Appeal 3325103

The appeal is allowed, and planning permission is granted for the erection of a part single-storey and part two-storey front and rear extensions; the erection of a front open porch and relocation of the entrance door; a new internal staircase, chimney stack and rear balcony; a loft conversion including rear dormer windows and associated works; internal alterations and changes to the fenestration at [site address] , Rickmansworth, [postcode] in accordance with the terms of the application, Ref 23/0570/FUL, dated 4 April 2023, and the plans submitted with it, subject to the following conditions:

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

The development hereby permitted shall be carried out in accordance with the following approved plans: Location plan & block plan - Drawing reference 1416/P2/3 and Proposed plans & elevations - drawing reference 1416/P2/2.

Unless specified on the approved plans, all new works or making good to the retained fabric shall be finished to match in size, colour, texture and profile those of the existing building.

Before the first occupation of the extension hereby permitted the first floor side windows shall be fitted with purpose made obscured glazing and shall be top level opening only at 1.7m above the floor level of the room in which the window is installed. The windows shall be permanently retained in that condition thereafter.

An application for an award of costs has been made by [name] against Three Rivers District Council. This matter is the subject of a separate

Planning permission1 was given for a range of extensions to the dwelling last year (The approved scheme). These are similar, but smaller, than those proposed in this appeal. I see no reason in the evidence why these would not be implemented should no further planning consents be forthcoming and therefore the previous approval represents an important fall-back position.

The main issues are whether the proposed extension would be inappropriate development in the Green Belt, having regard to the National Planning Policy Framework (The Framework) and any relevant development plan policies, the effect on the openness of the Green Belt, and if the proposal would be inappropriate development, whether any harm is clearly outweighed by other considerations, so as to amount to very special circumstances to justify it.

The appeal site is within the Green Belt. Paragraph 154, of the Framework, establishes that buildings in the Green Belt would be inappropriate unless they would meet a listed exception. Paragraph 154(c) explains that the extension or alteration of a building would not be inappropriate provided that it would not result in a disproportionate addition over and above the size of the original dwelling. It appears that the existing dwelling is unaltered from its original construction and therefore is the ‘original building’ for assessment purposes.

Policy CP11, of the [name] 2011 (CS), establishes a general presumption against inappropriate development in the Green Belt. The policy seeks to resist development in the Green Belt that would not preserve its openness or would conflict with the purpose of including land within it. Furthermore, policy DM2, of the Council’s Development Management Policies (DMP), relates to development in the Green Belt that should be in accordance with the Framework. In terms of extensions, policy DM2(b) states that extensions that are disproportionate in size to the original building will not be permitted. It also states that the building’s proximity and relationship to other buildings, its prominence and effect on the openness of the Green Belt, will be taken into account.

National and local policies do not define what is meant by ‘disproportionate’. However, the Council refers to supplementary guidance ‘extensions to dwellings in the green Belt’ SPD [2003]. This identifies that extensions that result in a cumulative increase in floorspace of more than 40% of the original dwelling would be deemed as disproportionate. Nonetheless, this guidance has been superseded by DMP policy DM2. Therefore, although this guidance provides some useful advice on this issue it is dated and only refers to increases in floorspace. It therefore fails to identify that matters such as volume, height and position could affect the proportionality of an addition. This 1 Planning application reference: 22/1761/FUL guidance is therefore of limited weight in my assessment of the proposal. Therefore, considerations of proportionality would be a matter of planning judgement.

The dwelling is a large two-storey detached property that stands within spacious grounds, in a linear row of dwellings, within a rural setting. The plot is enclosed by trees and hedging that provides partial screening to neighbouring plots and the wider countryside.

Main parties agree that the dwelling has an existing floorspace of 334sqm. The Council finds that the proposed extensions would create a new floorspace of 247sqm, amounting to an increase of 74%, with 32% of the increase being within the roof space. The proposed crown roof was not part of the previously approved scheme and would, in comparison to the approved scheme, result in the addition of further bulk and overall mass to the roof-form.

The proposed rear extensions and other alterations, below the eaves line, would result in a floorspace increase of 42%. This would not be materially different to the approved scheme and would not, by itself, result in additions that would be disproportionate to the original dwelling. The proposed roof alterations would result in a slight increase in the existing roof pitch to create increased internal volume, and by the addition of a small crown roof. The crown roof would be incorporated into the middle of the roof and would be surrounded by a hipped roof. Consequently, the hipped roof style of the dwelling would be retained and would remain a predominant feature of the roof. As such, the proposed crown roof, and other roof alterations, would have a minimal impact on the overall bulk of the roof.

The proposed rear dormers would be small, discreet features, limiting their impact on the appearance of the roof shape. The additional floorspace, in comparison to the approved scheme, would be largely created within the existing roof void. This increase would therefore have a minimal effect on the overall mass of the roof and building. Moreover, the Appellant demonstrates that the proposal would amount to a volumetric increase of 44%. This would be far less than the Council’s floorspace calculation and represents a cumulative increase that would be subservient to the original building.

Furthermore, the property is within a staggered row of dwellings. Its rear elevation is relatively well screened from wider views despite the elevated position of the dwelling with respect to its rear outlook. The dwelling is also set slightly ahead of both neighbouring dwellings. This means that in extending to the rear, most of the proposed increase in volume would be screened from the street. The front gable addition is comparatively small and would complement the existing dwelling in design terms. Taking the volume of the proposal, its relationship to the existing building, the surrounding topography and built context into account, the proposed additions would not be disproportionate to the size of the original dwelling.

Consequently, the proposal would comply with paragraph 154(c) of the Framework and would not amount to inappropriate development in the Green Belt. Accordingly, the proposal would accord with CS policy CP11 and DMP policy DM2 for the above reasons. By virtue of being not inappropriate development, the proposal would not be regarded as being harmful to the openness of the Green Belt nor would it require to be justified by very special circumstances.

It is necessary to apply conditions, in connection with a commencement period and list the approved plans, for clarity and to accord with the Planning Practice Guidance [1 and 2]. It is also necessary for a condition to be imposed that requires materials to match the existing dwelling in the interests of the character and appearance of the area [3]. Further a condition is required to ensure that side windows are fitted with obscure glazing in the interests of the privacy of adjoining neighbouring occupiers [4]. The Council has also sought a condition to prevent the addition of further side windows. However, such a condition would be unnecessary as the proposed rooms would receive adequate light from the proposed openings and a requirement to create more windows would be unlikely.

There are no material considerations that indicate the application should be determined other than in accordance with the development plan. For the reasons given above, I therefore conclude that the appeal should be allowed.