Appeal 3361352

The appeal is allowed and planning permission is granted for a rear roof extension to the house at [address], Chiswick, London, [postcode] in accordance with the application [name]/2024/3403, subject to the following conditions:-

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

The development hereby permitted shall be carried out in accordance with the following approved plans: TL_23_[address]_03; TL_23_[address]_04.

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

An application for costs was made by [name] against the decision of the Council of the London Borough of Hounslow and this is the subject of a separate Decision.

The main issues in this case are the effect of the proposed development on:- • the character and appearance of the dwelling and the area; • the living conditions of the neighbouring occupiers, particularly in regard to light and outlook at no [address].

[address] is a three storey semi-detached house built in the late Victorian / early Edwardian period in a residential area that comprises many similar properties. It has already been extended with an approved single storey infill extension and also has permission for a basement extension. Like many of the other dwellings on this side of the street, on the rear elevation it has a two storey outrigger with a flat roof below a parapet wall. There are railings around the parapet wall. The third storey previously had a landing with French windows that provided access onto the flat roof of the outrigger. That third storey element also has a small flat roof that projects beyond the main roof slope.

[name] 2025, after the date of the Council’s decision for this proposal, a Certificate of [name] or Development for a rooftop extension was granted by the Council for a very similar scheme and scale of development to that proposed now, albeit without access to the existing roof terrace (ref P/2024/4309). I saw at my visit that the approved scheme has been constructed but not fully completed. The current proposal, like the approved scheme, would extend beyond the existing landing at third storey level over the existing roof terrace by some 4.35m. Unlike the approved scheme which contains only a small, square window opening and no access onto the remaining roof terrace, it would contain full length opening windows that would provide access onto the roof.

The appellant’s evidence shows that on this side of the road there are other third storey roof extensions at nos 43, 65, 75, 79, some of which are larger than that proposed here although the Council says there is no record of planning permission for no 65 and I have no details of the planning status of the others. I have noted that permission was refused earlier this year for a roof extension to the adjoining property at no 57 but that had a significantly deeper projection at some 7.53m. I have therefore determined this proposal on its own merits.

The extension would project some 4.35m and beyond the 2.5m advised in the Council’s Design Guidance for Extensions and Alterations. Nevertheless, as it would be set back significantly from the rear wall of the outrigger and would not extend across the full width of the outrigger with a height just below that of the existing third storey flat roof, it would not be disproportionate to the scale of the existing house. Its flat roof form would reflect the third storey and outrigger roofs and the proportions of the proposed window opening would reflect those of the existing openings in the main rear wall.

Whilst the adjoining property at no 61 does not have a third floor roof extension, the rear elevations of the appeal dwelling and its adjoining neighbour at no 61 are not generally seen in the same context due to the number of mature trees within the rear garden of no 61. This, and the small scale of the proposal, would therefore mean that any unbalancing impact would not be significantly harmful to the character or appearance of the dwellings, particularly given the location at the rear of the property and the distance from the nearest public viewpoint at [address] which lies beyond the railway line at the end of the garden.

I conclude then that the proposal would not cause significant harm to the character or appearance of the dwelling or the area and would accord with development plan policies CC1, CC2 and SC7 of the Hounslow Local Plan 2015-2030 (LP, 2015) which together seek to ensure that new development is of a high quality that maintains the character of existing areas.

The adjoining property at no 61 has a rear conservatory. The appellant’s plan shows it as a separate room but I saw at my visit that a wall has been knocked through so that it forms part of the kitchen/living area. At first floor level there is a rear facing window that appears to serve a bedroom. The proposal would be set in from the side boundary by just over 3m and would be sited to the north-west of its neighbour.

The Council has not objected in terms of the effect on the privacy of neighbouring residents as it accepts that access to the roof terrace existed previously. I noted at my visit that some of the surrounding properties have also have access onto similar roof terraces although I cannot be certain of the planning status of those. As a result, I find that although the proposal would enable views from the roof terrace across neighbouring gardens and into the kitchen/living room of no 61, the impact on the privacy of neighbouring residents would not be significantly worsened by this proposal than was the case previously.

In regard to daylight and sunlight, the planning officer’s report appears inconclusive because it said that ‘the second floor window and lower ground floor conservatory, may be affected by overshadowing from the height of the proposal...and could result in harm to no 61’s amenity and daylight/sunlight. Further evidence of this, in regards to a sunlight/daylight report will need to be provided to make a conclusive assessment on the impact the proposal will have on the neighbour’s daylight/sunlight’. The appellant’s evidence in the Daylight and [name] indicates that there would be no significant loss of daylight or sunlight to no 61 and I have no sufficiently compelling evidence from the Council to the contrary. On that basis and given the separation and orientation, I am satisfied that would be the case and it would be acceptable in this regard.

However, despite the set in from the side boundary, on the basis of what I saw during my visit and the photographs submitted by a third party, the height of the extension at some 8.5m and its projection of some 4.35m would make it unduly overbearing when seen from the rooms at no 61 referred to above. This would severely impact the outlook of the occupiers and given that people can reasonably expect to spend most of their time in their kitchen or living room and that the bedroom is one of the main bedrooms in the property, this would result in significant harm to their living conditions. As such, the proposal would be contrary to development plan policies CC1, CC2 and SC7 in the LP which seek to minimise any harm to amenity.

The Certificate of [name] or Development is an important material consideration in this appeal. As that fallback position has already been implemented and the harm from that is equally harmful to that which would arise from the current proposal, it carries significant weight that outweighs the harm I have found. Despite the current proposal’s conflict with the development plan in terms of the outlook for the occupiers of no 61, it would be perverse to dismiss this appeal given its similarities to the approved and built scheme and the absence of additional harm from the principal difference of the proposed roof access.

In addition to the standard commencement condition, a condition is necessary requiring that the development is carried out in accordance with the approved plans, to provide certainty. A condition for matching external materials is also necessary in the interests of the character and appearance of the site and the area.

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