Appeal 3336289

The appeal is dismissed.

The main issues in the appeal are: • the effect of the proposal on the character and appearance of the host dwelling and the area, and • whether there is sufficient information to conclude that harm to bats would be avoided

The appeal site lies on the eastern side of Stoke Park Avenue. It comprises a large, detached, two storey dwelling set within a generously-sized verdant plot. Stoke Park Avenue is part of a gated private estate where the properties are, in general terms, similar in nature and plot size to the appeal property. The south-eastern rear boundary of the site abuts the [site address] Conservation Area.

The property has an attached triple garage which projects in front of the main elevation and has two dormer windows in the front roofslope. There are five bedrooms with en-suite facilities on the first floor of the main dwelling.

The proposed development is a roof extension of the main house incorporating dormer windows. The existing building has a traditional pitched roof, and the proposal would create a mansard-style roof. The building has one gable projection to the front and two to the rear. These also have traditional pitched roofs. The proposal would create mansard-style roofs to each of these projections similar to the proposed design of the main roof.

The proposal would result in a building of considerable mass and bulk with a form of almost three full floor levels. The appearance would be top heavy and disproportionate, particularly the rear-facing central Juliet balcony dormer structure. The existing dwelling has half hips which gives it a sympathetic, self-effacing design. The loss of these half hips and their replacement with a full width roof contribute to the overly bulky, disproportionate roof extension.

A very strong characteristic common to dwellings in the estate is the use of gables. The proposed change to the partially squared-off shape of gable compared to the existing crisp defined gables on the building would detract from the visual attractiveness of the existing dwelling and would not be sympathetic to the wider area.

The Appellant suggests that there are other nearby properties with mansard style roofs which are similar in design and appearance to the appeal proposal. I saw many dormer windows on nearby houses but no mansard style projections of the kind proposed in this scheme. Even if some exist, I have determined this appeal primarily on the individual merits of the design in relation to the host dwelling and I find that it would be unacceptably harmful.

I have borne in mind that the NPPF (December 2023) encourages the use of airspace above residential development for new homes. The advice is tempered by, amongst other things, a need for such extensions to be well designed and to comply with local design policy and for the external appearance of mansard roof extensions to harmonise with the original building. In this case, the proposal does not meet those caveats and so I can only attach very limited weight to this national advice. 10.On this issue, I conclude that the proposal would unduly harm the character and appearance of the host dwelling and the wider area. It would be in conflict with saved policies EP3 and H11 of the South Bucks District Local Plan (adopted March 1999, [name] 2007 and February 2011) and policy CP8 of the South Bucks District Core Strategy (adopted 2011). [name] of Bats 11.There is no evidence, from a suitably qualified expert, available with the application or appeal documentation which has assessed whether bats might be present at the site. Given that what is proposed is a major roof extension and that there is suitable foraging and commuting habitat and records of bats in the area, there is a reasonable likelihood of bats being present. 12.Advice in Circular 06/2005 states that the presence of a protected species (such as bats) is a material consideration when a development proposal is being considered which would be likely to result in harm to the species or habitat. The Circular goes on to say that it is essential that the presence or otherwise of protected species and the extent that they may be affected by the proposed development, is established before the planning permission is granted, otherwise all relevant material considerations may not have been addressed in making the decision (paragraph 99). 13.Consequently, attaching a ‘pre-commencement of development’ condition requiring bat surveys would not be appropriate in this case and could not overcome the objection to the proposal. Therefore, on this issue, I conclude that there is insufficient information on which to determine that harm to bats would be avoided. The proposal is contrary to policy CP9 of the [name] (adopted 2011).