Appeal 3373847

The appeal is dismissed.

The main issue is the effect of the development on the character and appearance of the host property, and whether the development preserves or enhances the character or appearance of the Gunnersbury Park Conservation Area (the CA).

The appeal site is a two-storey, end of terraced dwelling situated within one of several groups of similar short terraced properties on [address] within the CA. The appeal property has been previously extended, including a two-storey side extension with a ridge height set lower than the dwelling’s main roof line, and a relatively modest flat roof dormer window to part of the rear roof slope. The roof of the appeal property and neighbouring dwellings are visible from a road that serves the garages, outbuildings and the rear of properties on [address]. There are examples of flat roof dormer windows to the rear of other dwellings on [address] with variations in their scale and design, although the majority of the properties along the street do not feature dormer windows.

The significance of the CA derives from its architectural and historic interest, and comprises the historic park and garden of Gunnersbury Park, a cemetery and early inter-war housing estates. The Gunnersbury Park Conservation Area Appraisal (November 2018) (the CAA) highlights the Gunnersbury Park residential estate as a complete and relatively unspoilt example of a 1920s garden suburb estate. The appeal property contributes to the significance of the CA forming part of the group of similar dwellings on [address] identified within the CAA as positive contributors within the Gunnersbury Park Estate character area. Aside from the existing dormer window to the appeal site, other properties within the group at Nos 19 – [site address] do not feature rear roof extensions, with alterations limited to rooflights, thereby appearing as a less altered and more cohesive part of [address] in comparison to other groups.

The proposed dormer would replace the existing modestly scaled dormer window. It would be seen in the context of the property’s extended roof form, sited off the boundary of the adjoining property and slightly more centrally. Nevertheless, due to its height and overall scale, it would fill a notably increased portion of the extended roof, appearing as a significantly larger and bulkier addition. As such, it would appear as a discordant addition to the host property and the wider terrace group.

It is suggested that matching materials to the roof are proposed, however the submitted details indicate that a colour matched, lapped weatherboard external cladding would be used. Despite the matching colour, the proposed cladding would appear prominent against the existing roof tile, accentuating the dormer’s visual impact.

Whilst public views of the proposal would be more limited in comparison to other parts of the CA, it would be clearly visible from the rear access road and other properties in the immediate area. Consequently, due to its scale, position and appearance, the proposal would appear as an unsympathetic and obtrusive feature of the roof, detracting from the character and appearance of the host property as well as the group in which it sits.

The appeal site is a component part of the wider CA, and the contribution that the host property and the group in which it sits make to the significance of the CA would be diminished. Therefore, the development would fail to preserve or enhance the character or appearance of the CA, and it would harm its significance.

As the proposed change would be localised in terms of the CA as a whole, the harm to the significance of the CA would be less than substantial, and this harm would be at the lower end of the scale in that respect. Regardless of the level of harm, the National Planning Policy Framework (the Framework) at paragraph 212 states that when considering the impact of a proposed development on the significance of a designated heritage asset, great weight should be given to the asset’s conservation. Paragraph 215 of the Framework requires the less than substantial harm to be weighed against the public benefits of the proposal.

Whilst the appellant has not specifically referred to public benefits in the appeal submission, the Design and [name] sets out aims for the proposal to ensure internal headroom for a functional and habitable loft space and to maintain respect for the character and appearance of the area. Although there would be some private benefits for the appellant, it would be reasonable to treat these aims as being public benefits insofar that they would contribute to social and environmental objectives set out in the Framework. This includes improving living conditions for occupiers and the overall housing stock in the area, as well as aims to protect and enhance the property within the historic environment. Even so, these public benefits associated with the extension and alteration of a single dwelling are given modest weight and would not be sufficient to outweigh the great weight that I must give to the conservation of the CA and the considerable importance and weight to the less than substantial harm that I have identified to its significance. Furthermore, it has not been adequately demonstrated that the proposed development is the only way to achieve those objectives.

I have also had regard to the appellant’s reference to other dormer window extensions on [address] and in the wider area. I observed some differences to the appeal scheme in terms of their scale, appearance and position in relation to the host property and the surrounding area. I also do not know the full circumstances under which other works were undertaken or their status regarding planning permission. Based on the limited evidence before me, I am not persuaded that other examples are directly comparable to the appeal scheme. In any event, every appeal must be considered on its own merits, as I have done in this case. I therefore cannot draw any direct comparison from these with the development that would weigh in its favour. Whilst they form part of the character of the wider area, these do not justify the harm that I have found.

I conclude that the proposed development would harm the character and appearance of the host property, and it would also fail to preserve or enhance the character or appearance of the CA. It would therefore conflict with Policies SC7, CC1, CC2 and CC4 of the London Borough of Hounslow Local Plan 2015-2030 and Policies D4 and HC1 of The London Plan (2021). Amongst other things, these policies aim to ensure that proposals maintain the character of an area and do not result in harm to the built environment, complement the original building and harmonise with adjoining properties, secure development that responds to an area’s character, promote and support high quality urban design, and conserve the significance of heritage assets.

Similarly, there would be conflict with the Framework where it requires development to be visually attractive as a result of good architecture and sympathetic to local character and history.

Where the proposal has been found to be acceptable in other respects, including the effects on the living conditions of neighbouring residents, these are neutral matters and weigh neither against nor in favour of the development.

Although the appellant has attempted to overcome concerns raised on a previous planning application1, for the reasons set out above, I find that the proposal would harm the character and appearance of the host property and the CA.

The proposal conflicts with the development plan and the material considerations do not indicate that the appeal should be decided other than in accordance with it. For the reasons given above, I conclude that the appeal should be dismissed.