Appeal 3314387

The appeal is dismissed.

Under Article 3(1) and Schedule 2, Part 1, Class AA of the Town and Country Planning (General Permitted Development) (England) Order 2015 as amended (the GPDO), planning permission is granted for enlargement of a dwellinghouse by construction of additional storeys, subject to limitations and conditions.

The parties agree the proposal accords with the requirements set out in [name].1 in Part 1 of the GPDO so is permitted development, subject to the conditions in [name].2. On the evidence before me, I see no reason to disagree.

[name].2(3) requires the developer to apply to the local planning authority for prior approval as to the impact of the proposed development on the amenity of any adjoining premises, the external appearance of the dwellinghouse, air traffic and defence assets, and protected views, taking into account any representations received.

During my visit I also viewed the appeal site from the rear gardens of 33 and [address], and from the rear window of the first floor [address].

The National Planning Policy Framework (the Framework) was updated in December 2023, during the course of this appeal. I invited the parties to consider whether the revised Framework had relevance to this appeal and have taken account of their comments in my decision.

The Council has raised no concern with the impact of the proposed development on air traffic and defence assets or protected views. Therefore, the main issues in this appeal are: i. The effect of the proposal on the amenity, or living conditions, of adjoining premises, with particular reference to outlook, privacy and light. ii. The effect of the proposal on the external appearance of the dwellinghouse.

The appeal site is part of a small terrace, with 9 and [address] adjoining on either side. Given the modest size of the properties, the new storey would be dominant when viewed from their relatively short rear gardens. That effect would result in harm to the outlook of occupiers of those neighbouring properties.

The windows of the proposed rear bedrooms in the additional floor would directly overlook the neighbouring gardens. There is already a degree of overlooking from the first-floor bedrooms, but this is mitigated by mature planting between the houses. Overlooking is common over the gardens of neighbouring properties in terraces such as this. However, the degree of overlooking from the new windows would be significantly greater because of their additional height, and the planting would be insufficient to mitigate this. Therefore, the proposal would be detrimental to neighbouring occupiers’ privacy.

The appellant has suggested that obscured glazing for the new windows would prevent overlooking and could be secured by condition. The suggested condition would be reasonably related to the amenity of adjoining premises, in accordance with [name].3(15) of the GPDO. However, the bedrooms in question would be principal habitable rooms with no secondary aspect, so obscured glazing would unreasonably restrict the outlook of future occupiers. I therefore find the proposed condition would not meet the test of reasonableness in paragraph 56 of the Framework.

Bearing in mind the orientation of the terrace, the additional storey would not have a material effect on natural light to the habitable rooms or gardens of 9 and [address]. Consequently, there would be no harm to neighbouring occupiers’ light.

[address] is perpendicular to [address]. Although 33 and [address] do not abut the appeal site, they are adjoining in the sense of being nearby or neighbouring. The additional storey would not be close enough to have a material effect on natural light to the flats in these premises. Nevertheless, the side elevation of the extra floor would be very prominent when viewed from rear windows in the upper floors of both buildings, and from the rear garden of No 33. It would dominate the visible roofscape, with an overbearing effect on the outlook of the flats’ occupiers.

There is no requirement to have regard to the development plan as there would be for any development requiring planning permission. Nevertheless, Policies CC2 and SC7 of the Hounslow Local Plan (HLP) are material considerations and seek to minimise overbearing and direct overlooking of adjoining dwellings. The Framework is also a material consideration and seeks a high standard of amenity for existing occupiers, which includes occupiers of neighbouring dwellings. Insofar as they are material considerations, these policies would not be satisfied by the proposal for the reasons given.

For the above reasons, I conclude the proposal would have a harmful effect on the amenity of adjoining premises with particular reference to outlook and privacy but would not have a harmful effect with reference to light.

The appeal premises is a compact, two-storey dwelling of modern appearance. On its principal elevation, the ground floor has a brick finish and is slightly set back from the first floor, which is set within a mansard roof of grey tiles with semi-dormer windows. The ground and first floors have similar dimensions, despite their contrasting materials. They therefore read as complementary halves, giving a strong sense of balance and proportion to the appearance of the dwelling. There is a similar design on the rear elevation.

The proposed additional storey would be finished in grey tiles to match those covering the existing first floor and roof of the house. It would also include windows of similar design and alignment to those in the existing dwelling. In addition, it would be subordinate in size relative to the existing house. However, the gently sloping façade of the first floor would be replaced by a stepped, vertical façade. What would become the middle floor would protrude from the elevations of the building, with the upper floor set back above it. Above this, the roof would appear as a clearly separate element, notwithstanding that its pitch would be similar to the existing one.

This configuration would disrupt the balance between the dwelling’s complementary horizontal halves, causing it to appear top-heavy and out of proportion. The impression of a storey within the roof would also be lost. The proposal would appear incongruous and detract from the integrity of the original building’s design, on both the front and rear elevations.

The appeal premises is part of a terrace within a small estate of similar terraces. The highly consistent appearance of the houses in the estate makes a positive contribution to the appearance of [address] as a whole. The appeal proposal would add a storey in the middle of an otherwise uniform terraced roofscape. This would look highly incongruous, to the detriment of the appearance of the surrounding area.

I have considered the appellant’s argument that the condition in paragraph AA.2(3)(a)(ii) of the GPDO restricts consideration of external appearance to the effect on the dwellinghouse to be extended and does not include the effect on the surrounding area. The appellant supports this argument by reference to two appeal decisions. One of these1 concerns an application for prior approval under Schedule 2, Part 20, Class A of the GPDO, so is not directly comparable. As regards the other2, even if I were to accept that Inspector’s interpretation of 1 reference APP/T1410/W/20/3263486 2 reference APP/J1535/D/21/3266264 the condition, this would not overcome the harm to the existing dwelling house I have found.

Policies CC1, CC2 and SC7 of the HLP require careful consideration of external appearance, including composition and arrangement, and expect extensions to complement the original building and respond to the wider context. The Framework seeks development that is visually attractive as a result of good architecture and that is sympathetic to local character including the surrounding built environment. Insofar as they are material considerations, the aims of these policies would not be met by the proposal for the reasons given above. Furthermore, the Framework’s support for mansard roof extensions applies to suitable properties where their external appearance harmonises with the original building, which would not be the case in this instance, for the reasons given.

Taking all this together, I conclude the proposal would have a harmful effect on the appearance of the dwellinghouse.

I acknowledge the additional storey would create additional living accommodation for the occupants of [site address] . However, this is outside the scope of matters that can be considered in this case.

I note the correspondence between the appellant and the Council, but the Council’s decision-making processes are outside my remit in determining this appeal. I have considered the appeal on its merits.

For the reasons given above, I conclude the appeal should be dismissed.