Appeal 6000386

Appeal A is dismissed.

Appeal B is dismissed.

There are two appeals relating to similar proposals on the same site. The schemes were refused on the same date and differ only in respect of the design of the proposed rear mansard outrigger extension. I have dealt with each case on its individual merits, but to avoid duplication, both appeals are considered together in this decision, except where otherwise indicated.

The description of development on each decision notice states that the applications comprise a variation of planning approval 24/0979/HOT. However, the descriptions of development for both appeals in the banner heading above are taken from the application forms and supporting letters submitted with each planning application, as well as the appellant’s subsequent written confirmation that both applications relate to a proposed variation of condition No.4 of permission Ref 25/0182/VRC.

For clarity, approval Ref 25/0182/VRC granted a variation of an earlier permission Ref 24/0979/HOT, dated 29 July 2024, for extension of the existing basement including the addition of front and rear light wells; a single storey rear extension; a part single/part two storey side extension; an extension to the roof; and replacement railings.

As such, [name] and B each seek further cumulative changes to permission Ref 24/0979/HOT, as amended by approval Ref 25/0182/VRC. Appeal A proposes to increase the width of the rear mansard outrigger to the full width of the extended dwelling and Appeal B proposes to extend its width by 2.1m.

The main parties have confirmed that the decision notice for 25/0182/VRC contains a typographical error and that the listed approved plan ‘A10_EO1 [name] should be ‘[name] drawing Ref A10_P01 [name]. I have dealt with both appeals accordingly.

Since the determination of the applications the subject of these appeals, the Council has adopted the Richmond Upon Thames Local Plan ‘the best for our borough’ 2024 to 2039 (7 October 2025) (the Local Plan). This supersedes the previous London Borough of Richmond Upon Thames Local Plan (July 2018). The main parties have had the opportunity to comment upon the implications of the adoption of the Local Plan.

The main issue in the case of both appeals is the effect of the proposal on the character and appearance of the host property and the wider surrounding area.

The Council’s view is that an extension to the rear outrigger did not form part of the original and subsequently amended approved schemes, and that, as such, it would necessitate a change of development description, so that it cannot be considered an amendment to the previously approved schemes. Appeal Decisions 6000386 and 6000387

This accords with the Finney Judgment1 which established that an application under s73 may not be used to obtain a permission that would require a variation to the terms of the ‘operative’ part of the planning permission, which would include, the description of the development for which the original permission was granted.

In considering this matter I have had regard to the MHCLG publication Permitted Development Rights for Householders Technical Guidance (September 2019) (the Technical Guidance) which confirms that houses will often have more than two side elevation walls. Having regard to the illustrated example within the Technical Guidance, I am satisfied that the side wall of the original outrigger would comprise a wall forming a side elevation.

As such, the schemes the subject of both Appeal A and Appeal B would fall within the original description of development which includes a ‘part single/part two storey side extension and extension to the roof.’

The appeal property comprises a large semi-detached 3-storey period dwelling with brick walls under a tiled pitched roof, which accommodates the second floor living space. It lies in a prominent location on the corner of [address] and [address] within an established residential area.

The appeal property makes a positive contribution to the [address] streetscape. It forms an integral part of a street scene comprising a row of similarly designed pairs of attractive houses which front both sides of the street. These result in a prevailing uniformity of built development comprising rows of semi-detached houses of a similar height and scale, having consistent front and rear building lines and being set within long rectangular-shaped plots arranged perpendicularly to the road.

The dwellings, including the appeal property, collectively result in a cohesive townscape, having regard to a prevalence of similar materials, roof forms and architectural detailing. These include brick walls, timber sliding sash windows, decorative headers and cills, square front-facing bay windows at ground and first floor level and pairs of matching recessed front porches with decorative surrounds.

The roofscape is characterised by slate and tiled pitched roofs with prominent front-facing feature gables, as well as decorative tile edging, potted brick chimney stacks and parapets. The properties are positioned close to the road frontage with small front gardens enclosed by low boundary walls, so that the design quality of the houses is readily apparent in public views from the street.

The appeal property also has a visible presence within the [address] streetscape where its side and rear elevations, particularly the upper floors which rise above the height of the side boundary wall, are visible in views from the public realm of the street and from neighbouring properties.

Prior to the grant of approval Ref 24/0979/HOT, the property benefitted from a single storey side conservatory addition and a three-storey rear out-rigger projection incorporating a mansard-style roof accommodating the second floor living accommodation as well as a first-floor side roof terrace.

The low height of the glazed roof conservatory and the set-back position of the outrigger from the [address] frontage meant that the architectural integrity of the 1 [name] v [name] & Carmarthenshire County Council, Energiekontor (Uk) Limited Appeal Decisions 6000386 and 6000387 main part of the original dwelling continued to be appreciated in views from [address]. In particular, the combined width and height of the outrigger meant that it did not obstruct the western-most rear elevation first and second floor windows and it also enabled the original roof form of the property to be fully appreciated in views from [address].

Extant permissions 24/0979/HOT and 25/0182/VRC result in the main dwelling being extended so that it is closer to [address], whilst still maintaining the character and architectural integrity of the original property and enabling it to still be appreciated when viewed from the side and rear, as well as from [address].

This is largely due to the unaltered width of the first and second floor elements of the rear outrigger which means that this element of the building would remain clearly subservient to the main dwelling and it would preserve views of much of the main pitched roof form and some upper floor rear elevation fenestration, enabling these features, together with the rear outrigger which is a common characteristic of housing in the area, to be fully appreciated.

Both schemes the subject of Appeal A and Appeal B would provide a small element of set-back of the resulting outrigger from the [address] frontage. However, by widening the rear outrigger to the extent proposed in both schemes, both proposals would result in a rear two-storey addition which would be of a combined height, width and scale which would be disproportionate to, and overwhelm, the main pitched roof host dwelling as well as appearing unduly large in relation to the rear elevation of the other half of the semi-detached pair.

The subsidiary rear outrigger feature would be lost due to the proposed scale of the proposals. Moreover, both appeal schemes would obscure either the majority of or all of the main building roof form and, in the case of the full width extension, the rear elevation upper floor fenestration. Moreover, in the case of the narrower Appeal B proposal, the visible rear elevation fenestration in the main house would appear incongruously small and narrow in comparison with that which prevails on the rest of the dwelling, including in relation to that proposed within the rear elevation of the extension. In the case of the latter comparison, this serves to emphasise the unduly large scale of the proposed outrigger in relation to the main dwelling.

Accordingly, I find that both appeal schemes would add an excessively large and visually over-dominant addition to the host property which would be at odds with, and overwhelm its original form, as well as resulting in a detrimental erosion of some of its defining architectural features.

There are other substantial corner properties within the locality which have benefitted from large additions comprising a variety of architectural styles. However, based on the evidence before me, none appear to be directly comparable with the appeal schemes under consideration in respect of factors including the extension designs and positions on the buildings, the character and appearance of the original properties and their juxtaposition with their street frontages. As such, these properties do not justify approval of either of the appeal schemes before me.

Given the visibility of the proposals in views from the street and neighbouring properties, there would also be material harm to the character and appearance of Appeal Decisions 6000386 and 6000387 the wider area because of the detrimental impact on one of the dwellings which makes a positive contribution to the prevailing pleasant street scene.

Whilst the [address] Conservation Area abuts the rear boundary of the site, I do not find harm to the setting and significance of the conservation area due to the intervening long back garden, outbuilding and mature vegetation between the appeal property and the rear gardens of the nearest properties within the conservation area. Also, the significance of the setting of the conservation area being surrounded by suburban residential development, some of which has been extended would not be altered.

I acknowledge the appellant’s intention to achieve a very high Passivhaus certification and the incorporation of many sustainable elements of design and measures to enhance biodiversity. However, I am not persuaded based on the evidence before, that these benefits, which are aims of other development plan policies in any case, cannot be achieved by means of either of the extant permissions.

For the above reasons, I therefore conclude that the schemes the subject of both Appeal A and Appeal B would materially harm the character and appearance of the host property and the wider surrounding area. As such they would be contrary to Local Plan Policy 28 and the supporting [name] and External Alterations Supplementary Planning Document (2015), which, amongst other things, seek to ensure that new developments improve the quality and character of buildings, spaces and the local area and that extensions do not over-dominate the building’s original scale and character.

For similar reasons, the proposals would also be contrary to Chapter 12 of the National Planning Policy Framework 2024 which seeks to achieve well-designed places.

The developments the subjects of appeals A and B conflict with the development plan taken as a whole and there are no material considerations, including the Framework, to suggest the decisions should be made other than in accordance with the development plan.

Therefore, for the reasons given above, I conclude that both Appeal A and Appeal B should be dismissed.