Appeal 3306416

The appeal is dismissed.

The main issues are: • whether the proposal would be inappropriate development in the Green Belt having regard to the National Planning Policy Framework (the Framework) and any relevant development plan policies, • the effect of the proposal on the openness of the Green Belt, and • whether any harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations, so as to amount to the very special circumstances required to justify the proposal.

The appeal site is a semi-detached house situated in the Green Belt. Paragraph 149 of the Framework states that the construction of new buildings should be regarded as inappropriate in the Green Belt. It goes on to set out some exceptions, which include ‘the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building’ (paragraph 149c). Framework Annex 2 defines the ‘original’ building as being the building as it existed on 1 July 1948.

Core Strategy1 Policy CS13 similarly sets out a presumption against inappropriate development within the Green Belt. Policy SADM26 of the Site 1 Hertsmere Local Plan, [name] adopted January 2013 Allocations and Development Management Policies Plan2 lists several criteria for assessing development in the Green Belt. These include amongst other things that an extension to an existing building must not individually or cumulatively be disproportionate to the original building.

Policy SADM26 goes on to state that when judging scale, the Council will take into account proposed changes in floorspace, volume, site coverage, height and orientation. No mathematical threshold is specified. Likewise, the Framework does not provide any specific threshold beyond which an extension is deemed to be disproportionate.

In comparison with the existing dwelling, the proposed extension would be of modest scale and subservient, single storey design. However, both the Framework and the development plan require that the cumulative effect of all additions is considered, in comparison with the original building and not the building as it currently stands.

In this case, there have been two sizable previous additions, comprising a two storey extension to the side of the dwelling and a part two storey, part single storey extension to the rear. The Council states that these have resulted in a combined 88.7% increase over the original floorspace and that the proposed extension would result in an overall increase exceeding 102% of the original floorspace. These figures have not been disputed.

As such, the extended dwelling would be just over double the size of the original dwelling. When considered in combination, the extensions would wrap around the whole of the rear and side elevations, significantly increasing the bulk of the original building. Furthermore, the proposed extension would, in itself, increase the external volume of the dwelling to a modest but material degree. There would be an increase in site coverage, since the footprint of the building would be enlarged.

Taking all these factors into consideration, when considered in combination with the previous extensions, the proposal would result in disproportionate additions over and above the size of the original building. I therefore conclude that the proposal would be inappropriate development in the Green Belt. Such development is, by definition, harmful. As such, the proposal would conflict with Policies CS13 and SADM26, and with relevant paragraphs in the Framework, as summarised above.

Openness is an essential characteristic of the Green Belt that has spatial as well as visual aspects. It relates to the presence or otherwise of built development, as distinct from any consequent effect on the character and appearance of the surrounding area.

The proposed extension would increase the footprint and external volume of built development on the site. Therefore, there would be some harm to openness in spatial terms, as a result of the increased building mass. However, the site is within a row of existing dwellings and the extension would be well contained within the existing garden area. It would not be a stand-alone structure and would not intrude into the gap between existing buildings. 2 Hertsmere Local Plan, Site Allocations and Development Management Policies Plan, adopted November 2016

Views into the site from the road are screened by a series of hedges and close boarded fencing on rising ground alongside the dwelling. The extension would not be visible, provided this boundary screening is retained. Land to the rear is more open, since the site adjoins an open field without intervening boundary screening. Nevertheless, in any available views across the field, the extension would be seen against the backdrop of the existing two storey dwelling. As such, the effect on openness in visual terms would be very limited. To that extent, the proposal responds positively to design criteria in Policy SADM26 which include that development should be unobtrusively located and take advantage of landscape features to minimise visual impact.

For the above reasons, while there would be some loss of openness by virtue of the increased building mass, I conclude that such harm would be at a modest and very localised level.

The proposal would provide increased and more flexible space to support home working and the evolving needs of an extended family. A lack of suitably affordable housing for adult children is highlighted as a contributory factor. There is some support in the neighbourhood plan3 for flexible accommodation which supports home working and evolving family needs.

[name] have due regard to these benefits, I am mindful that similar issues arise throughout areas designated as Green Belt. Therefore similar arguments could be repeated elsewhere, with a harmful cumulative effect on the Green Belt’s essential characteristics. On that basis, I have given the provision of additional, more flexible accommodation modest weight.

By virtue of its modest proportions, rearward siting and extensive glazing, the extension would be visually subordinate to the existing dwelling. However, both the Framework and the development plan require consideration of the cumulative effect of extensions compared to the original building. Any similarity with the scale of other nearby dwellings is not a relevant consideration. In consequence, even small and visually subordinate extensions can be precluded if the host building has already been extended to a significant degree.

The Council has not alleged any harm to the character and appearance of the dwelling or the Conservation Area within which it is located. Having considered the development and visited the site, I have no reason to reach a different view. However, this is a neutral factor which weighs neither for nor against the proposal. Similarly, the use of matching materials, retention of existing landscape features and absence of any change of use or intensification are neutral considerations.

The proposal would not involve the unrestricted sprawl of a large built-up area, would not encroach further into the surrounding countryside and would not result in the merging of settlements. No specific conflict is alleged with aspects of the Framework relating to design, development in the countryside more generally or wider aspects of sustainable development. However, this does not negate the conflict with Framework paragraph 149(c) and the consequent conflict with the Framework when considered as a whole. 3 Shenley Neighbourhood Plan, ‘The Shenley Plan 2019 to 2036’, made May 2021

I have concluded that the proposal would be inappropriate development in the Green Belt as defined in the Framework and relevant development plan policies. There would be harm to the openness of the Green Belt, albeit at a modest and very localised level.

The Framework requires that any harm to the Green Belt be given substantial weight. While a number of factors have been highlighted in favour of the proposed development, I have given those factors modest weight for the reasons set out above. Therefore, whether considered individually or cumulatively, the harm to the Green Belt is not clearly outweighed by any other considerations. In consequence, the very special circumstances necessary to justify the proposal do not exist.

I have not been provided with any evidence indicating that the development plan policies which are most important for determining the application are out of date. Even if such evidence had been provided, given the conclusions I have reached above there is a clear reason for refusing the development proposed based on the application of policies in the Framework that protect areas of particular importance, namely the Green Belt. Therefore, the proposal does not benefit from the presumption in favour of sustainable development, for reasons set out in paragraph 11 d) i. of the Framework.

For the reasons set out above, the Green Belt harm is not clearly outweighed by the other considerations and the very special circumstances necessary to justify the proposal do not exist. Therefore, having had regard to the development plan as a whole, along with all other relevant material considerations, I conclude that the appeal should be dismissed.