Appeal 6006622

The appeal is allowed and planning permission is granted for the erection of a single storey rear extension with a pitched roof and four roof windows at [site address] in accordance with the terms of the application, [name]/2026/0001, subject to the following conditions:

The development hereby permitted shall begin not later than 3 years from the date of this decision.

The development hereby permitted shall be carried out in accordance with the following approved plans: P01, P02, P03 and P04.

The materials to be used in the construction of the exterior surfaces of the development hereby permitted shall match those used in the existing building.

There are two main issues. Firstly, the effect of the proposed extension on the character and appearance of the host dwelling, the adjoining terrace and the surrounding area; and secondly, the effect on the living conditions of neighbouring occupiers at Nos 12 and [address] with respect to outlook, light or sense of enclosure.

The appeal dwelling is a mid-terraced house in a short terrace of four houses. It lies in a quiet, residential street of mostly similar short terraces. The house has a relatively short garden with an angled rear boundary, owing to the line of a cul-de-sac to the rear. The proposed extension would occupy the width of the rear elevation and would project some 3.6m from it. The roof would be pitched and Appeal Decision Ref: 6006622 finish below the cills of the first floor windows, with a maximum height of some 3.3m. The eaves would have a height of about 2.3m.

The Hounslow Character, Sustainability and [name] – Part A5 [name] (SPD) 2024, states that the depth of a single storey rear extension normally considered acceptable for terraced properties is 3.05m. The Council considers that, owing to the proposed extension exceeding this and having a footprint of about 50% that of the main dwelling, it would appear bulky and disproportionate, and fail to be subservient to the host building.

However, the single storey extension with its shallow pitched roof would clearly appear subservient to the larger and taller two storey dwelling. Moreover, although deeper than the guideline set out in the SPD, the proposed extension would be noticeably wider than it was deep, resulting in a proportionate appearance that would sit comfortably to the rear of the dwelling and the terrace as a whole. I note the Council’s concern regarding the size of the garden. Nevertheless, the proposed extension would not overwhelm the space, and a sufficient area would be retained to provide an adequate outside amenity area for the occupiers of the dwelling.

It is concluded on the first main issue that the proposed extension would have no materially detrimental effect on the character or appearance of the host dwelling, the adjoining terrace or the surrounding area. In consequence, it would comply with Policies CC1, CC2 and SC7 of the Council’s Local Plan, 2015-2030 (LP), adopted

Taken together and amongst other things, these expect new development to achieve high quality urban design that responds to its context and local character and, in the case of residential additions, compliments and harmonises with the building and surrounding area. Extensions should have regard to the quality, character, materials and scale of the principal building, be subordinate to it and not over develop the site in terms of mass and density.

Turning to the living conditions of neighbouring occupiers, neither No 12 nor No 16 have conventional rear extensions. Nevertheless, No 12, which is the adjoining mid-terrace property, has a wooden shelter/pergola adjoining the rear of the dwelling and close to the shared boundary. This projects noticeably above the boundary fence and appears to be about 3m in depth. It has a solid side elevation facing the boundary which blocks views from the ground floor windows in the rear of No 12 towards the rear garden of the appeal dwelling. Although the structure is built of wood it is of sturdy construction and appears to be well established. I have no reason to believe it is intended to be temporary. The Council’s SPD states in paragraph A519 that a pergola on the back of a house is still considered to be an extension.

The wooden structure has the same effect on outlook from No 12 towards the appeal dwelling as an extension of similar depth. The SPD makes clear that where a property lies next to one with an existing extension, a similar extension may be permitted if it does not cause an unacceptable sense of enclosure or block light to the neighbour. The wooden structure, owing to its scale and solid side elevation, would prevent any material sense of enclosure or blocking of light from the proposed extension. Therefore, and notwithstanding that the extension may be somewhat deeper, since it would comply with the objectives of the SPD, I find its effect on No 12 would be acceptable. Appeal Decision Ref: 6006622

With regard to No 16, this is an end terrace house on a wider plot. It has a single storey side extension. Owing to its end of terrace position, its relationship with the appeal dwelling is akin to that of a semi-detached house. Whilst the SPD makes clear that its guidelines apply equally to extensions on end of terrace dwellings (which by definition have mid- terraced adjoining neighbours), in this case, the wider plot and more open aspect to the side of No 16 is relevant in assessing the effect of the proposed extension on the living conditions of its occupiers. Of further relevance is the Council’s own standard, set out in the SPD, for single storey rear extensions on semi-detached dwellings which is 3.65m.

The proposed extension would be clearly visible from rear windows and from the garden at No 16. Nevertheless, its limited height, reducing to low eaves, depth which would comply with the SPD standard for a semi-detached dwelling, and the open aspect at No 16 to the rear and opposite side above the boundary fence, would ensure that there was no unacceptable sense of enclosure. In terms of light, the north-facing rear of the dwellings, coupled with the moderate scale of the proposed extension and its relationship with No 16 would prevent any material loss of daylight or sunlight.

It is concluded on the second main issue that the proposed extension would have no materially detrimental effect on the living conditions of neighbouring occupiers at Nos 12 and [address] with respect to outlook, light or a sense of enclosure. In consequence, it would comply with Policies CC1, CC2 and SC7 of the LP. In particular, the requirement set out in Policy SC7 to minimise harm to neighbouring residents and future occupiers (by avoiding an unacceptable loss of daylight/sunlight, outlook or by creating an unacceptable sense of enclosure) through high quality design would be met.

Although there would be a tension between the proposed extension and the depth restriction set out in the SPD, as reasoned above, I find that the inconsistency would not cause any material detriment or result in a conflict in terms of policy objectives regarding either character and appearance or the living conditions of neighbouring occupiers. Moreover, guidance is intended to set a benchmark against which each case may be judged on its own merits, which is what I have done. In this case I find that the normal depth limit set out in the SPD may be set aside.

Turning to conditions, in addition to the statutory commencement condition I consider that a condition requiring the development to be carried out in accordance with the approved plans and in materials that match the host dwelling would be necessary. This is to ensure certainty and consistency and to protect the character and appearance of the dwelling, the adjoining terrace and the street scene of [address]. The Council does not suggest any further conditions, and I agree none would be necessary.

For the reasons set out above and having regard to all other matters raised, I conclude that the appeal should be allowed.