Appeal 3320150

The appeal is allowed and planning permission is granted for the erection of two single storey rear extensions following the demolition of the existing conservatory and timber store at [site address] , Hounslow, Isleworth, [postcode] , in accordance with the terms of the application Ref 00647/179/P12, dated 3 November 2022 and the plans submitted with it.

The description of the development is described on the decision notice and the appeal form as the erection of two single storey rear extensions following the demolition of the existing conservatory and timber store (retrospective). This is a more accurate description and I have determined the appeal on that basis.

The development has already been carried out.

The Council refers to the subdivision of the house into three self contained units for which there is no planning history and which it therefore considers to be unlawful. This is not a matter which forms part of the appeal before me, which relates solely to the construction of the rear extensions and not to the lawfulness or otherwise of the use of the property as three separate units. The latter is not for me to determine and has formed no part of my considerations in reaching my decision.

I consider that the main issues in this case are its effect on the character and appearance of the area and on the living conditions of residents.

[site address] is a two storey semi detached house which has a two storey extension to the side in a style reflecting that of the original house and single storey extensions to the rear which are the subject of this appeal. [address] forms the southern boundary of the listed National Trust property Osterley Park and House. It is in the Osterley Park Conservation Area and is identified in the Council’s Conservation Area Appraisal as part of the parkside character area within the wider conservation area.

The houses along the street are typical of early 20th century residential development and are similar in style and architectural detailing, including gable features, full height bay and bow windows, hipped roofs and a mix of brick and render external materials. Plot sizes are generous with long rear gardens and mature landscaping, giving a spacious appearance to the area. Many of the houses have had large extensions and various alterations.

There is a statutory duty under Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 to pay special attention to the desirability of preserving or enhancing the character or appearance of conservation areas. The National Planning Policy Framework (2021) (the Framework) states that in the consideration of development proposals great weight should be given to the conservation of heritage assets in accordance with the significance of the asset and any harm should require clear and convincing justification.

The policies relevant in this case include CC1, CC2, CC4 and SC7 of the London Borough of Hounslow Local Plan 2015-2030 (the local plan) and the Council’s Supplementary Planning Document Residential [name] 2017 (the SPD). Policies CC1 and CC2 relate, among other things, to design matters and seek to enhance the quality of areas and to protect the living conditions of the occupiers of neighbouring properties to new development. Policy CC4 seeks to conserve the significance of heritage assets. Policy SC7 focuses on residential extensions in general terms regarding their design and impact on neighbouring residents and the SPD sets out more detailed guidance in respect of size and scale.

The single storey rear extensions replace earlier rear extensions which included a conservatory and a timber store. On the basis of the information before me it appears that the earlier structures covered a similar footprint to the new ones. The part which replaces the conservatory has a flank wall approximately 0.7m longer than the latter, with a flat roof across the whole compared with the pitched, glazed roof of the conservatory.

I consider that the new extensions have a more organised and cohesive appearance than the previous ones. Although the larger extension projects further than that advised in the SPD, it is minimal compared with the earlier conservatory which has apparently been in place for at least 20 years, and the increase in size is small in proportion to the rest of the house. It does not adversely impact on the size of the rear garden. The development as a whole has a lower, less cluttered profile which remains subservient to the house and is less obtrusive in relation to the simple form of the rear elevation than some of the large rear extensions evident at several other properties along the street. It is not visible from public viewpoints.

I conclude that the development does not harm the character and appearance of the house itself or the wider conservation area and that it is consistent with local plan policies CC1, CC2, CC4 and SC7 and the SPD.

I consider that, with regard to the neighbouring property, No. 177, the extensions do not amount to a significant increase in a sense of enclosure or loss of outlook or light, or appear more overbearing than the previous situation. The solid flank wall adjacent to the boundary is slightly longer and higher than the solid wall of the previous conservatory, the upper glazed section of which appears to have been higher.

The gardens to both properties are long and orientated from north to south. Accordingly there is already some loss of early morning sun from the garden immediately adjacent to the rear wall of No. 177, but as that faces south there is a good level of available sun and daylight for the rest of the day.

I conclude that the development does not harm the living conditions of neighbouring residents and that in this respect it is consistent with local plan policies CC2 and SC7.

For the reasons given above, the appeal is allowed.

I have considered the conditions put forward by the Council. As the development has already been carried out these are not necessary.