Two storey side extension following demolition of detached garage

Appeal Decision Site visit made on 28 July 2026 by J Davis BSc (Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 6 August 2026 Appeal Ref: 6010316 7 Saxonbury Avenue, Sunbury-on-Thames, Surrey, TW16 5EY • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Benjamin and Lauren Jacob against the decision of Spelthorne Borough Council. • The application Ref is 26/00060/HOU. • The development proposed is two storey side extension following demolition of detached garage. Single storey rear. Decision 1. The appeal is dismissed. Preliminary Matter 2. The Council has advised that since the determination of the planning application the Spelthorne Local Plan 2024-2039/40 (SLP) and Spelthorne Design Code (SDC) were adopted on 17 March 2026. The newly adopted local plan replaces all of the saved policies of the Spelthorne Development Plan Core Strategy and Policies Development Plan Document 2009. I am advised that the relevant policy applicable to the appeal proposal is Policy PS2: Designing places and spaces. The appellant has been made aware of this and has had a chance to comment. It is incumbent on me to take into account the most relevant and up to date information in reaching a decision and I have therefore dealt with the appeal on this basis. Main Issue 3. The main issue is the effect of the proposed development on the character and appearance of the area. Reasons 4. The appeal concerns a two-storey dwelling with a single storey garage on its southern side. Saxonbury Avenue contains a variety of housing types and designs however the appeal property is located within a row of seven houses (1-13 odd) that are of a similar design and appearance. These dwellings have a staggered siting in relation to the highway, so that their southern flank elevations are particularly prominent in the street scene. Each dwelling has a prominent front gable, separated from the neighbouring dwelling by a single storey garage resulting in a regular rhythm. Whilst some of the dwellings have been altered at ground floor Appeal Decision 6010316 2 level, the small gaps above the garages contribute towards the spacious character and appearance of this part of Saxonbury Avenue. 5. Policy PS2 of the SLP states that the Council will require a high standard in the design and layout of new development. Amongst other things, development should respect and make a positive contribution to the street scene and the character of the area in which they are situated and pay regard to the scale, height, proportions, building lines, layout, materials and other characteristics of adjoining buildings and land. Regard should also be had to the National Model Design Code and any design policies and codes which are produced. 6. The Council has produced the Spelthorne Design Code (2025) (SDC) which whilst non-statutory, provides useful design guidance for residential extensions (amongst other developments). It advises in the case of semi-detached properties and detached buildings which are symmetrical or the gaps between buildings are limited, an extension should normally be designed to be subordinate to the host dwelling, which can be achieved by an appropriate ‘set-back’ and ‘set-in’. This is, in part, to ensure that a ‘terracing effect’ does not occur. 7. In this regard, the SDC advises that a two-storey side extension should be ‘set-in’ from the boundary by a minimum 1 metre and that it should be ‘set-back’ at least 1 metre, unless a lesser distance can be justified. 8. The proposed two storey side extension would be set in from the side boundary with No 5 Saxonbury Avenue by about 1 metre. Whilst this distance would not be achieved in respect of the overhanging eaves, the gap would nonetheless contribute towards ensuring that a ‘terracing effect’ would be avoided. 9. However, the extension would sit flush with the host dwelling’s front elevation. Despite its lower ridge height and part-hipped roof, it would not appear sufficiently subordinate and would visually compete with, and detract from, the front gable, a distinctive feature of both the appeal property and the row of houses in which it sits. This would be especially noticeable from the south, where the set-in from the side boundary would be less apparent because the front elevation of the extension would lack a meaningful set-back. Overall, the extension would not appear suitably subservient to the host dwelling and would disrupt the spacious pattern and rhythm of development along this part of Saxonbury Avenue, harming the character and appearance of the area. 10. I accept that non-statutory design guidance may sometimes be applied flexibly, depending on the merits of a particular proposal. The appellant has referred to local examples, including at 29 Saxonbury Avenue, where appeal Inspectors have applied the Council’s previous Supplementary Planning Document - Design of Residential Extensions and New Residential Development (2011), flexibly. However, although I have not been given full details of all these examples, most do not appear directly comparable with the appeal proposal, which sits within a very uniform row of houses. In any event, I must determine the appeal on its own merits. 11. The Council also raise concern regarding the crown roof design of the proposed two storey extension. However, the flat roof section would be limited in its extent, and the side pitch of the roof would respect that of the main roof slope such that I do not share the Council’s concerns in this regard. The proposed single storey rear extension would be of an appropriate design, and I have no reason to disagree with the Council’s assessment of this aspect of the proposal. Appeal Decision 6010316 3 12. I acknowledge the proposal would provide improved living accommodation for the occupiers of the dwelling, allowing it to better meet modern needs. However, this consideration does not outweigh the harm that would be caused to the character and appearance of the area. 13. I therefore conclude that the proposal development would have a harmful effect on the character and appearance of the area. It would be contrary to the high-quality design objectives of Policy PS2 of the SLP and the National Planning Policy Framework 2024 and would conflict with the guidance set out in the Council’s design code. Conclusion 14. The proposal is contrary to the development plan as a whole and there are no other material considerations of sufficient weight to indicate a decision should be made other than in accordance with the development plan. I therefore conclude that the appeal should be dismissed. J Davis INSPECTOR