Appeal 3300908

The appeal is dismissed.

The main issue is the effect of the proposal on the character and appearance of the surrounding area, Onslow Village Conservation Area (OVCA) and the significance of the OVCA.

The character, appearance and significance of the OVCA essentially relate to its design as a ‘Garden City estate’ modelled on the ideas of Ebenezar Howard’s Garden City Movement.

The dwellings occupy mature landscaped gardens and face towards narrow roads, often with planted verges and interspersed with areas of open space. The dwellings are harmoniously designed to relate to each other and their positions within the street scape. They are constructed from a limited palette of materials and typically, have uncluttered, steeply pitched roofs, with prominent front facing gables and prominent chimneys. Below roof level the windows are made from timber and have small panes. All of these features contribute to the cohesive village character and appearance of the OVCA and its significance.

As advised in the officer report, the [name] and [name] advises that roof dormers are likely to disrupt the simplicity and clean lines of the villages roofscape and to avoid their insertion.

The appeal dwelling is located close to the junction of [site address] and [address]. It comprises one of a pair of symmetrically designed two storey houses with hipped roofs, large projecting gables at either end and chimneys located centrally and to the rear of each gable. The pair of dwellings are set back from the road behind modest front gardens that are enclosed by hedges.

To the rear the appeal dwelling has a two storey extension with a hipped roof, which projects across approximately half the width of the dwelling. It is similar to the rear projecting wing of the adjacent semi-detached dwelling at 28 [site address] . The appeal dwelling also has a single storey rear extension with a flat roof and large areas of glazing. At roof level the appeal dwelling has three modest sized rooflights within the main roof-slope. Beyond the appeal dwelling the rear garden falls away towards the rear gardens of the adjacent dwellings in [name].

As indicated by the appellant, within the rear garden environment and this part of the OVCA, there are a number of dwellings with dormer extensions. I am not aware of all of their ages or planning status, although note that some pre-date the current development plan policies, supplementary advice and/or the National Planning Policy Framework 2021 (Framework).

Overall, I find that the existing dormer extensions have assimilated into the roofscape with varying degrees of success. The larger box style, flat roofed dormers, which project close to the ridge and eaves lines are particularly prominent. Both individually and collectively they have started to erode and detract from the ordered and uncluttered roofscape. Some of the smaller dormer extensions, particularly those on bungalows and chalet bungalows, have been more successful in blending in with the character and appearance of their host buildings and the OVCA. Accordingly, rather than set a precedent, the existing dormer extensions in the surrounding area serve to illustrate how some roof additions have materially detracted from the character and appearance of the dwellings concerned, their setting and the OVCA. They reinforce the need to assess each proposal on its individual merits and in light of the prevailing planning policies.

Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 requires that when assessing proposals for new development within a conservation area, special attention shall be paid to the desirability of preserving or enhancing its character or appearance. Section 16 of the Framework states that when considering the impact of a development on the significance of a designated heritage asset great weight should be given to its conservation. Any harm requires clear and convincing justification. Paragraph 202 of the Framework states that where a proposal would lead to less than substantial harm to a designated heritage asset, this harm should be weighed against any public benefits that would result from the proposal.

Policy D3 of the Guildford Borough Plan: Strategy and Sites 2019 (LPSS) and policy HE7 of the Guildford Borough Local Plan 2003 (LP), are consistent with this. LP Policy HE7 (3) states that consideration has to be given to the impact of development on the townscape and roofscape of conservation areas.

Amongst other things, paragraph 130 of the Framework states that new development should be visually attractive as a result of good architecture; maintain a strong sense of place and add to the overall quality of the area. Consistent with this LP Policy G5 and LPSS Policy D1 require new development to be designed to a high quality. Development should respond to the distinctive local landscape character and integrate into the existing landscape.

Section 1 of the Council’s Residential Extensions and Alterations Supplementary Planning Document 2018 (SPD), states that the purpose of the guidance is to assist in the design of extensions and advises on the best way to provide extra accommodation, whether they require planning permission or fall within permitted development tolerances. Section 3.3 of the SPD explains that the roof of a dwelling has a major impact on the dwellings character, which forms an important role within the street scene. As such, roof extensions should be positioned to the rear of the property and should be sympathetic and usually subordinate to the existing roof and the dwelling as a whole. Roof extensions should usually sit below the ridge line and occupy no more than half the width or depth of the roof. The proposed fenestration should reflect the proportions and style of the existing windows and normally align with the windows below. Notwithstanding this advice the SPD acknowledges that the borough is diverse in character and that the guidance cannot reflect every individual situation.

The proposed rear dormer would occupy and elevated and prominent position within the rear garden environment. It would project across a significant proportion of the main rear roof-slope and would sit a short distance below the main ridge and above the ridge line of the projecting rear extension. The proposed dormer extension would have a primarily flat roof, which would project out from the existing roof plane by approximately 2.5 metres and its rear elevation would sit close to the rear eaves line. The inner edge of the proposed dormer’s roof would be hipped, which would leave space around the central chimney, resulting in an asymmetric roof design. The proposed rear fenestration would be full height and its depth and proportions would be materially larger than those of the first floor window below it.

As a result of these factors, notwithstanding the use of tile hanging to match the existing roof, the proposed dormer extension would look unduly bulky and top heavy, both in relation to the roof and rear elevation of the dwelling. The roofline of the proposed dormer extension would appear awkward and due to its combined height and width the proposed fenestration would exacerbate the bulky, top heavy and prominent appearance of the dormer extension. It would unacceptably harm the appearance of the host dwelling, the pair of dwellings and the roofscape as a whole. When viewed from within the surrounding rear garden environment, from between dwellings in [name] and from the footpath between [name] and [name], it would materially detract from the character and appearance of the host building, surrounding area and the OVCA.

Due to its siting on the rear roof slope of the appeal dwelling the harm the proposed dormer extension would cause to the significance of the OVCA would be modest and so less than significant. However, as required by paragraph 202 of the Framework, this harm needs to be weighed against any public benefits resulting from the proposal.

During its construction, the proposed dormer extension would provide direct and indirect employment and so would contribute to the local economy. In addition, the proposal would make full and effective use of the existing building and enhance its energy efficiency. However, both individually and together these public benefits would clearly fail to outweigh the harm that would be caused to the significance of the OVCA.

It is acknowledged that the proposed scheme does not affect the front roof-slope of the dwelling, the groupings of the dwellings or any trees. Also, that the chimney is retained and matching materials are used. However, the absence of harm to these features does not mitigate the harm that would be caused by the proposal. Further, the harm to the character, appearance and significance of the OVCA that would be caused by the proposed development would outweigh the personal benefits for the appellant and their family that would result from the proposed additional light, headroom and increased insulation within their existing second floor bedroom.

Finally, it is acknowledged that, if located outside the OVCA the proposal may fall within the permitted tolerances for a rear dormer extension and so would fall outside the scope of the policies and proposals within the development plan. However, as the proposal is within a conservation area, it needs to be assessed against the prevailing policies and advice. Although some of these policies may be old, in relation to the LP policies cited above, they are consistent with the Framework and the LPSS.

I conclude that the proposal would materially harm the character and appearance of the host dwelling, the surrounding area and the OVCA. The less than significant harm the proposal would cause to the significance of the OVCA would not be outweighed by any public benefits. Accordingly, the proposal would conflict with [name] G5 & HE7, [name] D1 & D3, section 3.3 of the SPD and Section 16 and paragraph 130 of the Framework.

I note the concerns expressed by the appellant regarding the handling of various applications and a pre-application submission relating to the appeal dwelling. This is not a matter that affects the merits of the appeal proposal and so it falls outside the scope of this appeal. It is something that would need to be pursued with the local planning authority.

The conclusion on the main issue amounts to a reason for dismissing this appeal, which could not be satisfactorily addressed through the imposition of