Appeal 3326148

The appeal is dismissed.

The main issues are: • Whether or not the proposed roof dormer would preserve or enhance the character or appearance of the De Freville Conservation Area. • The effect of the proposed single storey rear extension on the living conditions of the occupiers of [address], with particular regard to outlook.

The appeal property lies within the De Freville Conservation Area (the CA). In having regard to the De Freville Conservation Area Appraisal 2020 (the CAA), I find that the significance of the CA is derived from the relationship between the formalised grid-like street pattern, and the long rows of traditional period style dwellings, which front onto the streets. The dwellings in the CA tend to display a strong sense of uniformity in terms of style and materials, which gives the CA a cohesiveness of appearance that is reflective of the expansion of this part of the city in the nineteenth century.

The appeal property is a 2 storey mid-terraced period style dwelling set within a long row of similar style dwellings on the east side of [address]. Several properties in the row have been altered and extended, including with the addition of a number of box-like roof dormers on rear roof slopes, including some on the roofs of rear outriggers. However, those on the roofs of rear outriggers are not so numerous as to be a characteristic feature of the CA.

The scale, form and pattern of the outriggers on the rear of the host property and terrace are consistent in scale and appearance, and they contribute to the terrace’s architectural composition and hierarchy of elements. As the appeal property displays characteristics common to the period style dwellings in the area, it makes a positive contribution to the character and appearance of the CA, and thus its significance.

In determining this appeal, I must have regard to my statutory duty under s72(1) of the Planning (Listed Building and Conservation Areas) Act 1990 (the Act) to pay special attention to the desirability of preserving or enhancing the character or appearance of conservation areas.

The Council’s Roof Extensions Design Guide (the [name]), contained in [name] of the Cambridge Local Plan, October 2018 (the CLP), and referenced in CLP Policy 58, states that roof extensions must be appropriate in size, scale and proportion to the existing house and adjoining properties, and must not be so large as to dominate the existing roof or to overwhelm their immediate setting.

The proposed L-shaped dormer would be set on the appeal dwelling’s rear facing roof slope and the side facing roof slope of its rear outrigger. Although it would not extend across the full depth of the outrigger and its chimney stack would be retained, the proposed dormer would nonetheless be a large addition to the outrigger’s roof and would cover a significant proportion of its side facing roof slope. It would project noticeably above the outrigger’s roof ridgeline, and its box-like form and elevated mass would disrupt the shape of the appeal property’s outrigger. As such, it would unbalance the distinctive pattern of rear projecting outriggers to the terrace, and the use of matching brick for parts of the external surfaces of the dormer would emphasise its presence in the roofscape.

In views from nearby gardens, the part of the proposed dormer on the roof slope of the rear outrigger would be a visually dominant and discordant addition to the roof of the host property. It would have the effect of disrupting the host property’s architectural composition and hierarchy of elements, including those of the wider terrace. Consequently, it would erode the terrace’s strong sense of uniformity of appearance and its positive contribution to the CA. The use of high-quality materials would not overcome this harm.

I acknowledge that the proposed dormer would be at the rear of the property and therefore screened in views from a public vantage point. I have also had regard to the advice in the [name] that a more flexible approach should be taken to roof extensions which are not visible from the public realm. However, I must exercise my statutory duty under the Act, to pay special attention to the desirability of preserving or enhancing the character or appearance of conservation areas. Furthermore, the policies referred to above are not limited to developments visible only from a public vantage point. As such, the inability to view the proposed development from a public vantage point does not alter my conclusions on this main issue.

Even if the massing of the proposed dormer would be only marginally larger than the Council’s proposed amendments, as suggested by the appellant, I have limited evidence that an alternative development with comparable effects could be implemented were this appeal to fail.

Several examples of box-like dormers granted planning permission in the CA have been drawn to my attention, including submissions of the planning drawings and accompanying Council Officer Reports. Compared to the case before me, the examples of roof dormers on properties on [address] are set back from the roof eaves of their outriggers, resulting in a materially different relationship to the outrigger. Furthermore, those examples (with the exception of the scheme at Number 12), predate the CLP and were therefore permitted under a different policy context, and under earlier versions of the [name]. I have no evidential basis to assume that the guidance on roof extensions in the [name] before me in this appeal, is the same as those earlier versions.

The details of the development at Number [address] do not appear to show a dormer to the outrigger and is therefore materially different to the appeal scheme.

The dormer at Number [address] covers the rear outrigger’s side facing roof slope and its side wall appears to be built directly above the external side wall of the outrigger. Although this dormer is visible with the appeal property, it does not appear to project noticeably above the roof ridge of the outrigger. Furthermore, compared to the buildings on the east side of [address], including the terrace of which the appeal property forms part of, the dormer at Number 55 is seen amongst a roofscape displaying a greater variety to the styles of houses. As such, it is materially different in context to the proposal before me in this appeal.

The recently approved dormer above the outrigger at Number [address] is visible from the public realm in the CA. However, the submitted drawings show that it is also set back from the host property’s roof eaves. Even if the dormer above the outrigger at Number [address], was of a greater massing than the proposed dormer in the case before me, I note in the Planning Officer’s Report that it was described as “sandwiched” between two similarly designed roof dormers. As such, the dormer at Number 21 has a materially different relationship with its surroundings than the case before me in this appeal. Furthermore, none of the dormers on [address], drawn to my attention, would have a visual relationship with the rear of the appeal property and terrace.

Some broad similarities can be drawn between the roof dormer proposed in this appeal and the examples of existing dormers submitted in evidence. However, for the reasons given, those examples are materially different to the proposal before me. As such, they do not alter my conclusions on this main issue, which I have determined on its individual merits based on the evidence before me, the prevailing policy context, and my observations at the site visit. In any case, I am not bound by previous decisions of the Council.

I note that the CAA identifies that numerous attic conversions have taken place in the CAA since 2009. However, this does not mean that all attic conversions that leave the street frontage unchanged would preserve or enhance the character or appearance of the CA. As such, the CAA does not alter my conclusion on this main issue. The CAA specifically identifies [address], in the context of ‘enhancements and future developments’, as a street where rear extensions, although not often readily visible to the street scene, do not always make a positive effort to use sympathetic roof lines or scale, and can be intrusive.

The Council did not find the proposed rooflights in the front roof slope to be harmful to the CA, and I see no reason to disagree. However, an absence of harm in this respect would not weigh positively in favour of the proposal.

For these reasons, I find that the appeal proposal would erode the positive contribution made by the appeal property to the character and appearance of the CA. As such, I conclude on this issue that it would fail to preserve or enhance the character or appearance of the CA, contrary to [name] 55, 58 and 61. [name] seek to ensure that development, including dormers, which creates altered or new roof profiles, is sympathetic to the existing building and surrounding area, and does not adversely affect the character or appearance of heritage assets.

In terms of the National Planning Policy Framework1 (the Framework), the harm that would be caused by the proposal to the significance of the CA as a designated heritage asset would be less than substantial. Nevertheless, this is a matter of considerable weight and importance, and Paragraph 205 of the Framework requires me to weigh this harm against the public benefits of the proposal.

The appeal building would be modernised through measures aimed at complying with [name] 28, 29, 30, 31 and 36, including meeting thermal insulation requirements, fitting an air source heat pump along with mechanisms to regulate air quality, humidity, and heat loss. Fossil fuel supply to the property would be removed. However, I have limited evidence before me to quantify the reduction in carbon dioxide emissions that the appeal proposal would achieve. In any case, I am not persuaded that the appeal proposal would be the only means of improving the energy efficiency of the building and reducing carbon dioxide emissions. As such, I attach limited weight to these public benefits.

The environmental benefits attributed to the proposed green roof in terms of biodiversity gain, thermal regulation and managing rainwater, would be likely to be modest given the scale of the roof. As such, I attach limited weight to these public benefits.

Even if the planned renovations to rectify some unsympathetic, non-original features, were to improve the appearance of the building and enhance the CA, and utilise reclaimed materials, I have no substantive evidence that such renovations are contingent on permission being granted for the appeal proposal.

Consequently, I give these matters limited weight insufficient to outweigh the harm I have identified. Accordingly, the public benefits associated with the proposal would not outweigh the considerable importance and weight that even less than substantial harm to the significance of the designated heritage asset carries. As such, there is conflict with the conserving and enhancing the historic environment objectives of the Framework.

CLP Policy 56 appears to relate to the structuring elements of creating successful places, including spaces between buildings, built frontages, street 1 Version published 19 December 2023 furniture and clearly defined public spaces. Compared to the [name] referred to above, I do not find CLP Policy 56 determinative to my considerations on this main issue.

The relatively long and solid side wall of the proposed extension would extend along the common boundary with Number 38 (No 38), for a considerable distance and would project above the timber fence on the common boundary. Although its design features a chamfered style roof slope between the side wall and the flat roof, the height and massing of the side wall of the proposed extension would nonetheless be visible at a close distance from the clear glazed ground floor window in the side facing wall of the outrigger of No 38, and the partially clear glazed ground floor door in the rear wall of No 38. The evidence suggests that the window and doors serve a breakfast room and dining room respectively.

Set at such a close distance to the side wall of No 38, the side wall of the proposed extension would have a dominant and overbearing effect on the occupiers’ outlook from the breakfast room window in No 38. Furthermore, the height, length and closeness of the proposed extension to No 38, would noticeably narrow the field of view for occupiers looking out of the dining room doors. The resultant view out of the dining room would be largely through the relatively narrow space that would remain between the two buildings. As such, the proposed extension would have a dominant and overbearing effect on the occupiers’ outlook from the dining room in No 38.

The proposed ground floor extension would be visible from the narrow part of the garden of No 38, that is situated between the side wall of its rear outrigger and the common boundary. However, the narrowness of this space restricts its usability for relaxation and recreation by the occupiers. In this context, the proposal would not unacceptably harm the occupiers’ enjoyment of their outdoor amenity space. However, this would not outweigh the proposal’s harmful effect on the occupiers’ living conditions that I have identified above.

In considering the appeal proposal on its individual merits based on my experiences at the site visit, it is not necessary for me to draw comparisons with a pitched roofed design of an extension that is not before me in the evidence. The rooflights in the proposed flat roof may help prevent views into the proposed extension and limit the visible glow of light during hours of darkness. The proposed flat roof would allow for a green roof and make it easier for rooflights to be cleaned. The roof slope of the proposed rear extension would allow traditional slate to be used, reflecting that used in the existing building. However, these factors hold limited weight in favour of the proposal and do not outweigh the harm I have identified.

I have taken account of the planning permissions for several single storey rear extensions to terraced dwellinghouses in the locality. The side walls of most of those examples would be set on the common boundary and facing an adjacent dwelling, as the appeal proposal would be. However, in most of those examples, the submitted drawings do not show full details of the internal layouts of the adjacent properties or the rooms served by any windows facing those approved extensions. As such, I cannot be certain that the effects of those examples on the living conditions of the occupiers of the properties that are adjacent to them, are comparable to the case in the appeal before me. In determining this appeal, I am not bound by the decisions of the Council and the approval of apparently similar proposals would not justify me granting permission for a development that would cause harm. I have determined the appeal proposal on its individual merits and the examples cited do not alter my conclusion on this main issue.

For these reasons, I conclude on this issue that the proposed development would harm the living conditions of the occupiers of [address], with particular regard to outlook. As such, it would be contrary to CLP Policy 58, insofar as it seeks to ensure that development does not visually dominate neighbouring properties.

[name] 55 and 57 are cited in the second refusal reason. However, as CLP Policy 55 relates to the issue of design and appearance of development, and CLP Policy 57 relates to new buildings, which this proposal does not, I do not find either policy to be determinative to my considerations on this main issue.

I have already found that limited weight attaches to the public benefits of the appeal proposal. As a private benefit, I give limited weight in the proposal’s favour to the appellant’s aspirations to improve and enlarge the interior space within the building to make it more suitable for family living and home working. There is limited evidence that the existing building is harming the health of the occupiers or the fabric of the building.

The Council did not refuse permission on noise grounds or a loss of privacy to nearby occupiers. Even if I was to agree with the Council on these points, an absence of harm does not weigh positively in favour of the proposal.

I see no basis why my decision on this appeal, which is based on its individual merits and context, would stifle innovation in the design of roof extensions.

For the reasons given above and having considered all matters raised, I conclude that the proposal conflicts with the development plan as a whole and the conflict is not outweighed by any material considerations. The appeal should be dismissed.