Appeal 3336574

The appeal is allowed and planning permission is granted for erection of single storey rear extension and a rear roof extension with two front roof windows to the house at [site address] in accordance with the terms of the application, Ref 01236/17/P2 dated 24 August 2023, and the plans submitted with it, subject to conditions set out below. (1) The development hereby permitted shall be begun before the expiration of three years from the date of this permission. (2) The development hereby permitted shall be carried out in accordance with the following approved plans: location plan and proposed block plan; and [name]: PP/42/23/02. (3) The materials to be used in the construction of the external surfaces of the hereby approved development shall match those used in the existing building. (4) No additional windows or openings shall be formed in the side elevations of the development hereby permitted.

The Council changed the description of development from that stated on the application form. In the interests of clarity, I consider that the amended description accurately describes the appeal scheme and accordingly I have adopted an amended description in the heading above.

The main issues in this appeal are the effect of the development on (i) the character and appearance of the appeal property and Isleworth Riverside Conservation Area; and (ii) the living conditions of occupants of neighbouring properties.

The site is modest mid terraced property within a predominantly residential area within the Isleworth Riverside Conservation Area. In accordance with the statutory duty imposed by section 72(1) of the Planning (Listed Building and Conservation Areas) Act 1990; I am required to have special regard to the effect of the proposed development on the character or appearance of the area.

Paragraph 205 of the National Planning Policy Framework (the Framework) states that great weight should be given to the conservation of a designated heritage asset when considering the impact of a proposal on such an asset. This is irrespective of the level of harm.

The area is characterised by predominantly traditional two-storey terraced properties, forming a harmonious built form. Properties share common features providing a regular pattern of development.

The proposed development includes a wrap around extension which would extend to a similar position as an existing extension projecting from the rear of the two storey outrigger.

The Council’s Residential Extensions Guidelines, Supplementary Planning Document, A Guide for Householders (2017) (the SPD) state that, rear extensions on terraced properties should not extend more than 3.05 meters from the back of the original house. The guidelines also note that some older homes built in an L-shape, creates two rear walls. In some instances, infilling the full depth of the original outrigger may be acceptable, but where such extensions exceed maximum depth allowances, the eaves of the extension on the boundary wall shared with adjacent properties should not exceed 2meters in height with a 45 degree roof pitch.

The proposed single storey extension would extend beyond 3.05metres, would have an eaves height in excess of 2metres, and would wrap around the outrigger.

Notwithstanding this, it is important to recognise that such guidance does not constitute a ‘black and white’ set of rules to be applied rigidly or exclusively when other material considerations indicate that an exception may be appropriate.

The existing single storey extension to the rear of the outrigger whilst modest in design extends the built form of the property beyond the outrigger. The neighbouring property, No. [address] has a lean-to extension infilling up to the end of their outrigger with a single storey extension projecting from the outrigger, however this is set off the sharded boundary.

Whilst there would be a difference in design between the properties, I do not find that the extension would be incongruous to the property or area in general.

In terms of the proposed rear dormer, I observed during my site visit there are a number of dormer additions on properties within the area. Whilst these vary in design dormers are a common feature in the area.

The SPD confirms that dormer additions should be of modest size and not dominate the roof. As a rule they should be less than half the width (i.e. from party wall to party wall) of the original roof, set down one metre from the ridge and one metre above the eaves. A central position is usually preferable, and the extension should reflect the design of the original building. A pitched or hipped roof may be required.

The proposed dormer would be set in from the side boundaries of the roof by 0.5 metres, would be set up from the eaves by 0.7 metres, but would not be set down from the ridge of the roof. Whilst centrally positioned the dormer would be substantial in size in comparison to the existing roof. Nevertheless the box dormer additions existing on nearby properties vary in size, some are similar to the proposal before me and not set down from the ridge. Whilst these may have been installed prior to the adoption of the SPD, nonetheless they form part of the character and appearance of the area.

The front rooflights are modest in terms of scale and design and do not appear out of keeping with the property or area in general.

I find that the proposed development does not harm the character and appearance of the appeal property and [name] conservation area.

There is no conflict with Policies CC2 and SC7 of the London Borough of Hounslow Local Plan, [name] 2015-2030 (the Local Plan), which seek amongst other things for developments to harmonise with the adjacent properties, preserving the character of the streetscene.

There is also no conflict with the Framework which seeks to ensure developments are of good design appropriate and sympathetic to their surroundings and that the historic environment is protected.

The proposed single storey extension would be similar in depth to the existing extension projecting beyond the outrigger, this would align with the existing rear wall of the neighbouring property No. [address]; as such, the Council consider that the proposed impact on no.15 is acceptable. I do not disagree.

The Council confirm that the proposed single storey extension would project 2.063metres beyond the infill extension at No. [address]. The extension would extend along the shared boundary between the properties and would be 2.4metres to the eaves.

A window exists in the rear elevation of the lean-to extension at No. 19 which extends up to the rear outrigger; a window also exists in the side of the lean-to extension projecting from the rear of the outrigger. The proposed development would provide a small area which would create a sense of enclosure. Notwithstanding this I find this similar to other relationships, in particular the appeal property has a sense of enclosure from the existing lean-to extension at No. 19 and the area to the side of the existing outrigger where a dinning room and kitchen window exists. This is not an unusual relationship for houses of this type.

The Council did not raise issue with regard to the rear dormer or front rooflights in terms of the effect on the living conditions of neighbouring properties from the information before me I do not disagree.

I conclude that the development would not harm living conditions of the occupants of neighbouring properties. There is no conflict with Policies CC1, CC2 and CC4 of the Local Plan which amongst other things seek to protect the living conditions of neighbouring residents.

For the above reasons I conclude that this appeal should be allowed.

I have imposed a standard condition relating to the commencement of development and a condition specifying the relevant plans as this provides certainty. In order to safeguard the character and appearance of the area I have imposed a condition concerning materials. I have also imposed a condition restricting the insertion of windows in the proposed development in the interests of protecting the living conditions of neighbouring properties.