Appeal 3356266

The appeal is allowed and planning permission is granted for a part single storey, part two storey rear extension with rooflight at [site address] , Wheathampstead, Hertfordshire, [postcode] in accordance with the terms of the application, Ref 5/24/1423, 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: Site location plan, 5CRO-BP rev 2, 5CRO-GP rev 2, 5CRO-FP rev 2, 5CRO-EV rev 2, 5CRE-BP rev 2, 5CRE-GP rev 2, 5CRE-FP rev 2, 5CRE-EV rev 2, 5CRP-BP rev 2, 5CRP-GP rev 2, 5CRP-FP rev 2, 5CRP-EV rev 2.

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

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 traditional, semi-detached house on a wide plot that tapers to the rear. The dwelling is set on the side of a shallow valley within a sizeable housing estate immediately to the north of the B653 [address]. The estate is surrounded by open countryside and lies within the Green Belt. The dwelling has been extended in the past through a two storey side extension and a two storey front extension. The rear elevation is as built.

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 [site address] 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 Council estimates that previous extensions have slightly more than doubled the floorspace of the original dwelling and that the proposed extensions would add about a further 34m2. Cumulatively, this would increase the floorspace of the original dwelling by some 147%. The increase in volume is estimated to be about 364m3. The appellant does not dispute these 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 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 floorspace increase of over 100%. The proposed extensions would only add to this. Secondly, the type of extension proposed is considered. This would comprise a two storey and single storey rear extension with a hipped roof over the two storey element meeting the existing main ridge. Rear extensions are generally viewed more favourably than side or front extensions and in this case neither would project more than 3m from the original rear elevation. Nevertheless, overall, the extension would add noticeable bulk and have a material effect on the scale of the dwelling.

In terms of visibility from public viewpoints, the side of the two storey extension would be seen in gaps between dwellings from the public highway and would have a modest effect on views of vegetation to the south. However, it would not fill any gaps and in the context of the surrounding built development it would have a limited visual impact on the locality.

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 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 well to very well, with the main detractor being the existing enlargements. This would indicate that figures at or above the top of the ranges or maximum set out in Table 2 of the SPG would be appropriate. Nevertheless, even allowing that these should be applied flexibly, the proposed extensions, taken together with previous additions, would result in a dwelling that was considerably bigger than the original dwelling. In consequence, whilst relatively modest in themselves, in combination with existing extensions they 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 on an established housing estate and the extensions would be to the rear of the host dwelling. It would thus have a very small effect on the visual openness of the Green Belt which is already characterised by built development in the vicinity. Nevertheless, it would, as a matter of fact, owing to its size have a discernible spatial effect. This would be limited by its close association with the host dwelling, and the neighbouring dwelling which has been extended to the rear at ground and first floor in the past. Overall, the proposed extensions would have a minor effect on Green Belt openness.

It is 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 weighs against the proposed development.

The appellant draws my attention to one main other consideration which he considers might amount to the very special circumstances necessary to justify the proposal. This is a fallback position under which very similar extensions to those proposed could be built, it is alleged, under PD rights. The matter was considered in an earlier appeal (APP/B1930/D/23/3329521) but was given limited weight because the Inspector could not be sure whether the rear elevation had already been altered and thus whether the fallback was realistic. The appellant has now submitted original drawings for the dwelling showing that the rear elevation remains as built. This uncertainty therefore no longer exists.

However, the Council raises a new matter in the context of this appeal, suggesting that the proposed gap between the PD two storey extension and the single storey element would be insufficient to meet the limitations set out in Schedule 2, Part 1, Class A of the Town and Country Planning (General Permitted Development) Order 2015 (GPDO) that the extensions must not be joined. Plans submitted to illustrate the fallback option clearly show two extensions with a small gap and the appellant argues that “joined” should take its ordinary and natural meaning. I have some sympathy with that view. However, the matter has not been tested through the courts. Moreover, the Council considers the gap to be de minimus and cites various appeal decisions in support. These indicate that various Inspectors have taken the view that gaps of 50mm or less are not material and would not comply with the GPDO.

The appellant has countered this view by drawing my attention to other appeal decisions where a gap of 300mm or more has been found to be material.

The gap shown on the appellant’s plans which were submitted with the application is clearly less than 300mm. However, [name] of the Statement of Case for the appeal illustrates various alternative designs which, the appellant suggests, would be PD, even if the proposal with the smaller gap was not. The Council does not suggest that either of the two extensions on their own would not be PD. Of the alternative designs, the appellant points out that the proposed two storey extension would be offset from the shared boundary with No 3, the attached neighbour, by some 2.9m but that under the GPDO it could come within 2m, thus resulting in a larger two storey extension and a small, unbuilt gap between it and the single storey rear extension at No 3. This appears to be correct.

Alternatively, a narrower single storey extension could be built with a larger gap of 500mm between it and the two storey extension. Whilst this would result in a smaller room, I consider it would still provide useable internal space and the gap would be readily apparent. This also appears to fall clearly within PD limitations.

The issue remaining is therefore whether the PD fallback would result in extensions that were equivalent to or worse than the appeal proposal in terms of their effect on the Green Belt. In my view, the 500mm gap in the PD alternative would have no discernible effect on the Green Belt. The difference in size of the extensions would be negligible in this regard and the gap would be insufficient to have any material effect on openness. This option would thus have equivalent effects. The wider two storey extension, by contrast, would result in additional built development at first floor which would be seen from neighbouring gardens and visibly reduce openness. By contrast, the gap left by not building a single storey extension would have a negligible effect owing to its small size, and position hidden between other built development. This option would therefore have a slightly worse effect on the Green Belt than the appeal proposal.

The appellant also refers to other considerations such as other extensions nearby, the lack of other harms and personal circumstances. These add little weight in favour of the development.

Nevertheless, in view of the realistic fallback position, it is concluded on the third main issue that, in the final balance, the other considerations would 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 have been demonstrated. The proposed development would therefore comply with [name] 1 and 13 and with national policy set out in the NPPF, 2024.

Turning to conditions, the Council suggests two conditions in addition to the statutory commencement condition. I agree that the development should be carried out in accordance with the approved plans to provide certainty and that it should be built in matching materials so as to protect the character and appearance of the host dwelling and the surrounding residential area. I agree that no other conditions would be necessary.

For the reasons set out above and having regard to all other matters raised, including the lack of objection from the Wheathampstead Parish Council, I conclude that the appeal should be allowed.