Appeal 3369282

The appeal is allowed, and planning permission is granted for a single storey side extension at first floor level and single storey rear extension at [site address] , Denham, Buckinghamshire, [postcode] in accordance with the terms of the application, [name]/25/0841/FA, subject to the conditions set out in the accompanying Schedule.

The appeal property is a detached dwelling standing alongside a narrow lane fronted by several other dwellings in a verdant setting. The property lies in a designated Green Belt (GB)

Two small extensions are proposed but the Council’s concern is related to the cumulative impact of adding these to the property taking account of earlier extensions or additions to the original building.

Notwithstanding its concern on this aspect, the Council find the proposed development in terms of its design aligns acceptably with the existing property and does not materially affect the surrounding area's character or appearance. Nor does the Council consider that the development would harm the living conditions enjoyed by neighbouring residents. I share the Council’s assessments on these issues.

There have been two recent appeals1 concerned with similar proposals in respect of other dwellings in [address]. They are material to my considerations since they form part of the relevant planning history of the locality. 1 APP/N0410/D/22/3292666 & APP/N0410/D/25/3359702

The main issue is whether the development would be inappropriate development in the GB.

The Framework2 establishes that the construction of new buildings in the GB should be regarded as inappropriate unless one of the specified exceptions applies. These include the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building3.

The Council refers to two development plan policies governing development in the GB, being policies GB1 & GB10 of the South Bucks District Local Plan (DLP). Reference is made in GB1’s explanatory text to the policies’ consistency with Government guidance applying at the time. However, the DLP was adopted over a quarter of a century ago and more than a decade before the Framework was first issued, and the guidance referred to in the DLP’s explanatory text has long been withdrawn.

The Inspector in the earlier of the appeals referred to above found these DLP policies to be inconsistent in some respects with current national policy and could be considered out-ot-date. I share his view on these aspects, for the same reasons. The Framework, and national GB policies, have been subject to revision since the issuing of that appeal decision.

Nevertheless, the development plan policies referred to are still relevant and allow the extension of dwellings within the GB, subject to the extensions, either singly or cumulatively, being of a limited or small scale in relation to the size of the original dwelling and its curtilage. No definition of ‘small scale’ is provided in the body of either policy, but the explanatory text to Policy GB10 provides that where the increase in floorspace of the original dwelling is increased by more than half such increase would not be regarded as small scale.

Both parties have undertaken floorspace calculations on the cumulative extensions carried out thus far to the original building, and the empirical effect of implementing the current proposals. They differ in their respective end results, and the appellant describes the Council’s calculations as ‘totally inaccurate’. Although there is no obligation to do so during a householder appeal, the parties have not, to my knowledge, attempted to find common ground.

No properly dimensioned plans showing the original dwelling or the extensions already carried out and proposed have been provided. I am not therefore able to properly judge the accuracy of either set of calculations. However, the information provided has enabled me to acceptably picture and assess the extent of the original dwelling, and the extensions since carried out, and further visual confirmation was gained at my site visit.

Under the terms of the Framework a planning judgment is called for as to whether the extensions are disproportionate. In this regard I do not equate the term disproportionate with ‘small scale’, as the Council appears to define it. There is no single measure of assessing disproportionality, and it is not necessarily based on 2 The National Planning Policy Framework 3 As defined in the Framework an empirical calculation. As mentioned previously the proposed extension are small in scale, and having regard to what I saw, and taking account of the scale and mass of the original dwelling, including the since demolished structures, I do not consider them disproportionate.

Decisions on planning appeals should be made in accordance with the development plan unless material considerations indicate otherwise. For the reasons already provided, including the relevant local policies’ inconsistencies with current national GB policies and their out-of-datedness, I consider this is a case where the material considerations in the form of the Framework’s national policy and guidance indicate to me that the decision should be primarily based on the latter.

[name] do not regard the proposed extensions as disproportionate additions over and above the size of the original building, I conclude that the proposal is not inappropriate development in the GB in the terms of the Framework, and the appeal therefore succeeds. It follows that the openness of the GB would not be harmed. Moreover, the development is not inconsistent with the thrust of the relevant DLP policies which are not inimical to small scale or limited additions to the original dwelling.

I have considered the Council’s responses on suggested conditions set out in the Questionnaire. I am obliged to impose the statutory condition limiting the duration of the permission. A condition in respect of materials is imposed in the interests of visual amenity. In the interests of certainty, it is necessary that the development is carried out in accordance with the approved plans.

All other matters raised in the representations have been considered, including the views of the Parish Council, who did not object, but none is of such strength or significance as to outweigh the considerations leading to my conclusions.

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: The location plan and [name]: 4059-01; -02; -03; -04; -05 & -06.

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.