Appeal 3369924

The appeal is dismissed.

The main issue is the effect of the proposal upon the character and appearance of the appeal property and the wider area, including the West Kentish Town Conservation Area.

The appeal relates to a three-storey mid-terraced property along a residential street within the West Kentish Town Conservation Area (CA), a small and localised area of mid-19th century housing. The Council’s Conservation Area Statement (CAS), adopted in 2005, describes the area’s houses, which were mostly built between 1840 and 1870 in the late Georgian style, as well-detailed examples of their time which remain largely unaltered. The dwellings at Nos 2-44 (even), on the west side of [address], are recognised within the CAS as a unified terrace which makes a positive contribution to the character and appearance of the CA.

The appeal property, consistent with others along the terrace, and most others within the CA, has a traditional ‘butterfly’ or ‘M’ roof, consisting of two shallow pitches in slate meeting in a central valley running front to back, concealed behind a front parapet. The proposal is to add a flat-topped, mansard-style roof extension with windows front and rear, to create additional living accommodation within the existing loft area.

When addressing current issues, the CAS identifies roof alterations, especially mansards, as being likely to affect the character of the CA. Whilst the Council’s Home Improvements Planning Guidance (2021) recognises mansards as a common type of roof extension that can be used on Georgian or Victorian buildings, the CAS clearly states that roof extensions are unlikely to be acceptable where, amongst other things, a property forms part of a group or terrace which remains largely, but not necessarily, unimpaired, and where the roof is prominent.

The proposed mansard would be marginally set behind the dwelling’s front parapet and back from the rear wall, such that the valley and ‘butterfly’ detail would be retained. It would measure approximately 3m in total height, with around 1.2m projecting above the height of the front parapet, and with a commensurate raising of the existing chimney stacks between Nos 6 and 8.

Due to the mansard’s close proximity to the front elevation and the steep angles of its slopes, the dwelling’s increased scale and altered roof profile would be openly visible from street level along [address], and in longer distance views in the approach from the surroundings. From here it would appear as a significant and incongruous incursion along the terrace’s unbroken roof line, which is otherwise defined by the simple and uniform alignment of the parapets to individual properties.

From the rear, the visual intrusion would be even more pronounced. The rear elevation of No 8, along with a large proportion of the wider terrace, is clearly seen from [address] across some open space to the side of a three-storey block of maisonettes. From this aspect, the full height of the roof addition would be seen to rise significantly above the mostly unaltered and uniform arrangement of the roofs. Its significant bulk would resemble an additional storey; neither subordinate to the reasonably modest scale of the original dwelling, nor respectful of its architectural composition or that of the wider terrace.

I recognise the appellant’s efforts to modify the originally proposed scheme, but overall, I find that the proposed mansard-style addition would be unsympathetic to the host building and would fail to harmonise with the predominant roofline of the terrace. Notwithstanding the use of matching materials, it would represent precisely the type of development the CAS advises against, along a largely unimpaired terrace where the rear roofscape is prominent. It follows that the character and appearance of the CA would be neither preserved nor enhanced.

My attention has been drawn to some local examples where mansard-style roof alterations have taken place. I observed some of these for myself during my visit. [name] saw were amongst others along the same terrace, where degradation of its original roof profile had clearly taken place over time. In contrast, the original architectural composition of the terrace at [address] remains largely intact and uncompromised. An example at [address] demonstrated to me the harm caused to the architectural integrity of a historic terrace where such alterations occur in isolation. I do not know the planning background to any of the examples locally, but none alter my findings as they relate to the specific circumstances at the appeal property.

Having regard to paragraph 212 of the National Planning Policy Framework – December 2024 (the Framework), the harm arising from the proposal to the significance of the CA would be less than substantial. However, this does not equate to a less than substantial objection, and any harm to a designated heritage asset requires clear and convincing justification in line with paragraph 213 of the Framework. Furthermore, in line with the Framework’s paragraph 215, such harm should be weighed against the public benefits of the proposal.

Given the statutory duty set out in Section 72(1) of the Planning (Listed Buildings and Conservation Areas) Act 1990 to pay special attention to the desirability of preserving or enhancing the character or appearance of the CA, I attach significant weight to the harm that I have identified to the historic environment. I am unable to identify any public benefits to the scheme that would weigh against the harm.

Given my findings, there would be conflict with Policies D1 and D2 of the Camden Local Plan 2017. Between them, and amongst other things, these seek to ensure development displays a high quality of design that respects local context and character and preserves or enhances the character and appearance of conservation areas.

I am mindful of some support expressed locally for this kind of development to enable residents to improve their homes, but this does not alter my conclusions as they relate to the specific circumstances of this case. Therefore, for the reasons given above, the appeal is dismissed.