Appeal 3313370

The appeal is dismissed.

The Council made its decision on amended plans (RevD). I have determined the appeal on the same basis.

The main issue is the effect of the development on the character and appearance of the host building and surrounding area.

The appeal property is one half of a pair of semi-detached houses located prominently at the corner of [address] with [address] in an area of similar properties. Although both houses have two-storey extensions at the side, these have been designed in a manner that still retains the original hipped roof form and symmetry of the pair.

Policy DMHD1 of the Hillingdon Local Plan: Part 2-Development Management Policies 2020 (the DMP) states that the Council will not support poorly designed or over-large roof extensions including proposals to convert an existing hipped roof to a gable, and requires roof extensions to be subservient to the scale of the existing roof and located below the ridge tiles. It also requires alterations and extensions to respect the design of the original house and to ensure that there is no adverse cumulative impact on the character, appearance or quality of the existing street or wider area. More generally, Policy DMHB11 of the DMP; Policy BE1 of the Hillingdon Local Plan: Part 1–[name] 2012 (the SP); Policy D3 of the London Plan 2021 (the LP); and chapter 12 of the National Planning Policy Framework (the Framework), require new development to be well designed; respect the design and architectural composition of the original building; harmonise with the local context; and add to the overall quality of the area, amongst other things.

Whilst the proposal would retain the hipped roof end on the side extension, this would not prevent the hip-to-gable alteration of the main roof from substantially altering the form of the host property and unbalancing the semi-detached pair. Having a hipped roof set back and down from the new gable-ended main roof would also appear particularly odd in design terms. Furthermore, the rear dormer would subsume the majority of the original rear roof slope and would not be set down from the ridge line. Its excessive size and box-like form would be out of keeping with the form and proportions of the host building and would create the impression of a flat-roofed third storey at the rear. The overall effect would be a scale and design of development which does not integrate sensitively with the host building, harming its appearance.

Though views of the rear dormer would be limited to the gardens and windows of neighbouring properties at the rear, the hip-to-gable alteration would be very visible from the road. In any event, limited public visibility is not a good reason, on its own, to avoid good design and compliance with the relevant requirements of the development plan and associated guidance. Indeed, paragraph 134 of the Framework is clear that development that is not well designed should be refused, especially where it fails to reflect local design policies and any local design guidance and supplementary planning documents.

I acknowledge that there are other hip-to-gable changes with rear dormers in the area. However, they are in the minority and are not positive features. Their presence is not justification for further harmful development that would cumulatively erode the character of the area over time, notwithstanding this is not a conservation area.

For all these reasons, I find that the development would unacceptably harm the character and appearance of the host building and its immediate surroundings. Thus, the proposal is contrary to the relevant provisions of Policies DMHD1 and DMHB11 of the DMP; Policy BE1 of the SP; Policy D3 of the LP; and chapter 12 of the Framework.

I note the appellants’ reference to use of permitted development rights, but as they have themselves described such an option as ‘impractical’, I am not convinced that there is a genuine fallback position in this case and I attach little weight to this matter.

The additional living accommodation would undoubtedly be of benefit to the occupants of the appeal property. Nonetheless, this is not justification for the harm I have identified and the resultant conflict that arises with the development plan as a whole.

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