional and enhanced living space for occupiers. However, these benefits would be mostly private, and would in any event be limited by the small scale of the development. The heritage benefits arising from the replacement of existing UPVC windows to the front of the dwelling, the removal of security grilles, the replacement downpipe and repairs to stucco detailing would be public benefits of the proposal, but I have already identified that these benefits would be relatively modest. Moreover, there is no substantive evidence before me to demonstrate that they could not be achieved in the absence of the appeal proposal. In my judgement, the public benefits of the proposal are insufficient to outweigh the harm that would be caused to heritage assets, a matter that attracts considerable importance and weight.

The Council found that the rear infill extension would be acceptable. Subject to details which could be secured by planning condition, it has also raised no objection to the proposed rooflight over the rear outrigger. I have no firm reason to find differently. However, the absence of harm in these regards is a neutral factor which does not weigh in favour of the proposal.

I have paid special attention to the desirability of preserving or enhancing the character or appearance of the CA in accordance with Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990. For the reasons above, I conclude that the proposal would cause unacceptable harm to the character and the appearance of the Loughborough Park CA, and it conflicts with Policies Q5 and Q22 of the Lambeth Local Plan 2020-2035 (adopted 2021) (‘the LP’). Amongst other things, these policies seek development that sustains and reinforces local distinctiveness and that preserves or enhances the character or appearance of conservation areas. There would also be conflict with Policy Q11 of the LP insofar as it requires that alterations to buildings respond positively to original architecture, roof form, fenestration and locally distinct forms such as group characteristics; and states that roof additions and mansards will not be permitted where they would harm the architectural integrity of the original building or its group.

Notwithstanding the apparent low risk of flooding from rivers and the sea, the Council refers to mapping showing that the appeal site is subject to surface water run-off. The appellant has not disputed that the proposed sunken courtyard together with the rear infill extension would cover more than half of the area of the dwelling’s rear garden. However, while the area of hardstanding would be increased, there is no compelling evidence before me that suitable provision for sustainable drainage to manage surface water within the site could not be secured through a planning condition.

In addition, I saw that much of the area that would be covered was existing patio, or a steeply sloping bank which at the time of my visit was predominantly bare earth. From the information before me, I consider that the value of this part of the site to biodiversity would be likely to be limited, and would not be meaningfully reduced by the proposal. Having regard to the size of the garden that would be retained beyond the courtyard and scope for planting within the courtyard, I also consider that there would be satisfactory provision for soft landscaping and that the extent of hardstanding on the site would not be excessive.

I therefore conclude that the proposal would not cause unacceptable harm to biodiversity and that it could make adequate provision for drainage. The proposal would accord with Policies Q9 and EN5 of the LP insofar as they include requirements broadly for development to minimise surface water run-off and flood risk and seek satisfactory landscaping that protects habitats or areas of nature conservation interest and biodiversity value.

The Council’s fourth reason for refusal raises concern that insufficient information has been submitted to inform assessment of the effect of boundary treatment between the site and [address]. I note that the appellant has commented that the boundary treatment to No 55 does not form part of the proposal description, and that fencing of less than 2m in height could be erected under permitted development rights. However, given that I am dismissing the appeal for other reasons and it could not alter my decision, it is not necessary for me to consider this matter further.

[name] have found that the proposal would be acceptable in respect of biodiversity and drainage, this does not outweigh the harm that I have found would be caused to the character and appearance of the CA. The proposal would conflict with the development plan when it is read as a whole, and material considerations do not indicate that a decision contrary to the development plan should be reached.

I therefore conclude that the appeal should be dismissed.