305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision Site visit made on 20 October 2022 by L Hughes, BA (Hons), MSc, MRTPI an Inspector appointed by the Secretary of State Decision date: 03 November 2022 Appeal Ref: APP/F5540/W/22/3294957 305 Whitton Dene, Isleworth, London TW7 7NE • The appeal is made under section 78 of the Town and Country Planning Act 1990 against a refusal to grant planning permission. • The appeal is made by Mr Mahan Mirzanasiri against the decision of the London Borough of Hounslow. • The application Ref 01203/305/P12, dated 2 December 2021, was refused by notice dated 21 February 2022. • The development proposed is a single storey rear/side extension, first floor side and rear extension, and conversion of the property into two self-contained units. Decision 1. The appeal is dismissed. Preliminary Matters 2. The original application form included an error within the appellant’s name, which I have rectified in the banner heading above. 3. At my site visit I saw that building work was underway within the site. Main Issues 4.

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision I note that concerns were raised within the Council’s officer report as to whether the development would provide acceptable living conditions for its future occupiers regarding garden provision, with a potential conflict with policy SC5 of the London Borough of Hounslow Local Plan 2015-2030 (2015). However, this was not a reason why the application was refused, and because the appeal is failing for other reasons, I have not considered this issue any further. Therefore the main issues are: • the effect of the development on the character and appearance of the host property and wider streetscene; and • whether the existing building is suitable for conversion into flats. Reasons Character and appearance 5. The appeal site comprises a 2-storey dwelling with rear dormer on a prominent corner plot, at the end of a short terrace of residential and commercial properties. The wider suburban area is predominantly semi-detached dwellings, with a public open space area opposite the property’s side elevation. The dwelling incorporates several historic extensions, plus a substantial single https://www.gov.uk/planning-inspectorate

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/22/3294957 storey rear extension shown as existing on the plans is under construction. The proposal is for conversion of the dwelling into 2 flats, alongside a ground floor corner extension to join the existing rear and side extensions, plus first floor extensions to the rear and side. 6. Although the extensions proposed within this scheme have predominantly the same external dimensions as a recent permission1, that permission incorporates a narrower corner extension. This appears to be under construction on site, along with the rear and first floor elements. The additional width and proximity to the boundary of the appeal scheme corner extension would be a cumulatively significant difference. 7. The resulting ground floor extension would be wider than half the width of the original dwelling, and it would not all be set in at least 1m from the side boundary, contrary to guidance in the Hounslow Residential Extension Guidelines Supplementary Planning Document (SPD) (2017). This SPD intent is for extensions to remain secondary in size and appearance, and proportionate and subordinate to the dimensions of the main house.

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision The proposal would result in substantial massing which would dominate the rear elevation of the property, which is particularly visible in the streetscene due to its corner location and the open space adjacent. Overall, it would not be subservient and would be out of proportion with the host building. 8. In addition, the hipped roof form of the side extension would create an inharmonious contrast with the existing gable end of the host. While the dwelling is not listed and does not form part of a designated Conservation Area, it is still important to respect the character of the area. 9. In conclusion therefore, the proposed development would result in harm to the character and appearance of the host property and wider streetscene, which would be contrary to the Local Plan policies CC1, CC2, and SC7. It would also conflict with the Residential Extension SPD, and the design principles of the National Planning Policy Framework (‘the Framework’) (2021).

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision Together these seek to ensure that development proposals contribute to an area’s character and support high quality urban design and architecture to create attractive, distinctive, and liveable places, and respond meaningfully and sensitively to site characteristics and constraints, and the layout grain, massing and height of surrounding buildings. Conversion to flats 10. Policy SC6 of the Local Plan aims for the conversion of buildings and the subdivision of existing housing stock to contribute to housing supply without having an adverse impact on the character of an area, or residents’ amenity. Amongst other requirements, for acceptable conversion of houses to flats there is a minimum original floor area threshold of 130sqm. SC6 does not accept this threshold if only reached due to previous extensions, because the impact of multiple occupation on the residential amenity and character of the surrounding established residential area is likely to give rise to serious harmful impact. Therefore, while the parties provide differing figures and interpretations for whether the proposal complies with the threshold, I place more importance on assessing the scheme’s potential impact in this regard.

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision 1 Ref: 01203/305/P14 https://www.gov.uk/planning-inspectorate 2

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision 1 Ref: 01203/305/P14 https://www.gov.uk/planning-inspectorate 2 Appeal Decision APP/F5540/W/22/3294957 11. The intensification of the use into 2 flats would only create a minor increase in movements from the site given the size of the existing property, and is thus unlikely to significantly impact neighbours’ living conditions or cause disturbance. I therefore find that the property is suitable for conversion regarding its floorspace size. Other elements of SC6 are also met including internal and external space standards, and provision of a family unit at ground floor. While criteria (j) also expects development proposals to be of a high quality design, I do not note this to be an overriding element of SC6 considering that I have specifically addressed design policies above. 12. In conclusion I find that the existing building is suitable for conversion into flats and would thus comply with the overall intent of Local Plan policy SC6. Other Matters 13. I accept that the intensification of the site would contribute to housing supply targets, however, the net benefit of 1 unit is minimal and therefore this is only a very minor benefit.

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — Appeal Decision The enhanced living accommodation and improved energy performance for the appellants’ family is a private benefit which does not outweigh the harm as identified above. Conclusion 14. The proposal conflicts with the development plan as a whole. With no other material considerations outweighing this conflict, for the reasons given above I conclude that the appeal is dismissed.

305 Whitton Dene, Isleworth, Hounslow, London, TW7 7NE — London Borough of Hounslow — L Hughes INSPECTOR https://www.gov.uk/planning-inspectorate 3