Appeal 3349461

The appeal is dismissed.

The main issues are: firstly, whether the proposed development would amount to inappropriate development in the Green Belt, having regard to the National Planning Policy Framework (NPPF), 2024, and any relevant development plan policies; secondly, the effect on the openness of the Green Belt; and thirdly, if the proposed development would amount to inappropriate development, whether the harm by reason of inappropriateness and any other harm is clearly outweighed by other considerations, such as to amount to the very special circumstances necessary to justify the development.

The appeal dwelling is a large, detached house on an extensive plot, set in an elevated position on the side of a shallow valley. It lies in open countryside and within the Green Belt. The house has one near neighbour, also set on an extensive plot and overlooking the valley. The dwelling has been extended in the past through a large two storey side extension and a smaller single storey rear extension. It has an original attached single storey annexe that is understood originally to have been a garage.

The NPPF identifies that the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open. It goes on to state that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. For extensions and alterations to buildings, these should not result in disproportionate additions over and above the size of the original building. “Original building” is defined in the NPPF as a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as originally built.

Policies 1 and 13 of the City and District of St Albans District Local Plan Review (LP), adopted 1994, taken together are broadly consistent with the NPPF insofar as they seek to apply national Green Belt policy to protect the openness and character of the Green Belt. The limited extension of existing dwellings is supported provided it is modest in scale so as not to create a significantly larger building, visually well integrated with the rural surroundings, has no significant impact on the character and appearance of the countryside and does not harm the ecology, natural beauty or amenity of the countryside. The Council’s Supplementary Planning Guidance: Residential extensions and replacement dwellings in the Green Belt (SPG), 2004, provides guidance on what may represent disproportionate additions.

The floor area of the original building is disputed between the parties but there is broad agreement that the resultant building, including existing and proposed extensions would have a floor area of around 535m2. The appellant estimates this would amount to an increase of some 107% over the size of the original building and the Council suggests about 81%. The difference appears to arise because the Council estimates the original dwelling to have been larger than the appellant’s estimate. In terms of volume there is broad agreement that the increase would be between 660m3 and 671m3, amounting to an increase over the original building of about 103%.

The Council also refers to an outbuilding “in close proximity” to the dwelling that was granted a Lawful Development Certificate (LDC) and which, it suggests, could be included as an extension. However, it is not clear which structure is being referred to. A modest orangery extension that was granted an LDC with a floor area of some 14m2 exists to the rear of the dwelling but the outbuildings I saw, with the exception of a small summerhouse, were some distance from the dwelling and could not, in my view, be considered to be “extensions”. If the orangery is added to the size of the dwelling the difference in percentage increase would be small and lie within the range between the Council’s and appellant’s figures.

In terms of size, the SPG provides guidelines on size ranges for extensions which might be acceptable of between 20% and 40% increase in floor area and up to 300m3 in volume. The SPG makes clear that these are not rigid limits and the Council’s main concern is to ensure that other criteria in the SPG are complied with. Moreover, the guidelines were established to take account of Permitted Development (PD) rights limits which applied at the time but which have since been removed. In general, larger extensions are now permitted as PD and therefore the Council’s guidance should be applied flexibly.

The Council’s SPG sets out seven further criteria against which extensions should be judged. The performance of the extensions against these then provides a guide as to what scale of extensions, within the range set, may be considered not to be disproportionate. I shall consider these in turn.

Firstly, it is agreed that previous extensions have already enlarged the dwelling significantly with a volumetric increase of over 100%. The proposed extensions would only add to this. Secondly, the type of extension proposed is considered. This would comprise a first floor side and roof extension above an existing attached annexe and the infilling of the gap above ground floor between the annexe and the main dwelling. Although not increasing to building’s footprint, the extension would noticeably increase the width at full height of the rear elevation of the dwelling. Moreover, the eaves would be raised to a level above the eaves of the main dwelling. Overall, the extension would add conspicuous bulk and have a material effect on the scale of development in an open location.

In terms of visibility from public viewpoints, the extension would be seen clearly from the south-west, especially through gaps in the vegetation from the designated surfaced cycle route that runs along the valley to the south-west of the site. I saw during my site visit on a weekday that this is a well-used route. There would also be glimpsed views from [site address] and [address], especially during winter months. The overall increase in bulk and height in an open location would therefore result in a noticeably greater impact on the wider landscape. This effect would be exacerbated by the infilling of the gap between the existing annexe and the main dwelling, up to main ridge height, which would consolidate the built form, adding to the impression of bulk and reduction in openness.

Turning to the other SPG criteria, I agree with the Council that there would be no conflict with LP Policy 72 which is a design policy that applies to all extensions. Further, since no landscaping or trees would be affected (and some additional boundary planting is proposed), and the site is neither a listed building nor within a Conservation Area the proposed extension would have no adverse effect on these.

Taking account of the SPG criteria as a whole, the proposed extensions perform moderately. This would indicate that figures towards the bottom of the range should be considered. Even allowing that these should be applied flexibly, owing to the age of the SPG and the reasoning behind the limits set, I consider that the proposed extensions which would result in a dwelling that appeared noticeably bigger and result in a cumulative increase in floorspace of between 81% and 107% and a more than doubling of volume could not be described as modest in scale and would result in disproportionate additions to the original building.

It is concluded on the first main issue that the proposed development would amount to inappropriate development in the Green Belt. The NPPF advises that substantial weight should be given to any harm to the Green Belt, including that by reason of inappropriateness.

The NPPF states that the essential characteristics of Green Belts are their openness and permanence. Openness has a spatial and visual aspect. The appeal property lies in an elevated and visually prominent position in open countryside. The proposed side extension at first and second floor would add height and bulk which would be clearly visible from the large garden of the dwelling and from the surrounding open countryside. This would have a noticeable effect on both spatial and visual openness.

It is concluded on the second main issue that the proposed development would, result in moderate harm to the openness of the Green Belt. The NPPF makes clear that substantial weight should be given to any harm to the Green Belt and the loss of openness therefore weighs heavily against the proposed development.

The appellant draws my attention to a number of other considerations which he considers might amount to the very special circumstances necessary to justify the proposal. Firstly, he refers to a material change in circumstances since the previous appeal (APP/B1930/W/23/3322966) was dismissed in 2023, namely that the proposed extensions have been significantly reduced in scale through the removal of large roof extensions including dormer windows, such that the current proposal would increase the floorspace by just under 20% of the existing floorspace. This, he suggests is marginal. In addition, there is no objection on design grounds. [name] agree that the current proposal is noticeably smaller, the extensions must be judged against the original dwelling and not the previously refused scheme. Since the dwelling has already been significantly enlarged, I do not agree that a further 20% increase would be marginal. The lack of any objection to the design only slightly mitigates the harm by reason of inappropriateness. This matter therefore carries limited weight.

Secondly, additional landscaping is proposed on the south-west boundary of the property. However, owing to the elevated position of the dwelling above the boundary I am not persuaded that this would mitigate against visual harm to openness for many years and it would have no material effect on the spatial loss of openness. I therefore afford this matter little weight.

Finally, it is suggested that there would be an economic benefit from the construction of the extension but since this is a circumstance that would apply to any development, I do not consider it unusual or that it carries any material weight in favour of the proposed development.

Accordingly, it is concluded on the third main issue that, in the final balance, the other considerations would not clearly outweigh the harm to the Green Belt through inappropriateness and loss of openness. Consequently, the very special circumstances necessary to justify the development do not exist. The proposed development would therefore conflict with [name] 1 and 13 and with national policy set out in the NPPF, 2024.

For the reasons set out above and having regard to all other matters raised, I conclude that the appeal should be dismissed.