Appeal 6000081

The appeal is dismissed.

The main issue is the effect of the proposed development on the character and appearance of the Ashburnham Triangle Conservation Area (CA) including its effect on the significance of the host dwelling as a non-designated heritage asset (NDHA).

The site is located within the [name]. I therefore have a statutory duty under Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 (the Act) to pay special attention to the desirability of preserving or enhancing the character and appearance of the area.

The CA is a roughly triangular shaped area the periphery of which is defined by main roads with residential streets within. Much of the residential development in the CA comprises terraced properties which vary in scale and design. [site address] is characterised by mid 19th Century terraced housing which exhibits a high degree of consistency in respect of architectural features and its linear form. This gives the area a pleasant, ordered character.

The appeal property is a mid-terraced three storey dwelling which, in common with the other properties in the terrace, has a raised ground floor accessed via steps at the front and a lower ground floor from which the garden is accessed. The significance of the terrace as a NDHA lies in its traditional architecture and materials. The front elevations of the properties within the terrace are generally characterised by the external steps, and decorative features around the windows, front doors and string course. The roofs of the properties within the terrace are also relatively consistent in form and materials. The rear elevations display more variety, although two-storey outriggers with mono-pitched roofs, such as that at the appeal site are a common feature which typify these properties. As such the appeal property is typical of this part of the CA and contributes to its significance.

It is proposed to construct an extension at first floor, on top of the existing outrigger and a single storey rear extension at lower ground floor level. Presently, the outrigger is a secondary, recessive element of the dwelling, which is set down from the main roof. The proposed upwards extension would result in an incongruous addition which would compete with and detract from the proportions and design of the original building. The flat roof would jar awkwardly with the directly adjacent pitched roof appearing bulky in contrast.

Because of its elevated position the proposed extension would be a prominent addition to the building which would be at odds with the majority of the terrace which is free of extensions at first floor level. Consequently, the proposed first floor extension would be a poor design which would fail to respond to the character and appearance of the host dwelling and the terrace. It would detract from the characteristic linear form and from the consistency of design.

Although the property to the east of the appeal site has a three-storey outrigger, this is very much an anomalous example which demonstrates the harmful effect that the proposed extension would have on the character and appearance of the area, even bearing in mind the differences in the proposed design. Therefore, whilst I accept that this does form part of the context of the appeal site, it does not justify allowing further harm to occur.

A single storey extension exists to the side of the outrigger. The proposed extension at lower ground floor level would project beyond the rear of the outrigger and the extension and would be the full width of the plot. The Urban Design Guide Supplementary Planning Document ([name] 2023) (SPD) advises that a rear projection of 3.6m is generally appropriate for single storey rear extensions and that where the original rear wall is stepped then a stepped appearance should be maintained with each stepped wall forming the rear wall of the house.

I recognise that extensions which wrap around a rear outrigger are not uncommon and that some extensions which exist nearby do not fully accord with the SPD. However, in this instance the overall depth of the proposed extension combined with the existing extension, from the main rear face of the dwelling would be substantial and would be disproportionate to the host dwelling. Furthermore, the flat façade of the extension with its large bi-fold doors, would not reflect the stepped design or harmonise with the traditional proportions of the original dwelling. As a result of its overall size and design, even if the extension would not be widely visible, it would nevertheless result in harm to the character and appearance of the host dwelling. Whilst various examples of other extensions have been referred to, I have been provided with limited details of these and on the basis of the information before me, none of these are directly comparable with the appeal scheme.

As required by para 212 of the National Planning Policy Framework (the Framework), great weight should be given to the conservation of a designated heritage asset, irrespective of the amount of harm identified. In this instance the proposal would lead to less than substantial harm to the significance of the CA. Para 215 of the Framework states that where a development would lead to less than substantial harm to the significance of a designated heritage asset, this harm should be weighed against the public benefits of the proposal.

I recognise that the proposed extensions would offer significantly improved internal space for the appellants. However, this is a private benefit to which I ascribe little weight. The lack of harm to the living conditions of the occupiers of neighbouring properties is a neutral matter.

Overall, I find that the proposal would not bring about any benefits to the public at large. Consequently, there is no clear and convincing justification for the harm which I have identified given the great weight which must be given to the asset’s conservation.

Para 216 of the Framework states that the effect of an application on the significance of a NDHA should be taken into account in determining the application. In identifying harm to the NDHA, the Framework also requires a balanced judgement having regard to the scale of any harm or loss and the significance of the heritage asset. In this case I adjudge the harm to the NDHA to be significant. Consequently, the stated benefits would not outweigh this harm.

As a result of the harmful effects, I have identified above, I conclude that the proposal would neither preserve nor enhance the character and appearance of the CA and would have a significantly harmful effect on the significance of the host dwelling as a NDHA. The proposal would therefore conflict with the requirements of Section 72(1) of the Act, and Policies D3 and HC1 of the London Plan: The Spatial Development Strategy for [name] (March 2021) and Policies DH1, DH3, DH(a), DH(h) and DH(j) of the Royal Greenwich Local Plan: [name] with [name] (July 2014). Together these seek to ensure that developments are well designed, respond to their context, contribute to local character, preserve or enhance the character and appearance of the CA and protect and conserve locally listed buildings.

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