Appeal 3350879

The appeal is dismissed.

The description of development was amended between the submission of the application for planning permission and the Council issuing its decision. I have therefore used the amended decision, with minor edits for clarity, in the banner heading above.

On 12 December 2024 the Government published a revised National Planning Policy Framework (“the Framework”), replacing the December 2023 version. The provisions most relevant for determining this appeal were not altered significantly, and as a result I consider that there is no requirement for me to seek further submissions on the revised Framework; I am satisfied that no party’s interests have been prejudiced by my taking this approach. [name] have referred in my decision to specific paragraphs of the Framework, the numbering used is that of the December 2024 version.

Although the appeal site is within the Metropolitan Green Belt, it is common ground between the Council and appellant that the proposal would not be inappropriate development in the Green Belt. Based on all the evidence before me I see no reason to take a different view, so there is no need for me to consider whether or not the development is justified by very special circumstances in respect of its Green Belt location.

The main issue is the effect of the proposed development on the character and appearance of the area.

[site address] is a 19th century two-storey semi-detached house with three bedrooms, on a quiet residential street. It has a tiled pitched roof with a side gable, and a two-storey rear return or outrigger, also with a pitched roof, and a single-storey flat-roofed extension, and is set on a narrow plot with a relatively long rear garden. Other dwellings in the surrounding area are mostly semi-detached, although some are detached or in short terraces of three or more; housing in the area is of various ages and displays a range of styles and designs.

The property is within the Shenley Conservation Area (“the SCA”), and I have a statutory duty to pay special attention to the desirability of preserving or enhancing the character or appearance of the conservation area. Paragraph 202 of the Framework states that heritage assets are irreplaceable and should be conserved in a manner appropriate to their significance. It goes on to say at Paragraph 213 that any harm or loss requires clear and convincing justification, and at Paragraph 215 that any harm that is less than substantial must be weighed against the public benefit of the proposal.

The SCA is large and encompasses distinct character areas; [address] is close to [address] which forms the spine (and is the focus of the historic core) of the village. The appellant suggests that the appearance of [address] has been affected by alterations to the extent that it perhaps should not remain part of the conservation area, though that is not a matter for me to address here. The 2012 [name] acknowledges the changes on [address], but notes that “despite the encroachment of post-war housing and intensive modernisation of many cottages, the picturesque, small-scale charm of the streetscape has not been entirely lost”; I agree and consider the appeal proposal in that light.

The proposed development includes the addition of rear dormer to the rear of the building and two roof lights to the front, along with internal alterations, to create a third bedroom in the loft space. This would allow the first floor to be reconfigured, replacing the third bedroom in the rear outrigger (which is entered through the second bedroom) with a new family bathroom (replacing the existing bathroom which is on the ground floor at the rear of the kitchen).

[name] of The Council’s 2006 Planning and Design Guide Supplementary Planning Document (“the SPD”) provides guidelines for residential extensions and alterations, including rear dormers. It advises that dormers should be as small as possible, occupying no more than 60% of the roof space, and set at least 0.3m below the main roof ridge and above the eaves, and at least 0.5m in from the sides. By the Council’s measurements the proposed dormer would occupy 54% of the roof space and would be set around 0.9m above the eaves, but would be only 0.2m below the main roof ridge and set in only 0.3m from the flank walls; notwithstanding that the Council’s officer report commented that “the dormer complies with the SPD in terms of its size”, it would not in fact comply with all of aspects of the SPD guidance in that respect.

The SPD also advises that the design and style of dormers should match the main roof of the original house and that, where there is an existing rear extension, any dormers on it should remain separate from those on the main roof. The proposed dormer would have a flat roof, so would not be in a matching style; it would straddle the valley between the main roof and the rear return thereby extending over part of the outrigger. The dormer would add substantial mass to the appeal property at roof level, where it would be a cumbersome and insensitive feature; while it would not be visible from public spaces (other than in some views from the service lane at the rear of the property), it would be prominent and incongruous in close or medium views from the surrounding properties and their rear gardens.

The appellant drew my attention to other dormers and rear extensions nearby. The appeal property’s attached “twin” at No [address] has a flat-roofed box dormer, but that is much smaller than that proposed in this case and so is considerably less intrusive. No 10 has a large extension at the rear of the first floor, though from the photograph provided and what I saw on my site visit it has the appearance of a full flat-roofed additional storey rather than anything readily identifiable as a dormer. Similarly, the extension to the rear of No [address], also within the SCA, appears to have infilled the area between two rear wings at first-floor level rather than creating a dormer at roof level. None of these other examples appears directly comparable to, nor weigh significantly in favour of, the appeal proposal.

Several properties on [address], outside the SCA, have large box dormers; I was able to see some of them during my visit, and others in photographs provided by the appellant. None of them appeared to be particularly sensitive additions to their host property, though as far as I could see none appeared to straddle a rear outrigger or extension in the way proposed here. Again, they are not directly comparable to the appeal scheme, and do not weigh significantly in its favour.

Planning permission was granted in May 2024 for alterations to the appeal property, including a rear dormer ([name]: 23/1467/HSE). Given the appellant’s obvious desire to extend the property, it appears to me that there is a very real prospect of that fallback scheme being carried out in the event of my dismissing this appeal. I do not, however, accept the appellant’s argument that that earlier permission establishes that the design, mass and bulk of this appeal proposal are acceptable. The dormer approved in May 2024 would be set further above the eaves, and would be slightly narrower, than that proposed here, nor would it straddle the valley between the main roof slope and the rear outrigger. As a result, the harm I have identified in paragraph 11 arising from the size, form and positioning of the dormer would not be present in the fallback case. I therefore consider that this appeal proposal would be significantly more harmful to the character and appearance of the area than the fallback scheme would be.

I conclude that the proposed dormer would be detrimental to the appearance of the host property, and so would not preserve the character or appearance of the SCA. Given the size of the conservation area as a whole, and the size and siting of the dormer, in the Framework’s terms the harm to its significance as a designated heritage asset would be less than substantial. The scheme would improve living conditions for the appellant and her family, including by resolving the currently unsatisfactory access to the third bedroom, though this is essentially a private benefit which could also be achieved though the May 2024 permission; no public benefits arising from the scheme have been identified.

The development therefore conflicts with Policies CS14 and CS22 of the 2013 [name], and with Policies SADM29 and SADM30 of the 2016 Site Allocations and Development Management Policies Plan (“the SADMPP”). Together, and among other things, these policies seek to ensure that development achieves high quality design which makes a positive contribution to the built environment, and that heritage assets including conservation areas are respected and protected. The proposal also conflicts with the provisions of the Framework which seek to conserve and enhance the historic environment.

The proposed development would not preserve or enhance the character or appearance of the Shenley Conservation Area and would conflict with the development plan taken as a whole. There are no material considerations, including those of the Framework, which indicate that the decision should be made other than in accordance with the development plan.

For the reasons given above, the appeal is therefore dismissed.