Appeal 3311973

The appeal is dismissed in respect of the hip to gable loft and rear dormer extension.

The appeal is allowed and planning permission is granted in respect of the single-storey rear extension and front porch at [site address] in accordance with the terms of the application Ref 9248/APP/2022/2237, dated 12 July 2022, and the plans numbered: P01 and P06 so far as relevant to that part of the development hereby permitted.

The description of development in the heading above has been taken from the Council’s decision notice as it more comprehensively describes the proposal, and I note the same has been used in the appellant’s statement.

As highlighted by the Council, the roof alterations that have already been carried out do not entirely reflect the application drawings. However, the description on the application form is clear that retrospective planning permission was sought for the development ‘as constructed’. I have therefore determined the appeal on that basis.

The Council’s decision notice references Policy DMHB12 of the Hillingdon Local Plan: Part 2 - Development Management Policies (2020) (the DMP), but as the policy relates to ‘Streets and Public Realm’ it is of limited relevance to this appeal.

The main issue in this appeal is the effect of the hip to gable loft extension and rear dormer on the character and appearance of the host building and surrounding area.

The appeal site is one half of a pair of semi-detached houses situated in an established residential area of similar properties.

The change from a hipped roof to a gable end on just one side of the building has significantly altered its form and unbalanced the symmetrical relationship of the semi-detached pair. This unfortunate effect is further compounded by a ridge line that is noticeably higher than the adjoining roof and the use of a drastically different slate roofing material rather than matching the existing concrete tiles.

Furthermore, the dormer is a bulky structure that occupies most of the extended rear roof slope and is built flush to the gable end with a rendered side that is indistinguishable from the rest of the gable elevation. Its excessive size and box-like form is not in keeping with the form and proportions of the host building and creates the impression of a flat-roofed third storey at the rear.

The overall result is a scale and design of development which does not integrate sensitively with the host building, deeply harming its character and appearance.

I saw various other hip to gable changes with rear dormers in [address], some of which have been highlighted by the appellant. Nonetheless, they are not positive features; nor are they of such overwhelming predominance that the prevailing hipped roof character of the street scene has been eroded or changed beyond recognition. Moreover, the adjoining and immediate neighbouring properties all have hipped roofs which highlights the incongruousness of the development at the appeal site. The presence of other apparently similar development is therefore not a good reason, on its own, to allow further harmful development. In addition, the lack of a conservation area designation does not alter the requirements of the development plan and the National Planning Policy Framework (the Framework) in respect of achieving good design and seeking to protect the character of an area.

For all these reasons, I find that the hip to gable loft extension and rear dormer unacceptably harms the character and appearance of the host building and its surroundings. In this regard, the proposal is contrary to Policy DMHD1 of the DMP where it 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, nor raising of the main roof above the existing ridgeline of a house, and requires roof extensions to be subservient to the scale of the existing roof, employ matching materials, and to ensure that there is no adverse cumulative impact on the character, appearance or quality of the existing street or wider area. I also find conflict with the more general requirements of Policy DMHB11 of the DMP; Policy BE1 of the Hillingdon Local Plan: Part 1 – [name] (2012); Policy D4 of the London Plan (2021); and chapter 12 of the Framework, which taken together, 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.

However, the single-storey rear extension and front porch did not feature in the Council’s refusal reasons and I note that planning permission has previously been granted for a very similar ground floor rear extension ([name]:9248/APP/2021/3999). I have no reason to find these elements of the scheme unacceptable, and as they are functionally and physically separate from the roof alterations, a split decision can be made to allow the single-storey rear extension and front porch only.

There may be potential to utilise permitted development rights at the site, but such development would not likely be as substantial as the scheme now before me, so it has limited bearing on my assessment of the appeal.

I recognise that the development represents efficient use of the site and would benefit the occupants of the appeal property with improved living space. Even so, this is not justification for the harm that would be caused and the conflict that arises with the development plan and Framework as a whole.

I have had regard to the Council’s suggested conditions. However, as the single-storey rear extension and front porch are already in place it is not necessary to impose the standard time limit condition, or any condition relating to materials. The approved plans, in so far as they relate to these elements, are listed in the formal Decision. No further conditions were suggested.

For the reasons given above, I conclude that the appeal should be dismissed in relation to the hip to gable loft extension and rear dormer, but allowed in relation to the single-storey rear extension and front porch. A split decision is therefore issued.