Appeal 3348791

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 site is located in a rural location with open countryside surrounding the appeal dwelling and its closest neighbours. It lies in the Green Belt. The site comprises a semi-detached house on an extensive plot. It is set well back from [site address] . There is woodland and a modern industrial-type building associated with a farm to the rear. There are scattered dwellings in the vicinity of the dwelling and its semi-detached pair.

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 GB2 and GB13 of the Chiltern District Local Plan (LP), 1997, (including alterations adopted on 29 May 2001) consolidated September 2007 & November 2011, are broadly consistent with the NPPF insofar as they seek to protect the Green Belt from inappropriate development unless very special circumstances exist. The limited extension and alteration of dwellings is supported provided they are subordinate to the size and scale of the original dwelling as it existed on 1 July 1948.

The original dwelling was a small cottage with a floor area that the Council estimates to have been about 105 sqm. A large two storey side and front extension was permitted in 1990. This added about 94 sqm, resulting in an increase in floor area of some 89%. The appellant does not disagree with these estimates.

The current proposed extension would add around 45 sqm of floorspace which would take the cumulative increase in floor area to around 132% above that of the original cottage. The Council’s policies do not define what would be considered disproportionate additions but in my view a cumulative increase that more than doubled the size of the original dwelling could not be described as either limited or subordinate. Moreover, although the proposed extension would be relatively modest in itself, the dwelling already appears substantially larger than the original cottage. Taken together, the increases would therefore amount to disproportionate additions over and above the size of the original dwelling.

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 is set well back from [site address] . The proposed extension is single storey and to the rear and so would not be visible from the lane or from other public places. Whilst the extension would, as a matter of fact, have a small effect on the spatial openness of the Green Belt, it would have no material effect on its visual openness owing to its sympathetic design, position to the rear of and closely associated with the host dwelling, and its limited visibility from beyond the site. It is therefore concluded on the second main issue that the proposed development would result in minor 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 adds weight against the proposals.

The appellant draws my attention to a number of other considerations which she considers might amount to the very special circumstances necessary to justify the development. Firstly, that the extension cannot be considered as overdevelopment owing to its size, position to the rear and in line with the neighbouring extension at No 2, screening and the overall plot size. Moreover, it has been designed to improve the functionality of the dwelling. However, under Green Belt policy an extension is assessed cumulatively with other extensions and overall, taken together with the earlier extensions, it would result in disproportionate additions to the original modest cottage. This consideration therefore carries little weight.

Secondly, other dwellings nearby, including No 2 (the adjoining neighbour) and the adjacent Nos 3 and [address] [name], have been substantially enlarged. However, I have limited details regarding extensions to other dwellings nearby and no knowledge of when they were permitted or whether very special circumstances existed to justify the development. In any case, each development must be judged on its own merits. These other examples therefore carry limited weight.

Thirdly, a single storey rear extension is a common form of development and if the depth of the extension had been limited to 3m across the rear of the original dwelling it would be permitted development (PD). That may be so. However, the extension before me is some 3.6m deep and extends across the full width of the extended cottage. The smaller PD fallback therefore carries modest weight.

Finally, the extension has been judged purely on percentages and the fact that there are no other effects has not been taken into account. However, the starting point for assessing extensions in the Green Belt is whether they would amount to disproportionate additions. Percentage increases can be a useful indicator but, as set out above, a qualitative assessment in this case draws the same conclusion. Since any harm to the Green Belt carries substantial weight, the lack of other harms, which would be neutral, cannot outweigh the harm to the Green Belt arising by reason of inappropriateness and harm to openness. This argument therefore carries negligible weight.

Accordingly, it is concluded on the third main issue that, in the final balance, the other considerations would not clearly outweigh the total 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] GB2 and GB13 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.