55 Avondale Road, Mortlake, SW14 8PU

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision Site visit made on 19 September 2025 by O Tresise MSc MA MRTPI an Inspector appointed by the Secretary of State Decision date: 02 December 2025 Appeal Ref: APP/L5810/W/25/3361126 55 Avondale Road, Mortlake, Richmond Upon Thames SW14 8PU • 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 Mr Jonathan Lines against the decision of London Borough Council of Richmond Upon Thames • The application Ref is 24/2414/FUL. • The proposed development is described as ‘Extension of existing rear dormer over part of the rear outrigger with 1 no roof light in flat roof’. Decision 1. The appeal is dismissed. Preliminary Matter 2. The Council’s Decision Notice and Officer Report quote policies of the London Borough of Richmond upon Thames Local Plan which was adopted in July 2018. However, the policies have been superseded by the Richmond upon Thames Local Plan ‘The best for our borough’ (2024 to 2039) (the Local Plan) which was adopted during the course of the appeal process and now forms part of the statutory development plan for the area.

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision The main parties were able to comment on the policy of the Local Plan that would be relevant, and I have based my decision on the policy rather than those which were originally quoted in the Decision Notice. Main Issue 3. The main issue is the effect of the proposed development on the character and appearance of the area. Reasons 4. Avondale Road, with the exception of a block of residential properties located opposite the application site, and the surrounding area are primarily comprised of two-storey terraced houses. Many of these properties, including the appeal site, feature two storey outriggers at the rear. 5. At my site visit, I observed a variety of roof extensions at the rear of properties in the area; however their original architectural features largely remain intact. The general uniformity of the buildings also contributes to a consistent and cohesive character within the area. 6. The London Borough of Richmond Upon Thames Local Plan Supplementary Planning Document - House Extensions and External Alterations May 2015 (SPD) https://www.gov.uk/planning-inspectorate

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision Appeal Decision APP/L5810/W/25/3361126 advises that roof extensions should be kept in scale with the existing structure and should not dominate the original roof. It further recommends that a significant portion of the existing roof should remain visible beneath any new dormer. 7. The proposed roof extension would be positioned at the corner of the existing roof planes at the rear. Whilst the proposed extension would not project beyond the suggested outrigger midpoint, it would not be modest in scale. In particular, it would extend close to the eaves of the main building. As such, it would create a bulky and visually overbearing feature that would detract from the prevailing character of the area. 8. Whilst the appellant contends that the proposed mansard roof may be less dominant, it would introduce a new roof form that is not a typical architectural feature in the area. Consequently, the proposal would result in an incongruous addition that would diminish the character and appearance of the building and its surroundings. 9.

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision The appellant has drawn my attention to a number of properties on Avondale Road, Ashleigh Road, First Avenue, Second Avenue and Cowley Road that benefit from planning permission or lawful development certificates for loft dormers extending over the outrigger or for L-shaped dormers. 10. Whilst these roads are within the West of White Hart Lane Character Area, the properties along each road appear to represent different architectural characters. As such, properties on First Avenue feature two-storey flat-roof outriggers at the rear, while those on Second Avenue have two-storey pitched-roof outriggers. Cowley Road is situated within a conservation area and exhibits a distinctive heritage character. Notwithstanding these, these properties are not seen within the same context and some of them, including 37 Avondale Road, were determined prior to the adoption of the SPD. 11. The appellant’s submission includes photographs of two rear roof extensions on 54 and 62 Ashleigh Road, located opposite the appeal site. However, the design of these roof extensions differs from the appeal proposal. One extension is set back from the eaves of its main building, while the other features a low pitched-roof dormer. 12.

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision With regard to the roof extension at 3 and 29 Ashleigh Road, the appellant’s submission shows that their roof extensions are noticeably set down from the main ridge, and their designs also differ from the appeal proposal, which would introduce a new roof form. With regard to the roof extension at 118 Ashleigh Road, whilst the dormer over the outrigger may be the same height as the main dormer, it has a low-pitched roof, which is also differ from the appeal proposal. 13. I therefore find that none of these examples are directly comparable to the appeal proposal which I have, in any event, considered on its own planning merits. As such, they do not attract material weight. 14. I therefore conclude that the proposal would result in harm to the character and appearance of the host building and the surrounding area. Therefore, it would conflict with Policy 28 of the London Borough Richmond Upon Thames Local Plan 2024-2039, and that requires all development to be of high architectural quality, respects, contributes and enhances the local environment and character of the area. https://www.gov.uk/planning-inspectorate 2

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — Appeal Decision Appeal Decision APP/L5810/W/25/3361126 Conclusion 15. The proposed development conflicts with the development plan and there are no material considerations to indicate that the decision should be taken otherwise than in accordance with it. Therefore, the appeal is dismissed.

55 Avondale Road, Mortlake, SW14 8PU — Richmond Upon Thames London Borough Council — O Tresise INSPECTOR https://www.gov.uk/planning-inspectorate 3