Appeal 3292666

The appeal is allowed and planning permission is granted for proposed single storey rear extension and two front dormer windows at Nuestras, Denham, [postcode] in accordance with the terms of the application, [name]/21/4344/FA, dated 9 November 2021, subject to the following conditions:

The development hereby permitted shall begin not later than 3 years from the date of this decision.

The development hereby permitted shall be carried out in accordance with the following approved plans: 2021/NUES/1B, 2021/NUES/2A, 2021/NUES/3B.

The materials to be used in the construction of the external surfaces of the development hereby permitted shall match those of the existing building.

The main issues are as follow: • 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. • If the proposal is inappropriate development, would the harm by reason of inappropriateness, and any other harm, be clearly outweighed by other considerations so as to amount to the very special circumstances required to justify the proposal.

Local Plan1 Policy GB1 outlines that planning permission will not be granted for development in the Green Belt unless it fulfils certain criteria. One such criterion is ‘f’, which allows ‘Limited extension, alteration or replacement of existing dwellings, in accordance with Policies GB1O and GB11’ of the Local Plan.

Local Plan Policy GB10 relates to extensions to dwellings in the Green Belt and states that such extensions will normally be permitted subject to certain criteria being met. Criterion ‘a’ requires that the extension together with any earlier extensions, would be integral to, and (with the exception of very small dwellings lacking in basic amenities) of a small scale, in relation to the size of the original dwelling. Criterion ‘c’ requires that the dwelling as enlarged would be of a small scale in relation to the size of the residential curtilage.

Neither Local Plan Policy GB1 nor Policy GB10 refer to very special circumstances. They are therefore inconsistent with Framework Paragraph 147. Furthermore, Policy GB10 confines extensions to a small scale, in relation to the size of the original dwelling and residential curtilage. Whilst this does allow for a comparison in size relative to the original dwelling, the Framework does not dictate that such extensions must be ‘small’. For these reasons, neither policy is consistent with the Framework.

Framework Paragraph 149 states that the construction of new buildings in the Green Belt should be regarded as inappropriate development, except in certain circumstances. One such exception is set out under Framework Paragraph 149C, which relates to 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 does not include guidance on what is considered to be ‘disproportionate’. Whether or not extensions and alterations are disproportionate is a matter of planning judgement, having regard to the particulars of a proposed development and the relevant site-specific circumstances.

The Council has provided calculations pertaining to the increase in the floorspace of previous extensions and the proposal in comparison to the original dwelling. Local Plan Paragraph 3.45 suggests that where a proposal results in an increase in floorspace of more than half of the original dwelling, it will not be regarded as small scale. The proposal, when considered in conjunction with previous extensions would exceed this parameter.

I accept that numerical comparisons can be helpful as a means to quantify the threshold of harm, in terms of whether a development constitutes disproportionate additions. However, floorspace alone is a crude measure when used in isolation. For example, it does not recognise the potential to accommodate additional floors in an existing building with only a modest increase in overall volume.

Even taking into account previous extensions to the original dwelling, the proposed development would be of a modest scale and mass. It would clearly have a diminutive appearance when considered in relation to the original 1 South Bucks District Local Plan [name] 1999, [name] 2007 and February 2011 dwelling. Indeed, the maximum height of the main bulk would be significantly lower and the proposal would not extend the rear building line any further than its existing maximum extent. In addition, a large part of the ground floor extension would replace part of the existing ground floor, which mitigates the increase in volume.

In summary, whilst there would be a fairly significant increase in floorspace in comparison to the original building, when taking into account a more wholistic approach to considering ‘size’, the proposed development would not result in disproportionate additions over and above the size of the original building. As such, the proposal would not be inappropriate development.

The impact on openness is implicitly taken into account in the exceptions to inappropriate development unless there is a specific requirement to consider the actual effect on openness. Framework Paragraph 149C does not require an additional consideration of openness. As such, there is no requirement to separately assess the impact of the development on openness.

Incidentally, whilst Local Plan Policies GB1 and GB10 are both out-of-date, the proposal would comply with both given that it would be of a small scale relative to the original dwelling. Whilst the Local Plan text of Policy GB10 does set a parameter for acceptable floorspace increases, the policy text does not include such a parameter and I consider that there is therefore some flexibility in applying other considerations in considering what is ‘small scale’. Even if one were to take a contrary view, the less prescriptive approach to considering ‘size’ in the Framework means that any conflict with Policy GB10 would be of limited weight.

I am imposing the standard householder conditions, as advocated by the government’s Planning Practice Guidance. These are to ensure that the development is implemented in accordance with the approved plans, and that the external materials used should match those of the existing dwelling.

The most important policies in considering this appeal are out-of-date. As such, Framework Paragraph 11d requires that planning permission is granted unless any adverse impacts of doing so would significantly and demonstrably outweigh the benefits, when assessed against the policies in the Framework taken as a whole. I have not identified any adverse impacts and the proposal accords with the Framework’s Green Belt policies. As such, the proposal is supported by Paragraph 11d.

The proposed development complies with the development plan taken as a whole. Whilst the most important policies are out of date, the proposal also complies with the policies in the Framework. The appeal is therefore allowed.