Appeal 6000110

The appeal is dismissed.

The right of appeal is given only to the original applicant, which is the person / company name on the application form submitted to the Local Planning Authority. This has been reflected in the banner heading above.

The main issue is whether the proposed development would preserve or enhance the character or appearance of the [address] Mortlake Conservation Area.

The appeal site comprises [site address] (No 123), a mid-terrace 3-storey dwelling located in a dense residential area. The site is in the [address] Mortlake Conservation Area (conservation area). The Planning (Listed Buildings and Conservation Areas) Act 1990 (as amended) provides at s72(1) that with respect to any buildings or other land in a conservation area, special attention shall be paid to the desirability of preserving or enhancing the character or appearance of that area.

The relevant Conservation Area Study1 describes the special character of the conservation area as the complex of 19th century buildings, which make up the conservation area, read as a whole, with imposing 3-storey buildings on the street corners and the houses becoming more and more modest as they are distanced from [address], and that these [address] buildings provide a visual gateway into the Grove. The significance of the conservation area, when considered as a whole, derives in part from the architectural and historic interest exhibited by this complex of 19th century buildings, which includes traditional architectural features and materials. 1 Conservation Area Study - [name] no. 16, [address] no. 53 & [name] no. 34.

No 123 is a Building of [name], which together with Nos 117 to [address], forms part of a short terrace group of 3-storey buildings which are also Buildings of [name]. Paragraph 216 of the National Planning Policy Framework (the Framework) provides that, amongst other things, in weighing applications that directly or indirectly affect non-designated heritage assets, a balanced judgement will be required having regard to the scale of any harm or loss and the significance of the heritage asset.

The heritage significance of No 123 arises mainly due to its architectural style and surviving original features as a late 19th century terraced dwelling, its close visual relationship and group value with the wider terrace of which it forms a part, and its positive contribution to the street scene and the character of [address] as a whole. No 123 accordingly contributes to the significance of the conservation area by virtue of it comprising an important part of the complex of 19th century buildings due to its architectural and historic interest.

The height of the eaves and the ridge line of the rear roof slope of No 123 mirrors that at [address] (No 121), which is a 3-storey property of a similar design to No 123. The ridge lines of [address] (No 119) and [address] (No 117) are higher than that at No 121, but not significantly so. Even taking account of the prominent rear roof extension at [address] (No 125), the shallow roofscape of No 123, with its modest design and profile, is in keeping with the wider terrace group.

The proposed development would introduce a rear mansard roof extension, and would raise the main roof ridge of No 123. Due to the scale and bulk of the proposed extension, the currently modest appearance of the rear roof slope would be eroded. The shallow roofscape, referred to above, would be completely lost. In this regard, the proposed development would conflict with paragraph 8.1.1 of the [name] and External Alterations Supplementary Planning Document (adopted 2015) ([name]) which provides that, amongst other things, raising the ridge of the building is normally unacceptable, and that roof extensions should not dominate the original roof.

No 123 would no longer appear visually congruent with the remainder of the wider terrace group of 3-storey buildings referred to above. The proposed development would accordingly not result in the sympathetic adaptation of this Building of [name], as advocated by paragraph 4.1 of the Buildings of Townscape Merit Supplementary Planning Document (adopted 2015). It follows that the proposed development would harm the significance of No 123 as a non-designated heritage asset. Its heritage value to this and future generations would be compromised.

No 117 is situated on the corner between [address] and [address]. The maximum height of Nos 119 and 117 are similar to the maximum height of [address], on the opposite corner. The relevant Conservation Area Statement refers to these buildings as forming a gateway to the conservation area. When seen from [address], due to its considerable scale and bulk, the proposed extension would reduce the visual prominence of these properties, which is currently a distinctive architectural characteristic of the conservation area.

The proposed development would bear similarities with the existing extension at No 125. The Officer’s Report relating to that extension mentioned that limited views of the mansard would be available from public areas. However, I observed that this is not the case, as the development is clearly visible from both [address] and [address]. Consequently, the Council’s assessment in this respect is not persuasive. In any event, the development at No 125 has significantly disrupted the modest appearance of the original roof form of the building. As such, the extension at No 125 does not provide a desirable precedent. Its presence would not alter the proposed development’s unambiguous conflict with the [name] mentioned above, nor the adverse impacts identified. Accordingly, the existing extension at No 125 does not alter my findings on this main issue.

The planning permissions referred to at [address] and [address] relate to properties which are not Buildings of [name]. No plans have been provided relating to these permissions. Hence, it has not been demonstrated that these examples are directly comparable with the proposed development. The submitted [name] aerial photograph of the site and the surrounding area shows that a number of nearby properties have had roof extensions in the past. However, apart from [address] and No 125, all these properties lie outside of the conservation area and therefore are of limited relevance to this main issue. As a result, none of these examples change my findings on this main issue.

It follows that the contribution which No 123 makes to the significance of the conservation area, including to its traditional architectural features, would be unacceptably compromised. The significance of the conservation area would be eroded. The harm caused to the character and appearance of the conservation area would be localised, meaning that the harm caused to its significance would be less than substantial. This harm must be given considerable importance and weight. It must be weighed against the public benefits of the proposed development.

The proposed development would enhance the living accommodation at No 123, to the benefit of its current and future occupiers. I have had regard to the quotes provided from Living tradition ([name]). However, it appears that the additional living accommodation at No 123 would mainly provide private benefits, with minimal public benefits arising. Consequently, these benefits attract little weight. Taking account of the great weight which has been given to the conservation of the designated heritage asset, these benefits would not outweigh the harm that would be caused to the significance of the conservation area.

I therefore find that the proposed development would not preserve or enhance the character or appearance of the conservation area. It would conflict with part A. of Policy LP 1 of the London Borough of Richmond upon Thames Local Plan (adopted 2018) (Local Plan) which provides that, amongst other things, the Council will require all development to be of high architectural and urban design quality, and with part C. of Policy LP 3 of the Local Plan which provides that, amongst other things, all proposals in Conservation Areas are required to preserve and, where possible, enhance the character or the appearance of the Conservation Area.

The proposed development would also conflict with Policy LP 4 of the Local Plan which provides that, amongst other things, the Council will seek to preserve, and where possible enhance, the significance, character and setting of non-designated heritage assets, including Buildings of [name].

The emerging policies referred to in the Council’s decision notice are identical with respect to the relevant parts of the adopted Local Plan quoted above. Therefore, whilst it follows that the proposed development would also conflict with the terms of these emerging policies, this is a neutral matter, which does not weigh either for or against the proposed development.

The support given in paragraph 125 e) of the Framework for upward extensions is contingent on compliance with local design policies and standards, which as explained on the main issue above would not be the case with respect to the proposed development. Little weight has therefore been given to this matter in support of the proposed development.

The proposed development would conflict with the development plan. Taking account of the great weight given to the conservation of the designated heritage asset, which is an irreplaceable resource, I find that the relevant material considerations, including the benefits arising from the additional living accommodation at No 123, do not indicate that the appeal should be decided other than in accordance with the development plan.

For the reasons given above, having considered the development plan as a whole, the approach in the Framework, and all other relevant material considerations, I conclude that the appeal should be dismissed.