Appeal 6000289

The appeal is allowed and planning permission is granted for erection of a partial first floor wrap-around extension at [site address] , Twickenham [postcode] in accordance with the terms of the application, Ref 25/0038/HOT, 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 drawing nos: 01; 02; 03; 04; 05; and 06.

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

Following the submission of the appeal, the [site address] Local Plan (RLP) was adopted in October 2025. The main parties were given the opportunity to comment on the change in policy context and where these have been received the comments have been taken into consideration.

The main issues relevant to this appeal are the effect of the proposal on the character and appearance of the area; and the effect of the proposal on the living conditions of the occupiers of [address] (No. 81) with regard to light, overshadowing and outlook.

The appeal property is a semi-detached dwelling that has a two-storey side extension, a single storey rear extension and a dormer window that were, based on the submitted information, later additions. The host dwelling has a side facing gable roof whilst the side extension has a hipped roof. Based on the information before me the appeal property was subject to a hip to gable roof extension and the roof on the attached property remains hipped. The attached houses are covered with render and the dwellings along this part of [address] are generally similarly designed. The similarity in the design and scale of the semi-detached dwellings makes a positive contribution to the character and appearance of the area. The visual gaps at first floor level between properties maintains a modest level of openness in the street scene and forms part of the character of the area.

The proposal includes a hip to gable roof extension over the side extension as well as an extension at first floor level that would wrap around part of the rear of the house, and this would have a hipped roof.

The host dwelling already features a gable roof, meaning the symmetry between the two attached properties has been partially eroded at roof level. Given its limited size, the proposed hip-to-gable roof extension would not significantly alter this perception.

The wrap around extension would be slightly wider than half the width of the extended property but would only extend a modest distance beyond the rear wall. Whilst this, alongside the existing extensions and additions, would cumulatively increase the size of the property, the dwelling would not appear disproportionately larger than those in the area. When viewed within the street scene, it would also not appear significantly larger than the attached house. This is in part due to the design, siting and modest scale of the extensions and additions with the proposed roof over the wrap around extension set below the ridge of the host dwelling. Furthermore, the modest scale and siting of these extensions, including the hip to gable addition would retain the visual gap between the appeal property and the neighbouring house which is a positive feature of the area.

Although the proposal would make No. 79 appear larger at first floor level, within the street scene, the host dwelling would remain the dominant element due to the modest scale of both existing and proposed additions, most of which are positioned to the side and rear and mostly screened from public viewpoints. As a result, the combined extensions would not compromise the balanced appearance of the semi-detached pair, and the two houses would remain generally similar in design. The use of matching materials ensures the additions would remain sympathetic to the host dwelling.

Although two roof lights already exist on the front roof slope, the proposed roof lights would be limited in size and even when viewed cumulatively the roof lights would maintain an appropriate solid-to-void ratio, avoiding a cluttered appearance.

While elements of the development may diverge from the advice in the [name] and External Alterations Supplementary Planning Document (SPD), it serves as guidance rather than policy. Its purpose is to ensure extensions do not dominate the host property or undermine the character of the area and for the reasons given above the extensions would not dominate the host property and the extended property would not appear out of character in the area.

Therefore, for the reasons given above, the proposed development would not harm the character or appearance of the area. As a result, the proposal would comply with Policy 28 of the RLP which seeks, amongst other matters, for development to be of a high architectural and urban design quality and be compatible with the local character.

The SPD states that extensions would be acceptable where they do not, amongst other matters, create an unacceptable sense of enclosure and comply with Building Research Establishment (BRE) recommendations.

The proposed rear extension would project No. 79’s flank wall further along the shared boundary with No. 81 at first-floor level, although it would be set back from the boundary fence in line with the existing rear extension. No. 81 benefits from a relatively wide and deep garden that is largely open and unenclosed by development to the sides and rear given the limited height of the existing single storey extension and outbuildings at No. 79. The nearest window to the extension serves a bathroom and, although the extension would breach the BRE 45-degree line taken from this window, its obscure glazing and use mean any overshadowing from the extension’s proximity would not result in unacceptable harm to the occupiers’ living conditions.

Next to the bathroom is a utility and kitchen The submitted plans confirm that the proposed extension would not infringe the BRE 45-degree guideline from this window. Owing to the modest depth of the extension and its separation from this room, as well as from the living room located furthest away, the daylight that would reach the rear rooms in the house would not be significantly reduced. While the amount of sunlight to the rear rooms and the patio of No. 81 may be reduced, the garden would remain largely open and unenclosed by development. Based on the submitted information, any loss of sunlight would be limited to a short period of the day due to the orientation of the houses, the movement of the sun and the modest depth of the two-storey extension. For these reasons, no significantly harmful overshadowing would occur.

The nearest first-floor window serves a bedroom. Due to its distance from the proposed extension and the extension being set below the ridge height of the host dwelling, this room would not experience harmful overshadowing or a significant sense of enclosure.

The proposed extension would increase the perceived two-storey mass of the appeal property along the shared boundary with No. 81 and would be viewed in conjunction with the existing single-storey extension and outbuildings. However, its modest depth and the separation from the nearest windows mean the proposal would not create an undue sense of enclosure when viewed from the rear, particularly from the utility, kitchen, and living room. Although the dwelling would extend at first-floor level along the shared boundary, the modest scale of the extension would generally preserve an open and unenclosed outlook from the rear elevation and garden. Overall, the extension would not appear unduly overbearing, and an adequate outlook would be maintained.

Therefore, for the reasons given above, the proposal would not unacceptably harm the living conditions of the occupiers of No. 81. Consequently, the development would accord with Policy 46 of the RLP which seeks, amongst other matters, for development to not have an unacceptable impact on levels of daylight and sunlight on neighbouring properties and that adequate outlooks for neighbouring occupiers are retained avoiding any undue sense of enclosure.

Concerns have been raised regarding potential loss of privacy for the occupiers of No. 81. However, no windows are proposed within the flank wall facing their garden. While the scheme includes a bedroom window overlooking No. 81’s garden, this would replace an existing window that already provides similar views. As the new window would be positioned further along the shared boundary, the amount of the garden overlooked would be reduced compared to the current arrangement.

The proposed skylight, located within the rear roof slope, is modest in size and would offer a limited field of view, thereby restricting opportunities for overlooking the surrounding gardens. Furthermore, due to its siting, much of the garden nearest to No. 81 would be screened by the dwelling itself.

Although the introduction of additional above ground windows may increase the perception of overlooking, some degree of mutual overlooking already occurs between neighbouring properties. For the reasons outlined above, the proposal would not result in an unacceptable loss of privacy for the occupiers of No. 81 or nearby occupiers.

A Fire Statement submitted with the application identified how the development would accord with Policy D12 of the London Plan in the interests of fire safety.

The potential impact of development on privacy, residential amenity, and the character of the area, among other considerations, is assessed on a case-by-case basis. Each proposal is subject to site-specific circumstances that influence its overall effect. Therefore, granting permission in this instance would not set a precedent or prejudice the determination of future applications or appeals on nearby sites.

Further to the statutory commencement condition, a condition requiring the development to be carried out in accordance with the permitted plans is necessary in the interests of certainty. A condition requiring the materials used match the host dwelling is necessary in the interests of the character and appearance of the area.

The proposed development would be in accordance with the development plan, and the material considerations do not indicate that the appeal should be determined other than in accordance with it. Therefore, for the reasons given above, I conclude that the appeal should be allowed.