Appeal 3284902

The appeal is dismissed.

The site visit was undertaken by an Appeal Planning Officer whose recommendation is set out below and to which the Inspector has had regard before deciding the appeal.

The main issues are: • whether the proposal would be inappropriate development in the Green Belt for the purposes of the development plan and the National Planning Policy Framework (2021) (the Framework); • the effect of the proposal on the openness of the Green Belt; • if the proposal would be inappropriate development, whether the harm by reason of inappropriateness, and any other harm, is clearly outweighed by other considerations so as to amount to the very special circumstances necessary to justify it.

Paragraph 147 of the Framework states that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Paragraph 149 states that the construction of new buildings should be regarded as inappropriate in the Green Belt, with the exception of, among other things, 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.

Policies GB2 and GB13 of the Chiltern District Local Plan (the Local Plan) and Annex 2 of the [name] and Householder Development Supplementary Planning Document (SPD) are consistent with the information provided in the Framework. Policy GB13 permits extensions which are subordinate to the size and scale of the original dwelling, are not intrusive in the landscape and comply with other policies of the Local Plan. It specifies that where there have been previous extensions, the cumulative effect on the size and scale of the original dwelling will be taken into account.

Both the Local Plan and the Framework define ‘original building’ as the building as it existed on 1 July 1948 or, if constructed after this date, as it was built originally.

The appeal property is a large, two-storey detached building located in the corner of the appeal site, adjacent to [site address] . The property has been previously extended, and although full details of prior developments have not been provided, the Council indicate that this has included single and two-storey additions. The proposal would add a side extension with single and two-storey elements, a porch, and a single-storey extension at the rear that would involve the removal of an existing conservatory.

The extent to which the totality of all additional development, both previous and proposed, would increase the floor area of the original dwelling is a matter of dispute between the appellant and the Council. However, even using the appellant’s lower figure, the existing and proposed extensions in combination would still represent a 79.5% increase in the floor area of the original dwelling.

Neither the Framework, nor development plan policy, define ‘disproportionate’ or stipulate a percentage threshold for development to be considered inappropriate. However, size is a factor not only of floorspace, but will depend on the circumstances of the particular case, and may include built volume, height, width and footprint.

In this case, the proposed single-storey extensions would be modest in scale and overall size, particularly when the removal of the existing conservatory is accounted for. However, the proposed two-storey extension would noticeably increase the width of the dwelling, albeit at a lower ridge height, and would add further bulk to the dwelling. These extensions would therefore increase the footprint, bulk and massing of the dwelling. Although they would only be easily seen from within the site, they would nevertheless result in a visible increase in the size of the dwelling.

In combination with the prior additions to the building, the proposal would significantly increase the size of the property, and would not appear subordinate in size and scale to the original dwelling. Consequently, I find that while the proposals would be relatively modest in relation to the existing dwelling, the cumulative effect with previous extensions would result in disproportionate additions over and above the size of the original building.

Accordingly, the proposal would be inappropriate development in the Green Belt and therefore would result in harm to the Green Belt. Paragraph 148 of the Framework instructs that substantial weight should be given to any harm to the Green Belt, and that ‘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.

Neither the Council nor the appellant have fully addressed the proposal’s effect upon the openness of the Green Belt. Openness is one of the essential characteristics of Green Belts however, therefore it is necessary for me to consider this in order to assess the effect of the proposed development on the Green Belt.

The appeal site is relatively large and, internally, relatively open. It is however enclosed by tall trees and considerable vegetation. Beyond this, the area in the vicinity of the site is generally free of buildings. The proposed porch would be limited in size, and part of the rear extension would occupy the same footprint as the existing conservatory. However, it would also extend beyond this slightly. The two-storey side extension would be positioned on an existing paved area, be set back from the front elevation, and have a lower ridge height than the main roof. It would also be generally obscured from public views. However, the side extensions would occupy much of the space between the northern elevation of the existing property and the northern boundary.

Therefore, the proposal would result in some loss of openness in both visual and spatial terms. Nonetheless, given the degree of screening and the siting of the proposed extensions, the overall impact on the openness of the Green Belt would be very limited, albeit a matter to which I must afford substantial harm.

The proposal would represent an improvement to the layout of the property and the standard of accommodation, and meet the appellant’s desires for contemporary family life. However, the improvements would be a private benefit, and given that it has not been demonstrated that the property could not provide suitable, liveable accommodation in its existing form, this carries limited weight.

The design of the proposed extensions would be appropriate to the existing dwelling and the surrounding area, therefore I find no conflict with Policy CS20 of the [name] for Chiltern District (November 2011) which requires good design. However, good design is to be expected for all development. The proposal would result in a small improvement in the appearance of the dwelling through a more coherent appearance at the rear, however this would be of very little benefit given the lack of public views of this area and carries very limited weight.

The appellant has made general reference to other extensions approved by the Council that have resulted in greater percentage increases in floor area. I have no details of these extensions or how they came to be built, therefore I cannot conclude that they are comparable to the appeal proposal in relation to the original host building, nor am I aware whether very special circumstances were found to exist. Accordingly, these carry very little weight.

The proposal would be inappropriate development in the Green Belt and would be detrimental to openness, matters which I afford substantial weight. It would therefore conflict with Policies GB2 and GB13 of the Local Plan, the Framework, and the aims of the SPD. The other considerations do not clearly outweigh these harms, and the very special circumstances necessary to justify the development do not therefore exist.

In the interests of clarity, having regard to the appellant’s comments on the matter of openness, even if I had not found any harm in relation to openness, the harm as a result of inappropriateness would not be clearly outweighed by the other considerations in this case. Therefore, I would have reached the same conclusion overall.

Based on the above, and having regard to all matters raised, I recommend that the appeal should be dismissed.

I have considered all the submitted evidence and the Appeal Planning Officer’s report and on that basis the appeal is dismissed.