Appeal 3366894

The appeal is allowed and planning permission is granted for a full width roof extension at [site address] in accordance with the terms of the application, Ref. 24/07302/FULL, 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: PL_001; PL_002; PL_004; PL_014; PL_026; PL_101; PL_102; PL_114; PL_025; LOCATION PLAN.

The proposed new rooflights will be conservation style.

The roof extension shall be clad in lead on the principal front and rear roof pitches.

Prior to works commencing on the front and rear windows and doors, elevation and sectional drawings at a minimum scale of 1:20 shall be submitted to and approved by the local planning authority. Works shall proceed in accordance with the approved drawings.

Notwithstanding the description of development set out above, which reflects the wording used in the application form, it is clear from the submitted plans and supporting documents that the development comprises a full width roof extension Accordingly, the reference to the replacement of an existing partial-width extension at roof level does not form part of the formal description of development.

The main issue is whether the development would preserve or enhance the character or appearance of the St John’s Wood Conservation Area.

The appeal relates to No. [site address] , located within the St John’s Wood Conservation Area. The property occupies an infill plot between two substantial detached villas and contributes to the architectural rhythm and continuity of this formally laid-out, tree-lined boulevard. While not statutorily listed, No. 42 is identified in the Conservation Area Audit as an Unlisted Building of Merit, indicating that it makes a positive contribution to the character and appearance of the area.

Although the building is identified as an Unlisted Building of Merit, the Conservation Area Audit (Audit) does not provide a specific justification for this designation. It notes that all unlisted buildings dating from the early to mid-Victorian period are considered to contribute positively to the Conservation Area, including more modest mews and terraces. It also acknowledges that some buildings retain this status despite unsympathetic alterations. In this context, the designation appears to reflect the building’s age, scale, and contribution to the broader townscape, rather than any particular architectural distinction or intactness.

[address] is noted in the Audit for its wide layout and generous plot sizes, contributing to a formal and spacious streetscape. The architectural character is varied but cohesive, with buildings typically exhibiting classical detailing such as bracketed eaves, stucco façades, and low-pitched slate roofs. Mature trees and front garden planting are identified as key components of the townscape, softening the built form and contributing to the area’s distinctive character.

The Audit identifies the roofscape as a key component of the townscape, contributing to visual coherence and architectural character. In many cases, this comprises parapet-concealed profiles, discreet dormers, and mansard-style additions that respect the symmetry and scale of the original buildings. Unsympathetic roof extensions are highlighted as negative features, particularly where they disrupt architectural rhythm or introduce visual clutter.

The existing partial-width roof extension at No. 42 is visually and architecturally discordant. It interrupts the symmetry of the building and detracts from the integrity of the roofline, an important feature of the conservation area. As noted in the Audit, such extensions contribute to visual clutter and erode local character. The current addition is identified as a negative feature in this context.

The proposed full-width roof extension would replace the discordant existing half-width addition with a more coherent and proportionate form. Like the current extension, it would be set back behind the existing parapet, thereby preserving the integrity of the principal elevation. However, unlike the existing addition, the proposed design restores balance to the roofline and respects the building’s architectural character. While zinc is proposed, lead is considered more appropriate in this context and should be secured by condition. Lead is a traditional material found throughout the Conservation Area and its use would better reflect the Council’s concerns regarding material compatibility, supporting visual continuity and reinforcing local character.

While the Council has raised concerns regarding potential dominance, the proposed extension is modest in scale and well-integrated with the host building. It reflects the established typology of roof alterations in the area, characterised by set-back profiles, restrained massing, and contributes to visual continuity. Its design respects the architectural rhythm of [address] and avoids the visual clutter cautioned against in the Audit.

The extension would remain largely concealed from public vantage points due to its set-back position behind the parapet. The design restores balance to the roofline, reinforcing the architectural rhythm of [address]. By spanning the full width and adopting traditional materials, it complements the surrounding roofscape and avoids the visual fragmentation caused by the current extension. This contributes positively to the townscape and aligns with the Audit’s guidance on preserving roofscape character.

The proposal therefore accords with the statutory duty under Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990, which requires special attention to be paid to the desirability of preserving or enhancing the character or appearance of conservation areas. In this case, the proposal preserves the character and appearance.

It also complies with Policy 39 of the Westminster City Plan 2019–2040, which seeks to protect heritage assets and ensure that development within conservation areas conserves their significance. Furthermore, it aligns with Policies 38 and 40, which promote high-quality design and contextual responsiveness.

In national policy terms, the proposal complies with Section 16 of the National Planning Policy Framework (December 2024). Paragraphs 202 and 203 highlight the importance of conserving heritage assets in a manner appropriate to their significance, and support development that conserves or enhances their contribution to local character.

The proposed extension replaces a discordant and visually fragmented element with a restrained, full-width form that better reflects the architectural language of the conservation area. It respects the building’s scale and rhythm, and, subject to a planning condition securing the use of lead, employs materials appropriate to the local context. The extension avoids harm to public views and, as such, preserves the character and appearance of the St John’s Wood Conservation Area while enhancing the building’s contribution to the townscape.

In imposing the conditions, I have had regard to the tests for planning conditions in paragraph 57 of the Framework and the guidance in the Planning Practice Guidance. In this respect there is a need for a condition listing the plans to which the proposal should accord, in the interests of certainty.

The Council suggested a condition requiring the external surfaces of the development, excluding rooflights and roof extension cladding, to be constructed in the materials shown on plan no. PL_102. However, this requirement is already secured through the approved plans, which clearly specify the materials to be used. As the condition would simply duplicate information already controlled by the approved drawings, I do not consider it necessary to include it in the decision.

Zinc cladding, while visually recessive, is not characteristic of [address]. A lead finish is therefore required to maintain roofscape consistency. Revised fenestration details will ensure architectural coherence. These conditions align with policies 38, 39 and 40 of the City Plan.

To ensure the detailed design of the proposed windows and doors respects the architectural character of the host building and the surrounding conservation area, I agree with the Council that drawings at a scale of 1:20 are necessary and should be submitted for approval. This will allow for thorough assessment of proportions, profiles, and detailing, elements that are crucial to preserving visual harmony and heritage significance. This condition aligns with policies 38, 39 and 40 of the City Plan.

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