Appeal 3300420

The appeal is dismissed.

The main issues are (i) the effect of the proposal on the character and appearance of the host building and area; and (ii) the effect of the proposal on the living conditions of the occupiers of [address] with particular regard to light and outlook.

[address] is predominantly characterised by terraces of dwellings of similar overall designs and generally modest proportions. The appeal dwelling sits to one end of a terrace, and has an existing rear dormer, as well as a ground-floor rear extension above which a part first-floor extension is now proposed.

The extension would be set in from the boundary with the adjoining neighbour at [address], but it would still cover a fairly large proportion of the width of the rear of the appeal dwelling, and would add significant bulk and mass to the upper part of the building. In combination with the existing ground-floor extension and large rear box dormer, the extension would be a disproportionate addition relative to the host property and site, and I find that it would dominate and overwhelm the proportions of the dwelling to the detriment of its character. The visual impact of the scale of development on the appeal site would be further exacerbated by the stark contrast with the much more modest scale of other buildings nearby where I saw very few examples of extensions above ground floor level.

Moreover, Policy DMHD 1 of the Hillingdon Local Plan: Part 2 – Development Management Policies 2020 (‘LPP2’) advises that pitched roofs on extensions should be of a similar pitch and materials to that of the original roof and subordinate to it in design. The hipped roof of the extension would be out of keeping with the pitched roof form with gable ends that is typical within the area, and would also contrast with the flat roof to the dormer, resulting in an awkward mix of roof forms to the upper part of the dwelling which I consider would be discordant.

At my visit, I saw that the existing rear extension and dormer are appreciable in views from [address] given an access to the side of the dwelling which provides for spacing to the neighbour at [address]. The proposed extension would be similarly visible, and while I acknowledge that the full scale of the development would not be apparent from the street scene, it would nevertheless stand out as an incongruous feature which would be unsympathetic to the character and proportions of the host building. It would also be plainly visible from neighbouring gardens and windows, as well as from the row of garages to the rear of the site.

For these reasons, I conclude that the proposal would cause unacceptable harm to the character and appearance of the host building and area, and it would conflict with Policy BE1 of the Hillingdon Local Plan: Part 1 – [name] 2012, [name] 11, DMHB 12 and DMHD 1 of the LPP2 and Policy D3 of the London Plan 2021. Together and amongst other things, these policies broadly seek high quality design that respects and is appropriate to local character and that harmonises with the local context; and include requirements that extensions appear subordinate to the main dwelling and respect the design of the original house.

The submitted plans indicate that the development would accord with the requirement within LPP2 Policy DMHD 1 that two storey extensions should not extend into an area provided by a 45-degree line of sight drawn from the centre of the nearest ground or first floor habitable room window of an adjacent property. However, the supporting text to the policy outlines that while the ’45-degree rule’ provides a general guide to what is normally considered acceptable, there may be occasions when an extension is considered unacceptable even if it appears acceptable on paper.

In this case, the development would be set in from the boundary with No 121, but the separation would not be large, and it would project along a fairly significant proportion of the depth of the boundary. It would be much taller than the existing rear extension, and I consider given the modest overall size of the gardens here that the depth and two-storey height of the development would present a highly dominant and overbearing feature when seen at such close range from No 121. The height and additional bulk at first floor level would also give rise to an unwelcome degree of enclosure, and I find that there would be a notable loss of outlook which would harm neighbouring occupiers’ quality of life.

That the extension would not breach the ’45-degree rule’ suggests to me that daylight to No 121 may not be unacceptably reduced. Given however the tight relationship of the extension with this neighbour and the orientation of the site, I am concerned that the greater height of development on the appeal site would be likely to give rise to some increased overshadowing of windows and space to its rear. I have not been provided with substantive evidence to indicate that this would not be the case, nor to show that any shading would be insignificant or unlikely to detract from the living conditions experienced by occupiers of that dwelling.

For these reasons, I conclude that the proposal would cause unacceptable harm to the living conditions of the occupiers of [address] through loss of outlook, and it has not been demonstrated that there would not be further harm as a consequence of light loss. It would accordingly conflict with Policy DMHD 1 of LPP2 insofar as it includes requirements to achieve a satisfactory relationship between development and adjacent dwellings and to ensure no unacceptable loss of outlook to neighbouring occupiers. It would also be contrary to LPP2 Policy DMHB 11 which includes a requirement that development does not adversely impact on the amenity, daylight and sunlight of adjacent properties.

For the reasons given above, I find that the proposal would conflict with the development plan when it is read as a whole, and material considerations do not indicate that a decision contrary to the development plan should be reached. I therefore conclude that the appeal should be dismissed.