Appeal 3325114

The appeal is dismissed.

An update to the National Planning Policy Framework (the Framework) was published on 19 December 2023. Other than changes to paragraph numbering, there are no material changes relevant to the substance of the appeal.

The main issues are: • whether the proposal would comprise inappropriate development in the Green Belt having regard to the Framework and the development plan; • the effect of the proposal on openness and the five purposes of the Green Belt, as set out in the Framework; and • whether any harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations that would amount to the very special circumstances required to justify the proposal.

The appeal site is a detached dwelling and the proposed development comprises various extensions and alterations at ground and basement levels. The appeal site lies in the Green Belt.

Paragraph 154 of the Framework establishes that the construction of new buildings should be regarded as inappropriate in the Green Belt, unless they fall within one of several exception criteria listed, among which is 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.

The Framework and the development plan provide no specific definition or threshold as to what would amount to disproportionate additions. However, the Supplementary Planning Document: Residential Design Guidance – October 2016 (the SPD) sets out a guiding principle that extensions to dwellings within Barnet’s Green Belt should not increase the original volume by more than 25%.

The appellant’s submission sets out that the cumulative increase to the volume of the original dwelling, comprising the appeal proposal and previous additions, would amount to 76%.

In the absence of any alternative definition, the approach set out in the SPD is a material consideration. The proposal would result in the cumulative increased volume being more than 3 times the SPD figure. Even interpreting the 25% figure flexibly, in my view the proposal, taken together with previous additions, would clearly result in disproportionate additions over and above the size of the original building.

I am provided with a previous appeal decision elsewhere in the borough at [address], which granted planning permission for what the appellant describes as an 82% increase above the existing floor space. [name] am not provided with full details of the proposal, the description relates to a basement development, and I accept there may be similarities with the current proposal.

In concluding that the proposal would not amount to a disproportionate addition, and therefore not inappropriate development in the Green Belt, the previous Inspector considered several factors, including that it would not increase the footprint of the building and would not have a material effect on the external appearance of the building or on its visual bulk in the Green Belt.

[name] note the considerations above, I have determined the current appeal on its own merits. Furthermore, in determining whether or not the proposal would be inappropriate, I am required only to consider whether the sum total of existing and proposed extensions, when taken together, would amount to disproportionate additions over and above the size of the original building. The appeal at [address] would therefore not alter my previous findings in relation to this issue.

For the reasons given above, the proposal, when considered together with previous additions, would comprise a disproportionate addition over and above the size of the original building and would therefore be inappropriate development in the Green Belt. It would therefore conflict with [name], CS1 and CS7 of Barnet’s Local Plan ([name]) Development Plan Document – September 2012 (the CS), Policies DM01 and DM15 of Barnet’s Local Plan (Development Management Policies) Development Plan Document – September 2012 (the DMP), and Policy G2 of the London Plan – March 2021 (the LP). Together these policies seek, among other objectives, to reflect the provisions of the Framework and to resist development in the Green Belt other than in exceptional circumstances. The proposal would also conflict with the provisions of the Framework, as set out above.

Because the proposal would comprise inappropriate development in the Green Belt, I must consider its effect on openness.

The northern boundary of the site provides views to and from adjoining fields. More robust treatments are present to the other site boundaries, which would largely screen views of the proposal from neighbouring dwellings and public spaces outside of the site.

With much of the structure being submerged, the visual effects of the proposal would relate to the ground floor extension and the groundworks required to facilitate the basement. There would be limited visibility of these elements of the development from outside of the site, and they would not be of significant scale when viewed internally. Nevertheless, they would increase the massing of the building and result in a small reduction to the visual openness of the Green Belt.

The Planning Practice Guidance (the PPG) establishes that openness has both a visual and spatial aspect. I have already concluded that the volume of the original building would increase disproportionately. The proposal would also increase the area of the site occupied by built development. Although the external indicators of this would be largely limited to the modest rear extension, groundworks and the glazed rooflights of the basement, the proposal would nevertheless result in a small reduction to the spatial openness of the Green Belt.

Although the proposal would reduce the openness of the Green Belt, the effects would not be of such magnitude that the proposal would conflict with any of the five purposes of including land in the Green Belt, as set out in paragraph 143 of the Framework.

Paragraph 142 of the Framework states that the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open; the essential characteristics of Green Belts are their openness and their permanence. Although the proposal would not conflict with any of the five purposes of including land in the Green Belt, there would be a small impact on the openness of the Green Belt in both visual and spatial terms, which would conflict with [name], CS1 and CS7 of the CS, Policies DM01 and DM15 of the DMP, Policy G2 of the LP, and the Framework, the aims of which have been previously set out.

The appellant submits a potential fallback position that the development subject to the appeal would have significantly less impact on the openness of the Green Belt than works to the property that could take place under permitted development. It is also suggested that a condition could be imposed, in the event of the appeal being allowed, to remove certain permitted development rights to limit the scope for future development.

The site benefits from two certificates for lawful proposed development for detached single storey buildings that have not been implemented. However, other than a description of the proposals, I am provided with limited details of the schemes subject to the lawful development certificates, or any other potential development that might take place under permitted development. As such, I am presented with insufficient evidence to compare the effects of these schemes to the appeal proposals. Accordingly, these considerations carry only limited weight.

The appellant also submits that the appeal proposal would deliver additional benefits through reducing the amount of hardstanding on the site. However, the reduction in hardstanding would not amount to a significant area and I can only attach a small amount of weight to this consideration.

Paragraph 152 of the Framework establishes that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Paragraph 153 goes on to explain that substantial weight should be given to any harm to the Green Belt. ‘Very special circumstances’ will not exist unless the potential harm to the Green Belt by reason of inappropriateness, and any other harm resulting from the proposal, is clearly outweighed by other considerations.

I have identified that harm would occur to the Green Belt through inappropriateness and loss of openness, and I must give substantial weight to this harm. The other considerations noted above carry limited weight in favour of the proposal and do not clearly outweigh the substantial weight I must give to the harm to the Green Belt. Consequently, the very special circumstances necessary to justify the development do not exist.

For the reasons set out above, the proposal would conflict with the development plan as a whole and there are no material considerations, including the Framework, to indicate 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 should be dismissed.