Appeal 3309443

The appeal is allowed and planning permission is granted for the erection of a single-storey rear infill extension, with sedum roof and flat skylights, with rear facing parapet and new 'crittal style' rear window and French door panel at [site address] in accordance with the terms of the application, Ref 00647/275/P3, dated 26 May 2022, subject to the following

The development hereby permitted shall begin not later than 3 years from the date of this decision.

The development hereby permitted shall be carried out in accordance with the following approved plans: [name] 0372-PLA-01_A (Location + Block Plan), 0372-PLA-01_A ([name]), 0372-PLA-02_A, 0372-PLA-03_A, 0372-PLA-50_A, 0372-PLA-51_A, 0372-PLA-52_A, 0372-PLA-53_A and 0372-PLA-01_B (Location + Block Plan + [name] + Evacuation Area + Statement).

The materials to be used in the construction of the external surfaces of the development hereby permitted shall match those used in the existing building.

The main issues are the effects of the proposal on the character and appearance of the area, and upon the living conditions at [address] with particular regard to light and visual impact.

The appeal property is a two-storey, semi-detached dwelling located within a residential neighbourhood comprising predominantly detached and semi-detached suburban inter-war housing. It is located within the Osterley Park Conservation Area (CA) which is centred around the historic building and gardens of [address]. The appeal property has a hipped roof with a gablet to the front and two-storey outrigger to the rear. This is mirrored by the attached property at No 273 with a central valley running between both and with shared distinctive tall chimney columns between. The pair are typical examples of their time and contribute positively to the street scene and wider character and appearance of the CA.

The property has an existing single-storey, flat roof extension to the rear of the outrigger. The proposal is to replace this with a single-storey extension to an equivalent depth but which would also fill the void up to the side common boundary with No 273.

The Council’s Residential Extension Guidelines Supplementary Planning Document December 2017 (SPD) deals with single-storey rear extensions at section 4.3 and extensions in conservation areas at section 6.1. Ordinarily, the SPD guidance states that, subject to height limitations to avoid any harmful impacts upon neighbours’ access to daylight and sunlight, it may be possible to build an extension the entire depth of an outrigger and which would wrap around the rear part of the original addition. However, within conservation areas the guidance says that such proposals will generally be refused where two-storey outriggers form a specific feature of the building or rhythm of a terrace.

The proposed extension would extend beyond the recessed rear wall of the dwelling to a depth equivalent to the depth of the existing extension. It would also align approximately with single-storey extensions to the rear outriggers of both neighbouring properties. As such, it would not encroach beyond the established rear building lines of properties in the immediate area. Neither would it dominate the rear garden setting due to the deep gardens enjoyed by No 275 and its neighbours. Given this, and the single-storey scale and proportions of the addition, I find that it would remain appropriately subservient in relation to the host dwelling.

The two-storey outrigger is undeniably a feature part of the property and is characteristic of its surroundings. However, during my visit I saw that these features are seen principally from ground level within the rear garden plots of neighbouring properties, or else from the public domain through gaps between properties or over typical garden boundary enclosures. The ground floor elevations of the properties are generally out of sight, other than from the confines of individual plots. Furthermore, those that could be observed in parts from the appeal site were all altered in a variety of ways at this lower level but without noticeably impacting the wider visual qualities of the area.

The appeal proposal would follow this pattern. The single-storey extension would alter the floor plan of the property but, significantly, it would retain the building’s roofline and profile within its wider setting. The appearance of No 275 within its context would be largely unaffected and as such, whilst the SPD states that such proposals will generally be refused, I do not share the Council’s view that it would harm the appearance of the property. As such, the character and appearance of the CA would be preserved ensuring that its significance as a heritage asset would be unharmed. I am satisfied therefore that the proposal would display the quality of design required by Policies CC1, CC2 and SC7 of the Hounslow Local Plan 2015-2030 (LP) to show proper regard to and maintenance of the area’s context and character. For these same reasons, the proposal would satisfy chapter 16 of the National Planning Policy Framework for conserving and enhancing the historic environment. Living Conditions at [address]

The extension would project 5.3m deep along the shared side boundary with No 273. This far exceeds the 3.65m depth recommended within the SPD for single-storey extensions to semi-detached houses in order to avoid causing unacceptable enclosure and loss of daylight and sunlight received by neighbours.

However, No 273 has an existing single-storey addition immediately adjoining the same boundary and to a depth of 2.7m according to a figure provided by the appellant and which is unchallenged. The appeal proposal would extend beyond the nearest ground floor rear facing openings at No 273 by around 2.6m. This is not excessive and is within a range that is normally considered acceptable by the Council when considering the impact of an extension beyond an original rear wall in terms of daylight, sunlight and enclosure.

Given these circumstances, I do not share the Council’s view that the proposal would harm the neighbours’ living conditions in terms of loss of light, outlook and increased sense of enclosure. I therefore find no conflict with [name] CC1, CC2 or SC7 as far as they seek to ensure that development minimises harm to neighbouring residents. Although not determinative, I note also that there was no objection received by the Council from the neighbour to the planning application.

A condition requiring the development to be carried out in accordance with the submitted plans is necessary to provide certainty. In the interests of maintaining the character and appearance of the area a condition is required to ensure that the proposal is finished with materials to match the existing.

For the reasons given, I find that the proposal would not harm the character or appearance of the host dwelling and that the character and appearance of the Osterley Park Conservation Area would be preserved. I also find that there would be no harm to the living conditions at [address]. Accordingly, in the absence of any other conflict with the development plan, and having regard to all other matters raised, the appeal is allowed.