Appeal 3304040

The appeal is dismissed.

The main issue is whether the proposal would preserve or enhance the character or appearance of the [address]/[address] Conservation Area.

The appeal site is located within the [address]/[address] Conservation Area (CA). In carrying out planning functions, the statutory test in relation to Conservation Areas is that special attention shall be paid to the desirability of preserving or enhancing the character or appearance of the Conservation Area.

The CA covers a predominantly residential area and is characterised by late Georgian and early Victorian terraces which have an architectural consistency, homogeneity, and historic interest. This gives a high quality and attractive built environment. Given the above, I find that the significance of the CA, insofar as it relates to this appeal, to be primarily associated with the architectural unity of building form and detailing of properties on [address] which has both architectural and historic interest.

The appeal property is located towards the southern end of [address] and shares similar symmetry and architectural features with other properties along these long terraces. It is notable that when viewed from the street at the front, the roofs are largely concealed by parapet walls. However, to the rear, viewed predominantly from private gardens and nearby buildings, the rhythmical roof outlines and distinctive butterfly roof parapet detail along the terrace is a characteristic and distinctive feature. The appeal building, in line with other buildings on the street, makes a positive contribution to the character and appearance of the CA.

The appeal proposal seeks to erect a mansard roof extension which would almost entirely fill in and extend upwards the V-shaped butterfly roof to create a bedroom and bathroom. It would be set back from the existing front parapet wall and to the rear would be set back slightly and sloped in form, featuring a dormer window and rooflight. It would have a flat roof with the sides finished in slate. The proposal would replace a much smaller extension to the roof which provides a single room and rises directly off the rear walling interrupting the roof parapet detail.

[address]/[address] Conservation Area Design Guidelines 2002 (CADG) provides guidance on roof extensions. The appeal property is not identified in this guidance as a building where a roof extension would be permitted. Further to this, paragraph 3.14 advises that roof extensions will not be permitted which are visible from the street or public area, including long views from side streets.

Paragraph 3.15 of the CADG highlights that the roofline is an important part of the character of a terrace, and many terraces in the CA feature valley roofs hidden behind front parapet walls. It also advises that constructing roof extensions which are not in keeping with a terrace can be damaging to architectural unity, and have a harmful effect on the character and appearance of the CA. In addition, the [name] (UDG) states that where there is an unbroken roofline within a CA then roof extensions will not generally be acceptable as it would be harmful to the character of the terrace.

The proposed plan section and 3D line drawings suggest that the roof extension would not be visible from [address] or [address]. The 3D drawings have been prepared using check measures and [name] but there is no further detail to explain this. I agree that the proposed front extension would not be conspicuous in close views along [address], but from what I have seen on site and the evidence before me I am not convinced that it would be completely invisible from the junction with [address], given the ability to view chimneys behind the parapets on some buildings in the street. Given the importance of the roofscape to the character and appearance of the area and clear roof design guidance in the CADG and [name] must therefore take a cautious approach in this assessment and consider that it would be visible, albeit only to a limited extent. It has, therefore, the potential to marginally disrupt the unified unbroken roofline.

The front roof extension on [address], opposite the appeal site, does not appear to be visible from the street. However, I have no details of this structure, including its degree of set back from the front parapet and I am therefore unable to draw any comparisons between this and the appeal proposal. Likewise, I have few details of the roof extensions on [address] but note that some are visible in the streetscene and properties along [address] have a more varied and disrupted roofline in contrast to the more unified frontage to properties in the vicinity of the appeal property on [address].

To the rear, the appeal proposal would be clearly viewed from nearby gardens and from the rear of houses on [address] which face the appeal property, especially views from upper floors. [name] recognise that the existing small roof extension slightly disrupts the existing rhythm of butterfly roofs along the terrace and disrupts the parapet detail, this small extension is an anomaly in a significant row of unaltered roof forms. Its matching brickwork which rises off the back wall also helps minimise its visual impact. The impact of the proposed development would be considerably greater because of its size, location and form. It would extend across practically the whole width of the roof and be of a similar height to the chimneys. Although the butterfly parapet would be reinstated, the extension would sit only just behind and would be viewed as a discordant and dominant element, interfering with the regular form and rhythm of the unaltered rooflines which are such a distinctive feature of this terrace. It would result in the loss of the V roof profile and introduce a boxy addition which would have a far greater visual impact than the existing small addition, and harm the integrity of the terrace as a whole.

I note that the UDG includes an example of a roof extension set behind a butterfly parapet profile. However, this is not going to be an acceptable solution in all situations and the guidance recognises that proposals for roof extensions anywhere along an unaltered roofline within a CA will generally not be acceptable. Further, that where a roofline is broken, an assessment would need to be made of the extent to which the unity and consistency of the roofline has already been compromised. In the case of the appeal before me, except for the small extension on the host building, the roofline is unbroken for a considerable stretch, and it has been recognised that this contributes positively to the character and appearance of the area.

I acknowledge that the views of the rear elevation would be private, but the collective views would be extensive and of considerable importance, and private views alone would not diminish the harm that would occur. Furthermore, at appeal, a similar form of development in the street was dismissed in 2016 which demonstrates the Council’s commitment to protecting the character and appearance of the roofscape.

[address] the building form and architectural detailing of properties is much more varied than on [address] and this is also reflected in significant variations to the roofline. Consequently, the circumstances along [address] are materially different to the regular form and rhythm of the roofs on [address] and offer no support to this proposal.

The proposal would therefore fail to preserve or enhance the character or appearance of the [address]/[address] CA. In my judgment, it would cause less than substantial harm to the CA, a designated heritage asset, contrary to the expectations of section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 which requires that special attention should be paid to the desirability of preserving or enhancing the character or appearance of the Conservation Area.

Under paragraph 202 of the National Planning Policy Framework (the Framework) this harm should be weighed against any public benefits of the proposal, including, where appropriate, securing the asset’s optimum viable use. The provision of additional living space would be a private benefit. Public benefits would be derived from reinstating the rear parapet detail, although this would have to be balanced against the greater harm in my view of the proposal itself. The proposal also has the potential to maximise the family accommodation and range of accommodation available, but this would be a limited benefit. Therefore, there are insufficient public benefits to outweigh the less than substantial harm that I have identified, giving considerable weight and importance to paying special attention to the desirability of preserving or enhancing the character or appearance of the CA. Accordingly, the proposal would conflict with the Framework and Policy CS9 of [name] (2011); Policies DM2.1 and Policy DM2.3 of Islington’s Local Plan: Development Management Policies (2013), the CADG and UDG. Policy DM2.3 and the Framework require heritage assets to be conserved and enhanced in a manner appropriate to their significance.

For the reasons given above, the proposal would conflict with the development plan, when read as a whole. Material considerations, including the Framework, do not indicate that a decision should be made other than in accordance with the development plan. Having considered all other matters raised I therefore conclude that the appeal is dismissed.