Appeal 3353849

The appeal is allowed, and planning permission is granted for a single storey front infill extension to the existing front porch incorporating a new front entrance door, first floor rear extension to infill the existing balcony, single-storey rear extension with lantern rooflight following the removal of existing conservatory, alterations to windows and doors including installation of new double glazed windows and doors and insertion of a conservation rooflight to front elevation and the removal of the garden shed at [site address] in accordance with the terms of the application Ref 24/2299/HSE, and the plans submitted with it, 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: 1366-PL2-100, 1366-PL2-101 and 1366-PL2-110.

The external materials of the extension hereby permitted shall match those used in the existing dwelling.

I have taken the description of development from the appeal form and decision notice. This is because it is a more accurate reflection of the development for which permission is sought than that given on the application form.

On 12 December 2024 a revised National Planning Policy Framework (the Framework) was issued. In the interest of natural justice and to ensure neither of the main parties were prejudiced by this matter, I consulted both parties on the changes to the Framework, and this has informed my determination of the appeal.

It was apparent that construction on site had commenced, with the appeal property (No 61) differing in its appearance from the submitted ‘[name] and ‘[name]. However, No 61 has an extant planning permission Ref 24/0813/HSE. As there was no first-floor rear extension, I have dealt with the appeal based on the proposed plans that were submitted with the planning application and considered and consulted upon by the Council.

The proposal is for a single storey front infill extension to the existing front porch incorporating a new front entrance door, a first floor rear extension to infill the existing balcony, a single storey rear extension with lantern rooflight following removal of the existing conservatory, alterations to windows and doors including installation of new double glazed windows and doors, the insertion of a conservation rooflight to the front elevation and the removal of the garden shed. The Council has indicated that it has no objection to the single storey front infill extension to the front, the single storey rear extension with lantern rooflight, alterations to the windows and doors, or removal of the garden shed. Based on the evidence, I have no reason to take a different view. The dispute between the parties therefore relates to the erection of a first-floor rear extension.

The main issues are: • whether the proposal would be inappropriate development in the Green Belt, having regard to relevant development plan policies and the Framework and the effect upon the openness; • the effect of the proposal on the character and appearance of the host property and the surrounding area; • whether any harm by reason of inappropriateness, and any other harm would be clearly outweighed by other considerations, so as to amount to the very special circumstances required to justify the proposal.

Policy G2 of the London Plan 2021, Policy CS7 of Barnet’s Local Plan ([name]) Development Plan Document 2012 ([name]) and Policy DM15 of Barnet’s Local Plan (Development Management Policies) Development Plan Document 2012 (DMP) relate to development in the Green Belt. Policy DM15 states, amongst other matters, that development proposals in the Green Belt are required to comply with the Framework. Criterion iv. of Policy DM15 states that extensions to buildings in Green Belt or [name] will only be acceptable where they do not result in a disproportionate addition over and above the size of the original building or an over-intensification of the use of the site.

The Framework states that the essential characteristics of Green Belts are their openness and permanence. Paragraph 154 states development in the Green Belt is inappropriate unless the development falls within the exception list. This includes criterion c) which relates to extensions or alterations of a building and states that such works should not result in disproportionate additions over and above the size of the original building.

The Framework and the development plan provide no specific definition or threshold as to what would amount to disproportionate additions. The Supplementary Planning Document: Residential Design Guidance – October 2016 (the SPD) does however set out a guiding principle that extensions to dwellings within Barnet’s Green Belt should not increase the original volume by more than 25% by external measurement in order to protect openness.

The Council contend that from its analysis of the historic applications and the submitted drawings, the floor area would measure approximately 62% of the original building. However, these calculations only relate to floor area and not volume.

Neither party has provided me with the volume of the original house or a comparison of the proposed extension and previous extensions against said volume. Notwithstanding this, the appellant’s submission does state that the volume of the proposed development would be approximately 19.6 cubic metres and that there would be some volume reduction through the conservatory size and the removal of the shed.

No 61 is a large, detached dwelling set within a long plot. The ground floor extends up to the shared boundary with its immediate neighbour, No 63. The upper floor is set further away which results in a gap in the first-floor building line. The first-floor rear of No 61 is recessed in part which creates a step to the flank and rear elevations. The proposed first floor rear extension would infill the recessed area while continuing the existing flank and rear elevations. Its position, alongside the existing dwelling, would result in a modest increase in floor area which would not significantly increase its bulk.

Even if the Council contend that the cumulative extensions would measure approximately [address] metres, it does not demonstrate that it would increase the original volume by more than 25%. I therefore have no compelling evidence to show that the proposed development would be disproportionate. Ergo, the proposal would not be inappropriate development in the Green Belt.

[name] have found that the proposed development would not be inappropriate, there is no requirement for a subsequent assessment of the effect of the development on the openness of the Green Belt.

For these reasons, and based on the evidence submitted and observations on site, the proposed development would not result in a disproportionate addition over and above the existing dwelling. Consequently, it would comply with [name] and CS7 of the [name], Policy DM15 of the DMP, Policy G2 of the London Plan, paragraph 154 c) of the Framework and the overarching aims of the SPD. Therefore, I conclude that the proposal would not be inappropriate development in the Green Belt.

No 61 is accessed via a private road, set back from [address] and located in an area consisting of low-density housing, with elongated gardens to the rear. I observed a variety of designs and proportions of properties within the immediate area. The main roof to No 61 is predominantly hipped with flat-roofed sections located towards the rear.

As noted above, the proposed extension would continue the flank and rear elevations and retain the separation at the first floor with No 63. Moreover, the roof would also form a continuation of an existing flat roof. Given its location, even if the property has been extended previously, the maintenance of its building lines and retention of the spacing between Nos 61 and 63 would result in the proposed extension not being readily visible from any public vantage points.

I have taken into account the cumulative impact of the proposal, however, in this respect, I have been provided with limited details of previous extensions to the first floor. Given my findings above, I consider that the overall impact would not present any adverse planning issues which would suggest that permission should be withheld.

For the reasons given above, the proposal would not harm the character and appearance of the host property or the surrounding area. As such, it would accord with Policy D3 of the London Plan, Policies CS1 and CS5 of the [name] and Policy DM01 of the DMP which collectively seek to ensure that development respects local context and distinctive local character, creating places and buildings of high-quality design. It would also accord with the SPD which seeks, amongst other matters, for rear extensions not to look too bulky and prominent compared to the size of the main building and garden to which they relate.

Given that the proposed development would not amount to inappropriate development in the Green Belt, there is no need for me to assess other considerations and whether very special circumstances exist in order to justify the development.

In addition to the standard time limit condition, it is necessary to ensure that the development is carried out in accordance with the approved plans for the reason of certainty. In the interests of the character and appearance of the area, a condition relating to matching materials is also necessary.

For the reasons given above the appeal should be allowed.