Appeal 6002171

The appeal is dismissed insofar as it relates to the roof extension including rear dormer window and 2no. front facing rooflights. The appeal is allowed and planning permission is granted insofar as it relates to the single storey rear extension with rooflight at [site address] , Whetstone, Barnet, London [postcode] , in accordance with the terms of the application, Ref 25/3793/HSE, subject to the following conditions;

The development hereby permitted shall begin not later than three years from the date of this decision.

The development hereby permitted shall be carried out in accordance with the approved plans insofar as the single storey rear extension and rooflight only: SH-100, SH-101, SH-105, SH-106, SH-107, EX-SH-001.

The external materials of the extension hereby permitted shall match those used in the existing dwelling.

The site visit was undertaken by a representative of the Inspector whose recommendation is set out below and to which the Inspector has had regard before deciding the appeal.

The description contained in the banner heading above is taken from the Council’s decision notice as it more accurately and succinctly describes the development proposed. I am satisfied that there would be no prejudice to the appellant in using this description.

The main issue is the effect of the proposal upon the character and appearance of the host dwelling and surrounding area. Appeal Planning Officer 6002171

The appeal site comprises a two storey, semi-detached dwelling with a tall, steeply sloping dual-pitched roof, situated within a residential area. The modern estate exhibits a distinctive and coherent architectural character, with a consistent palette of materials contributing to a strong sense of visual unity. Within this overall cohesion, the dwellings are arranged in small clusters that introduce subtle variations in layout and design, adding interest and legibility without undermining the estate’s collective aesthetic. As a component part of the estate, the appeal site contributes positively to the unified character of the area.

The dual-pitched roofscape within the estate is distinctive and largely preserved as originally built. Where dormer windows are present, they are small scale half-dormers such that they form a subordinate feature to the main steeply sloping roof. In contrast, the proposed rear roof extension would represent a substantial addition, extending almost across the full width and depth of the rear roof slope leaving little, if any, of the original roof visible, contrary to the guidance in the Barnet Residential Design Guidance, Supplementary Planning Document (2016) (SPD). As a result, it would appear visually dominant and bulky, introducing an incongruous feature that would disrupt the largely unchanged roof profiles of the appeal dwelling, the adjoining property and the wider development.

Given the separation gap between the appeal site and that of the neighbouring property, together with the lower ridge height of the side projection at No.17, the rear dormer would be visible in glimpses from within the public realm. The proposed dormer extension would also be visible at the rear from surrounding dwellings. As part of a pair of semi-detached dwellings, it would unbalance the roofscape and rear elevation to the detriment of the defined character of the pair. Whilst the use of matching materials and fenestration would contribute to assimilating the proposal into the roof space of the host dwelling, they would not mitigate the impact arising from its scale, form and bulk.

The appellant has stated that the proposed rear dormer extension would create an additional bedroom for their growing family. Whilst the proposal would optimise use of the roof space, it does not outweigh the harm I have identified to the character and appearance of the appeal property and the wider area, and I have therefore given it limited weight in my decision.

The appellant refers to a 2-storey extension including dormers which has been granted planning permission at No 51, a detached dwelling located elsewhere within the estate. I have no details regarding this proposal and the reasons why permission was granted. I am therefore unable to consider the schemes comparable. Furthermore, I have considered the current proposal based on its individual merits.

The proposal includes rooflights on the front roof slope. Front facing rooflights are visible within the public realm and form part of the established character of some dwellings within the development, including the neighbouring property at No.17, which is of a differing design to the appeal dwelling. The proposed rooflights would not appear incongruous within the public realm, nor would they serve to significantly unbalance the appearance of the pair of semi’s, given they would sit flush with the roof slope. Appeal Planning Officer 6002171

A number of the dwellings, particularly within the central clusters, incorporate single-storey flat roof rear projections as an integral part of their original design, contributing to variation in built form while remaining consistent with the overall architectural character of the development. The proposed single storey flat roof rear extension would reflect this design feature and would not, therefore, appear incongruous.

The proposed single storey rear extension would accord with the Barnet London Borough, Residential Design Guidance, Supplementary Planning Document (2016) (SPD) as it would be below the recommended rear projection of 3.5 metres it suggests is acceptable for semi-detached properties. The scale of the rear extension would make it a subservient addition to the host dwelling. The dwelling and plot are of a sufficient size to accommodate the rear extension without it appearing disproportionally large and overly prominent. The visual impact of the proposal from within the public realm would be limited, given its location at ground level, the flat roof design of the proposal and the layout of the dwellings. Therefore, the proposed single storey rear extension would not harm the character and appearance of the host dwelling or surrounding area.

As the single storey rear extension is physically and functionally severable from the proposed rear roof extension, it is capable of being built independently. A split decision would be appropriate in this instance.

I conclude that the proposed rear roof extension would have a harmful impact on the character and appearance of the host dwelling and surrounding area. It would conflict with Policy CDH01 of the London Borough of Barnet Local Plan (2025) (LP) which seeks amongst other things, high quality design and development which responds sensitively to the distinctive local character. It would also conflict with Policy CDH05 of the LP which seeks amongst other matters, proposals that are subordinate and complement the character of the existing dwelling. The proposed single storey rear extension with rooflight would not adversely affect the character and appearance of the host dwelling and the surrounding area. It would therefore be in accordance with Policies CDH01 and CDH05 of the LP and the SPD as described above.

For the approved element of the proposal, conditions relating to the commencement of development and for it to be carried out in accordance with the approved plans are necessary for certainty and clarity.

In the interests of protecting the character and appearance of the dwelling and surrounding area, a condition is necessary requiring the external materials of the extension to match those used in the existing dwelling.

For the reasons given above I recommend that the appeal should be allowed in part and dismissed in part.

I have considered all the submitted evidence and my representative’s report and, on that basis, the appeal should be dismissed in relation to the rear roof extension. However, in relation to the single storey rear extension, the appeal should be allowed.