Appeal 3361585

The appeal is allowed and planning permission is granted for the erection of a roof extension with dormer windows and a single storey rear extension, following demolition of existing single storey extension, at [site address] in accordance with the terms of the application Ref. 24/P/01646 and the plans submitted with it, subject to the conditions set out in the attached Schedule.

The main issues are whether the proposed extensions constitute ‘inappropriate development’ in the Green Belt; the effect on its openness; and, if inappropriate development, whether this is clearly outweighed by very special circumstances.

The appeal site comprises a detached bungalow set in a large garden in a ribbon of development where there is a mixture of houses ranging from large two storey houses to relatively small single storey properties. Although a bungalow, the property has accommodation in the roof space lit by three small dormer windows on the rear elevation. The site lies in the Green Belt; the Surrey Hills National Landscape; and an Area of [name] (AGLV).

The National Planning Policy Framework (NPPF) sets out in paragraph 153 that new development in the Green Belt is inappropriate and should not be approved except in very special circumstances. Paragraph 154 sets out the categories of development which are regarded as exceptions and are not inappropriate. The relevant one to this case is (c) regarding the ‘extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original dwelling”. The term ‘original dwelling’ is defined in the Glossary as the building as it existed on 1st July 1948, or if constructed after that date, as it was built originally.

Policy P2 of the Guildford Borough Local Plan: Strategy and Sites (LPSS) mainly restates the NPPF policy, however the related Supplementary Planning Document 2023 (SPD) gives guidance on the interpretation of national and local policy on Green Belts. In terms of the extension or alterations of a building the guidance indicates that the LPSS does not define a particular floorspace or volume percentage increase which may be considered ‘disproportionate’, but suggests a series of factors which will need to be considered along with an increase in floorspace.

In this case the main parties agree that the dwelling was constructed following the grant of permission in 1955. That original dwelling had a floor area in the region of 117sqm. However, there have been a number of permissions for additions since that time as set out in the officer report, but not all of these have been implemented in full. I understand that the existing dwelling has a floor area of about 180sqm and the proposal would add a net increase to about 274sqm which the Council indicate would be a 135% increase from the original property.

However, the appellant has obtained a Certificate of Lawfulness for the addition of a rear single storey extension of about 62sqm as ‘permitted development’ under ref. 24/P/00915. This proposal also includes provision for the erection of a detached outbuilding. Nevertheless, from the information available it appears to me that the outbuilding would be sited too far from the property for it to be part of the assessment taking account of the judgement in Warwick1.

The appellant claims the permitted extension is a fallback position which would have a similar effect on the appearance of the property and on the openness of the Green Belt as the rear element of the proposed scheme. On the evidence submitted it appears to me that this fallback is a material consideration and that there is a reasonable prospect of the addition being constructed rather than it being just a theoretical point. It is therefore reasonable to take that addition into consideration in the floorspace assessment.

Taking account of the scale of lawful extension that may be added, the appellant’s calculations show that the total with the original is in the region of 235sqm (not including the permitted outbuilding) compared to the floorspace proposed in the appeal scheme at 266sqm.

The SPD recognises that relying on floorspace alone is an oversimplification of the issue. It is appropriate to take into account the changes in building volume as that is more likely to have an effect on openness. With the demolition of the existing side extension, the appellant calculates that the external volume of the original plus the permitted development scheme would be about the same as the appeal scheme although this assessment also takes account of the outbuilding.

In terms of the mass of building at the property itself there would be a reduction in the width of the building with the demolition of the side extension, Moreover, although the roof ridge would be raised by about 1.1m I do not see that as being material to the overall bulk of the building as both the permitted and proposed extent of roof accommodates dormer windows front and back. 1 Warwick District Council v Secretary of State for [name] , Housing and Communities [2022] EWHC 2145 (Admin)

The appeal proposal is also of a modest and reasonable scale relative to the size of the plot and the demolition of the side extension would improve the perception of openness around the property and especially in the wider gap to the southern side boundary.

Finally, based on the appellant’s comparative drawings of existing and proposed elevations, I find that the visual perception between the original dwelling, as extended and with some demolition, and the appeal scheme would not appear significantly larger in the overall context of the site.

Taking all of these comparisons into account I conclude that the appeal scheme is within the flexibility envisaged in the SPD and the additions would not result in disproportionate additions over and above the size of the original property as set out in paragraph 154(c) of the NPPF. As such the proposal is not ‘inappropriate development’. Given this conclusion I do not need to consider separately the effect on openness or whether very special circumstances apply.

Overall, I find that the proposal accords with the provisions of Policy P2 of the LPSS, and the NPPF when this is read as a whole, and this outcome is not outweighed by any other consideration. The appeal should therefore be allowed.

The Council recommends that three standard conditions be imposed concerning the commencement of the development; accord with the submitted plans; and external materials to match the existing building. These conditions are necessary to define the permission; for clarity; and to ensure that the overall appearance of the enlarged property is appropriate to maintain the character of the area, and I will impose them

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

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

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. 3 The development hereby permitted shall be carried out in accordance with the approved plans – [name] 1, 2, 3, 4, 5, 6, 7, 11, 13, 14 and PO3, dated 25 October 2024.