Appeal 3308486

The appeal is dismissed.

The main issues are: (i) whether or not 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; (ii) the effect of the proposal on the openness of the Green Belt; and (iii) 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.

[site address] is a substantial two-storey detached dwelling situated in the Green Belt. The dwelling is set within a generous plot and is accessed by a private drive serving mainly two-storey dwellings of varied design.

Paragraph 149 of the Framework states that the construction of new buildings should be regarded as inappropriate in the Green Belt other than in a number of exceptions. One exception at Paragraph 149 c) 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. Policy 49 (The Green Belt) of the London Borough of Bromley Local Plan (2019) (LP) confirms the same.

What constitutes a disproportionate addition is not defined within the Framework. However, Policy 51 (Dwellings in the Green Belt or on [name]) of the LP sets out that extensions to dwellings in the Green Belt will only be permitted if all of criteria (a) – (c) of the policy are met. Without any alternative definition, the specific requirements of the development plan are particularly pertinent to my considerations as to what constitutes a disproportionate addition.

Criteria (a) requires that the net increase in the floor area over that of the original dwellinghouse is no more than 10%, as ascertained by external measurement. The policy does not set out any exceptions to this threshold. The evidence before me indicates that the original dwelling was previously extended and that this increased its floor area by 7%. The Council has calculated that the proposal, together with the previous extension, would equate to a 14.5% increase over the original floor area. Consequently, the proposal would clearly conflict with criteria (a) and the appellant has not disputed the Council’s calculations.

I have considered matters of openness and design later in this decision, aspects of which are relevant to the considerations under criteria (b) and (c) of Policy 51. In any case, as all criteria under Policy 51 are required to be met and the proposal conflicts with criteria (a), the proposal would be a disproportionate addition to the dwelling having regard to the specific limits for extensions to dwellings in the Green Belt set out in the LP.

I conclude, the proposal would be inappropriate development in the Green Belt having regard to the requirements of Policies 49 and 51 of the LP and the Framework.

Paragraph 137 of the Framework sets out the essential characteristics of Green Belts, which are their openness and permanence. It has been held in the [address] that openness is epitomised by the lack of buildings or development.

There would be a spatial impact by virtue of the increased footprint and volume resulting from the extension. The extension would set back from the front elevation of the dwelling and between its flank wall and detached garage. Consequently, the extension would only be partially visible to passers-by on [site address] to the limited extent that it would protrude above the height of the front boundary wall.

Taken together, the spatial and visual impacts of the extension would have a modest effect on the openness of the Green Belt. In that regard, there would also be some tension with the requirement at criteria (b) of Policy 51 of the LP which requires that development does not harm open character.

Overall, the extension would not preserve the openness of the Green Belt, thereby conflicting with the aims of including land within the Green Belt when assessed against the Framework.

I accept that the proposal would be subordinate to the host dwelling and is not a stand-alone structure. The Council’s report also identified that the general design and materials would appear in keeping with the general character of the dwelling and I do not disagree. For these reasons, I have not identified specific conflict with Policies 6 ([name]), 37 (Design) or criteria (c) of Policy 51 of the LP. Even so, acceptable design alone is not a justification for a disproportionate extension in the Green Belt.

The appellant suggests that the proposal offers an opportunity to enhance the soft landscape elements of the locality. However, no specific proposals are before me. Therefore, I am not persuaded that any such proposals would result in visual or biodiversity benefits of a significant magnitude.

The development constitutes inappropriate development in the Green Belt to which I attach substantial weight. The Framework states that inappropriate development is by definition harmful to the Green Belt and should only be approved in very special circumstances.

As part of the assessment, I have also found that the development would result in a modest effect on the openness of 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, is clearly outweighed by other considerations. This is a high hurdle for a development proposal to overcome.

The other considerations put forward in favour of the proposal only carry very limited weight.

In conclusion and on balance, the substantial weight to be given to Green Belt harm, in addition to the other harm identified is not clearly outweighed by other considerations and therefore the very special circumstances needed to justify the proposed development do not exist.

For the reasons given the overall conclusion is therefore that the appeal should be dismissed.