Appeal 3351173

The appeal is dismissed.

The description of development on the application form is not the same as used by the Council on its decision notice. I have referred to the description as set out on the application form but have taken into account all the extensions and alterations as proposed and as shown on the plans as determined by the Council.

The appellant has set out the application process with the Council, but my decision is required to be based on the planning merits of the case before me.

The main issue in this appeal is whether the proposed extension would be inappropriate development in the Green Belt and, if so, whether other considerations clearly outweigh the harm to the Green Belt, and any other harm, so as to amount to very special circumstances.

The appeal property is a detached residential dwelling on the east side of [address] within a ribbon of development along this side of the road, and within the Green Belt. The land slopes steeply down from front to rear.

As existing the property is single storey with rooms in the roof, including a dormer and roof light at the front and three dormers at the rear, all set within a hipped roof. The extension would propose to extend the roof to change from a hipped roof to a half-hipped roof with the addition of a dormer window at the front, rear bay window at the ground floor and creation of a lower ground floor with lightwell.

Paragraph 154 of the National Planning Policy Framework (Framework) sets out that the construction of new buildings in the Green Belt is inappropriate except for a limited number of exceptions including the extension or alteration of a building providing that it does not result in disproportionate additions over and above the size of the original building. The term disproportionate is not further defined.

The Council has referred to Policies CP8, Policy DM42 and Policy DM43 of the Wycombe District Local Plan (Local Plan). Policy CP8 seeks to protect the Green Belt, including from inappropriate development and the Council’s approach to managing development in the Green Belt is further set out under Policy DM42. Policy DM43 is a criteria based policy which seeks to set out more details of when a proposed replacement or extension of a dwelling (including outbuildings) would be regarded as inappropriate or not inappropriate development in the Green Belt. Although the policies predate the Framework, I consider that they accord with the principles of the Framework and full weight can be accorded to them.

Point 1 of Policy DM43 deals with the extension or replacement of dwellings. Criteria d, e and f of Policy DM43 Point 1 relate to an assessment of the increase in size by reference to the volume of the original building. The Council has calculated that the volume of the original dwelling was 284.43 m3 whereby criterion e) would allow a volume increase of 50% over the volume of the original building. The supporting text defines the original building as it existed on 1 July 1948 or if constructed after that date, the first building constructed. Taking account of existing extensions together with the proposed, the volume would be 655.33 m3 resulting in approximately a 130% increase over the original volume. This would not accord with criterion e).

The Appellant has contested the figures used by the Council following a detailed survey of the property undertaken. This assessment indicates that the ‘original’ building should have been 349 m3 but this would still bring it into criterion e) where the range of the volume of the original building is given as between 240 and 720 m3. The appellant contends that the volume of the development as proposed taking into account previous works would be 688.33 m3. Using these figures, and although less than the Council’s figures, this would still result in a volume increase significantly above the policy limit of 50% volume increase above the original building.

The same policy also has an alternative approach under criterion c) which states that where the dwelling is within a ribbon of development that presents a substantially built up frontage, the resultant dwelling would not exceed the average volume of its two directly adjacent neighbours. On the basis of both the Council’s and the appellant’s figures for the appeal property and the Council’s figures for the two immediately adjoining properties, the proposal would also not accord with this criterion.

Although the proposal would not significantly extend the footprint of the building, the change to the roof form would result in a noticeably bulkier and more substantial building. Views of the enlarged building would be evident from along [address]. The proposal would therefore result in some impact on the openness of the Green Belt, in spatial and visual terms, through the increased bulk and massing and overall prominence of the building.

The appellant has contended that the development might also be considered to fall under the exception to inappropriate development at paragraph 154 g) of the Framework, relating to limited infilling or the partial or complete redevelopment of previously developed land. This exception has two caveats and of relevance here would be that the resulting development would not have a greater impact on the openness of the Green Belt compared to the existing development.

There are a number of considerations to take into account in considering this exception. The first is whether the site falls to be considered as previously developed land. Land in built up areas such as residential gardens is excluded from the definition of previously developed land in Annexe 2: Glossary to the Framework but the Framework does not define the term ‘built up areas’. I have taken into account relevant case law but do not agree with the appellant’s view that garden space and land associated with a residential property in the Green Belt is always considered to be previously developed land; this is not clarified in the Glossary to the Framework.

Although there is open land on the other side of [address], the appeal site is within a ribbon of built development with further built development to the rear. I therefore consider that for the purposes of this appeal the site should be considered as within a built up area. The site may contain a permanent structure, but it is also a residential garden and is not therefore previously developed land. Furthermore, the proposal before me would not fall to be considered as infilling or the complete redevelopment of the site, and I am not persuaded that the proposals would properly fall to be considered as ‘partial redevelopment’. In any event, I have found that there would be a greater impact on openness so even if I were wrong on either or both of the above, this exception would not therefore apply.

Taking all these factors into account and having regard to the relevant policies of the Local Plan and the Framework, it is my view that the proposed extension would be a disproportionate addition to the original house and would therefore be inappropriate development. The extension would also harm the openness of the Green Belt, in both spatial and visual terms, through the increased bulk and massing of the building.

The proposal would result in a noticeably bulkier and therefore more dominant building compared with the existing. However, given the variety of building forms in the immediate vicinity I consider that it would be assimilated into and not materially harm the character and appearance of the local area and there would be no harm to the amenities of surrounding neighbours. However, a high standard of design and a design solution which respects the amenities of existing and future occupants is to be expected in accordance with national and local plan policies. The absence of any other harm does not provide weight in favour of the proposal but is neutral in my overall assessment.

The appeal property benefits from two certificates of lawful development, one for an extension and one for an outbuilding. The single storey side extension was granted in January 2024 under the Ref: 23/08011/CLP and the single storey detached outbuilding for use as a games room/home office/ shower on the same date under the Ref: 23/08013/CLP. The information provided by the appellant indicates that there is a greater than theoretical possibility of these schemes being implemented were planning permission not to be granted for the proposed scheme before me. I have no reason to take a different view and having regard to relevant caselaw, they therefore attract significant weight as a fallback position.

I also have no information before me to dispute the figures set out by the appellant that the combined volume of these two proposals would add just over 168 m3 to the site and would therefore add more volume to the site than the proposal before me. I have also taken into account the Council’s contention that the relevant policy (DM43 of the Local Plan) separates out the consideration of extensions and outbuildings.

Although it has not been confirmed in the information before me, it appears that it would probably not be possible to build the side extension as permitted as well as the proposal before me because of the change to the roof form and roof slopes. The volume of this permitted scheme would be 54 m3. There would be benefits from this scheme not being built out in terms of not encroaching close to the side boundary. However, compared with the proposal before me and the additional bulk and massing the appeal scheme would add to the property primarily from the change in the roof form, the side extension, given its narrow width and modest roof form in relation to the main roof would be unassuming in terms of the additional bulk and massing it would add to the existing property. I do not therefore consider that more than limited weight in support of the proposal can therefore be added in terms of the side extension not being built out.

In terms of the permitted outbuilding, no further information has been provided and my attention has not been drawn to any reason why the outbuilding could not be erected as shown under the certificate of lawfulness, whether or not the appeal proposal is permitted. This may not be the intention of the appellant were permission for the appeal proposal to be granted, but the lawful certificate for proposed development would endure for future residents. The appellant has not offered any certainty regarding the future status of this outbuilding.

On the basis of the information before me, and notwithstanding the Council’s view on the application of Policy DM43 of the Local Plan, I am not therefore persuaded that weight can be attached to the argument that the volume of increased floorspace as proposed would be less than the volume permitted by both the developments which benefit from certificates of lawfulness, given that it appears that the outbuilding would appear capable of erection in addition to the proposal before me. The argument by the appellant in this respect therefore attracts very limited weight in favour of allowing the proposal.

The lawful development certificates and the appeal proposal before me do not therefore appear to me to be directly comparable with the appeal decision which the appellant has drawn to my attention under the Ref: APP/K0425/D/24/3337174. In that case, the proposal necessitated the removal of an existing outbuilding because a significant part of the new building would be located where the existing outbuilding was positioned. That appeal decision is not sufficiently comparable to alter my reasoning in this case.

The Framework states that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. It goes on to advise 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, is clearly outweighed by other considerations.

The other considerations put forward do not clearly outweigh the substantial weight that I give to the harm to the Green Belt, by reason of inappropriateness and the additional harm to openness. Consequently, the very special circumstances necessary to justify the development do not exist. The proposal would conflict with the development plan and the Framework, when taken as a whole and there are no other material considerations to outweigh that finding.

For the reasons given above, I conclude that the appeal should be dismissed.