Appeal 3366730

The appeal is allowed and planning permission is granted for erection of a part single storey, part two storey extension to the side and rear together with the conversion of roof space to habitable use to include a rear dormer, 3 front roof lights and conversion of roof from hip to gable end at [site address] in accordance with the terms of the application, Ref 34822/APP/2025/142, subject to the following conditions:

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

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

The development hereby permitted shall be carried out in accordance with the following approved plans: 6121-25-204 (Existing Block Plan), 6121-25- 205 A (Proposed Block Plan), 6121-25-203 A ([name] Extension), 6121-25-202 A ([name] and [name]), and Location Plan.

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.

I have used the Council’s description of the development in reaching my decision as it more fully describes the details of the development than that given on the original planning application form. The appellants appeal form also makes reference to the updated description.

I note from the evidence before me that the hip to gable and dormer roof extensions, together with the front roof lights have an extant Certificate of Lawful Development (CLD) (Ref. 34822/APP/2024/3092). Therefore, these elements have deemed planning permission under the General Permitted Development Order (2015) and as such can be carried out without the grant of express planning permission. In any case, the Council’s main concerns relate to the proposed two storey side extension, alongside the roof alterations granted under the CLD, which have as such been the focus within this appeal.

The main issue is the effect of the proposed development on the character and appearance of the host dwelling and area.

The appeal site comprises of a two-storey semi-detached dwelling sited on a prominent corner plot between [address] and [address] which is particularly visible from the east end of [address]. There is an established urban layout of the area of mainly two-storey semi-detached and terraced dwellings. Corner plots, such as the appeal site, benefit from larger plot sizes with more open space and building gaps afforded through this.

The proposed development would introduce a two storey side extension, which would be over half the width of the original dwelling. It would be set back from the front elevation and notably set down from the roof ridge, therefore in height and depth terms, would be physically smaller than the host dwelling. The cumulation of the proposed development’s bulk and use of matching materials and architectural features found on the host dwelling, would mean that it would appear as a subordinate addition, retaining the established hierarchy on site. Further, the clear distinguishment between the host dwelling and the side extension in terms of its subordinance, means the proposed development would not result in a terracing effect.

The plot size and shape of the appeal site means that the proposed development’s width and depth would allow for the continued legibility of the front building line of No. 136 (and further dwellings) when viewed from the eastern end of [address] by maintaining a visual break between the side elevation of the appeal dwelling and the boundary. Furthermore, its footprint in relation to the overall plot size, which would appear to be modest, would maintain the established urban grain of the area, and with specific regard to corner plot dwellings.

[name] acknowledge that the proposed development would not comply with the specific technicalities of subsection C(i) of policy DMHD1 (Alterations and Extensions to [name]), which sets out that side extensions should not exceed half the width of the original dwellinghouse, I do consider that the proposed extension would not have an adverse impact on the host property, wider area or street scene in terms of character and appearance. Consequently, the proposed development would comply with the overarching objectives of the policy which, amongst other things, aims to ensure that extensions to residential dwellings are appropriate to the local context and are subordinate to the host dwelling.

For the reasons above, I find that the proposed extension would not conflict with policy BE1 ([name]) of the Hillingdon Local Plan: [name] - [name] (2012), or policies DMHB11 (Design of New Development), DMHB12 (Streets and Public Realm) of the Hillingdon Local Plan: [name] - Development Management Policies (2020) which, together and amongst other things, aims to ensure development is well integrated with the surrounding area and harmonises with the local context. For the above reasons, I further find that the proposed extension would not conflict with policy DMHD1 (Alterations and Extensions to [name]) of the Hillingdon Local Plan: [name] - Development Management Policies (2020)

When considering the cumulative effect of the side extension together with the roof alterations, I do acknowledge that that the overall development would represent a substantial additional bulk to the appeal dwelling. However, given that the side extension and roof alterations would be acceptable in themselves, no harm would directly arise from the cumulative impact by me allowing this appeal.

A condition is required to ensure that the development accords with the statutory requirement that development starts no later than three years from the date of this decision. A condition is also required to ensure that development is carried out in accordance with the submitted plans, for certainty and in the interests of enforcement. In the interests of ensuring that the impact of development to the character and appearance of the host dwelling and wider area is acceptable, a condition is required which ensures that the proposed development is constructed in materials which match those of the host dwelling.

For the reasons given above and having had regard to all other matters raised, I recommend that the appeal should be allowed.

I have considered all the submitted evidence and my representative’s report and on that basis the appeal is allowed.