Appeal 3324671

The appeal is dismissed.

I have used the description of development on the appellant’s application form, rather than the one shown on the decision notice, because no correspondence has been provided showing the appellant agreed to a revision to their description of development.

The main issue of the appeal is whether the development would preserve or enhance the character and appearance of the Blackheath Park Conservation Area.

The appeal property is a two-storey detached dwelling that was designed in the Arts and Crafts style. The dwelling still benefits from many of its original design details and distinctive plan form, which largely mirrors the plan form of the neighbouring property at [address]. The special significance of the Blackheath Park Conservation Area (BPCA) comes from the quality and diversity of its housing, ranging from grand Georgian and Victorian villas to the Arts and Crafts properties found on [address] which forms part of the Cator Estate South Character Area of the BPCA.

The size and design of dwellings on [address] vary, however what they have in common is that they are all set back from the road by a similar distance and the use of similar materials and architectural features creates a uniformity and an attractive street scene. Therefore, I disagree with the appellant’s Heritage Impact Assessment, which downplays the contribution the appeal property makes to the character and appearance of the BPCA, as I consider it makes a positive contribution.

The appeal proposal would involve a series of alterations and extensions to the dwelling, with the Council concentrating their refusal reason specifically on the proposed part-two, part single-storey rear extensions, roof extensions and the basement extension. The proposed removal of the dormer window on the principal elevation, the replacement dormer on the rear elevation and the introduction of solar panels were acceptable to the Council and I have no reason to disagree. The solar panels would represent a modest environmental benefit to the public.

The Council states that the rear extensions would have an uncharacteristic form, however in terms of the two-storey rear extension, the plans show they would effectively involve elongating the existing structure, whilst replicating its current form. The asymmetrical catslide roof structure would be replicated wrapping around the side elevation at ground floor level consolidating part of the existing timber lean-to structure. Subject to a condition securing design details such as sample building materials, I find this element of the appeal proposal would be acceptable.

The single-storey rear extension would protrude beyond the new two-storey rear extension. This would cause the extension to be out of character with the host property, rather than remaining subservient to it in terms of its depth, scale and design. It appears this has been contrived to create the rear light well for the basement extension. Policy DH(a) of the Royal Greenwich Local Plan: [name] with [name] 2014 ([name]) states that flat roof extensions would not be accepted on rear elevations when visible from the public highway. Whilst it would not be visible from the public highway, the addition of a flat roof extension to a dwelling which is characterised by pitched roofs, extending beyond the two-storey extension, would appear incongruous with the architecture of the host building. Therefore, the flat roof extension would conflict with [name](a) and DH1 of the [name], the latter of which seeks high-quality design that positively contributes to the built environment.

The rear extensions are proposed in conjunction with an extension of the roof which would see it enlarged in terms of its width and depth. This would fundamentally alter the character of the property causing it to lose its distinctive plan form and the symmetry it has with the neighbouring property. The increased span of the roof structure, cumulatively with the rear extensions described above, would give the dwelling a bulky appearance which would compromise its attractive Arts and Crafts design, and in the process would fail to preserve the character and appearance of the BPCA. Consequently, the roof alterations would conflict with the [name](a)(iii); DH(h)(i); and DH(i) and Policy DH3 of the London Plan which together seek to ensure developments including residential extensions are well-designed and preserve designated heritage assets such as the BPCA.

The enlargement of the roof would ultimately fail to be sympathetic to the character and history of the building and it would fail to reflect the local design policies I have cited above. Therefore, this element of the appeal proposal would also conflict with the guidance contained within paragraphs 130 and 134 of the National Planning Policy Framework (the Framework). This element of the appeal proposal would also conflict with paragraph C of policy HC1 of the London Plan (2021) as the cumulative impacts of the extension would harm the character and appearance of the BPCA.

The appeal proposal also includes a basement extension which the Council states conflicts with its [name], Basements and Conversions Guidance SPD 2018 (SPD). The SPD states that basements should generally be limited to the footprint of the host building to remain subordinate in scale. The proposed basement extends beyond the confines of the footprint of the existing dwelling to the front and the rear to create the light wells. The SPD also states that where basements are not a traditional feature of the street, which I consider to be applicable for [address], basements with light wells to the front of the dwelling would normally be refused. Due to the property being set back significantly from the road, the light well at the front would have a negligible impact on the character of the property from the street scene. Nevertheless, due to the floor area of the basement extension being greater than the footprint of the existing dwelling, thereby failing to remain subordinate in scale, this element of the appeal proposal conflicts with the SPD.

I acknowledge that the SPD also requires proposals for basement extensions to include a [name] (SMS) signed and endorsed by a [name] or [name], which has not been provided. However, this is something that is possible to resolve with a pre-commencement planning condition and is not necessarily determinative in my

The Council has cited conflict with paragraphs 199 and 200 of the Framework. Paragraph 199 states great weight should be attributed to the conservation of a designated heritage asset, which in this case is the BPCA. Paragraph 200 states that any harm to a designated heritage asset should require clear and convincing justification. Furthermore, paragraph 202 states that where a development proposal 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 including, where appropriate, securing its optimum viable use.

The harm to the character and appearance of the [name] have identified relating to the single-storey rear extension, the enlargement of the roof and the basement extension is considered to be less than substantial. There are modest public benefits proposed, namely the installation of solar panels. However, this would not outweigh the less than substantial harm I have identified in terms of the design of extensions which would fail to preserve or enhance the character and appearance of the BPCA. Therefore, the appeal conflicts with paragraphs 200 and 202 of the Framework.

Concluding on the main issue of whether the development would preserve or enhance the character and appearance of the BPCA, I have found that the single-storey extension, the enlargement of the roof and the configuration of the basement extension would conflict with [name](a)(iii); DH(h)(i); and DH(i), and Policy HC1, paragraph C of the London Plan. The appeal proposal has been found to cause less than substantial harm to the BPCA as a designated heritage asset, with insufficient public benefits to outweigh the harm, thereby conflicting with paragraphs 200 and 202 of the Framework.

The Council also stated the appeal proposal conflicts with policies D3 and D10 of the London Plan. Policy D3 relates to optimising site capacity through the design-led approach, which is not applicable to a householder extension. Policy D10 instructs [name] to establish policies in their development plans for basement development, which the Council has already done. Policy D10 does not provide any specific guidance on how basement extensions should be configured. Therefore, I have found that these policies were not determinative in my decision.

The appellant has highlighted other extensions that have been permitted on [address] as part of their justification for the appeal proposal. These examples relate to dwellings that differ from the appeal property and the size, design and nature of the extensions differ too. Ultimately, other extensions permitted nearby are not particularly relevant as each case should be assessed on its individual merits, which is precisely what I have done when determining this appeal.

The appeal proposal in terms of its overall design would fail to preserve the character and appearance of the BPCA and, as a result, would conflict with the development plan when read as a whole. I have also identified conflict with the London Plan and the Framework. There are no material considerations of sufficient weight to outweigh the conflict I have identified, therefore I conclude that the appeal is dismissed.