Appeal 3336885

The appeal is allowed and planning permission is granted for demolition of side utility room extension and erection of single storey rear extension, internal alterations and raising of dormer flat roof at [site address] in accordance with the terms of the application, Ref 23/2254/HSE, dated 21 May 2023, 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: Site location/Block plan, 524823-1, 524823-2, 524823-3 and 524823-4.

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.

There are three main issues. Firstly, whether the proposed extensions would amount to inappropriate development in the Green Belt; secondly, the effect of the proposed extensions on the character and appearance of the host dwelling and the Monken Hadley Conservation Area; and thirdly, the effect of the proposed single storey rear extension on the living conditions of the occupiers at ‘Chalkidons’ with respect to light, overshadowing and outlook.

The appeal site is located in a row of large, detached infill dwellings on the edge of [name]. The land to the front and rear is undeveloped. It lies within the Green Belt and in the Monken Hadley Conservation Area (CA). The site comprises a long and relatively narrow plot. The dwelling was built in 1951 and comprises a two storey house with an original single storey garage on one side and a single storey utility room extension on the other. It is identified in the Monken Hadley Conservation Area Character [name], January 2007, as a very good example of neo-Georgian design. It has been extended to the rear in the past by the addition of a single storey infill extension between an original two storey outrigger and the site boundary. This has a dummy pitched roof.

The proposed development includes the demolition of part of the utility room extension and the dummy pitched roof. A single storey flat roofed extension some 4m in depth would be added to the existing single storey rear extension and would project about 3.5m beyond the two storey outrigger. Finally, the height of an original section of flat roof between the two storey outrigger and a small gable above a window would be increased by about 0.5m to increase headroom on the first floor landing.

The parties agree that the proposed deletions and additions would result in the dwelling being some 27% larger in volume than the original house.

Policy DM15 of Barnet’s Local Plan (Development Management Policies) (DMP), September 2012, requires development proposals in the Green Belt to comply with the Framework. It goes on to say that extensions to buildings in the Green Belt will only be acceptable where they do not result in a disproportionate addition over and above the size of the original building. This accords with the Framework. “Original building” is defined in the Framework as “a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally”. The term “disproportionate” is not defined but Barnet‘s Supplementary Planning Document: Residential Design Guidance (SPD), October 2016, states that “as a guiding principle the volume of the original dwelling should not be increased by more than 25%”. It goes on to say that there may be cases where a greater or lesser increase is appropriate.

It is clear that the SPD does not intend the 25% guideline to be applied in a rigid way and in my view the additional 2% increase would, in principle, lie within a reasonable range of tolerance. Moreover, the proposed extensions, taken together, would remain clearly subordinate to the original dwelling. I consider that, in the context of the original dwelling, they would be modest in scale and would not amount to disproportionate additions over and above the size of the original building.

It is concluded on the first main issue that the proposed extensions would not amount to inappropriate development in the Green Belt. In consequence, there would be no conflict with DMP Policy DM15, Policy G2 of the London Plan (LP), 2021, or with the Framework insofar as they seek to control extensions to buildings in the Green Belt. The Courts have found that where development is found to be “not inappropriate” it should not be regarded as harmful either to 2 the openness of the Green Belt or to the purposes of including land in the Green Belt. I shall therefore restrict my further consideration to the other main issues. The effect of the proposed extensions on the character and appearance of the host dwelling and the Monken Hadley Conservation Area

The Council does not object to the demolition of part of the existing utility room or to the removal of the dummy pitched roof. I agree these would be acceptable. The single storey rear extension would extend the existing rear extension, which has already had a material effect on the appearance of the rear elevation, by an additional 4m. This would exceed the 4 metres which the SPD suggests is normally acceptable for detached dwellings. 10.However, the extension would be, in part, set between the noticeably higher boundary wall with ‘Chalkidons’, a locally listed building, and the two storey outrigger. The projection beyond the end of the wall would be some 2.8m and about 3.5m beyond the outrigger. The two storey outrigger would remain dominant owing to its height, the limited projection and the simple, flat roof of the extension. Moreover, the removal of the dummy roof which is an unsympathetic addition would enhance the overall appearance. Therefore, although the relationship between the various elements would alter, I am satisfied that the combined rear extensions would not appear excessive or harm the character of the dwelling and that the conflict with the SPD would be acceptable in this case. The Council raises concerns regarding the amount of glazing proposed but this would be proportionate to the rear and side elevations and would match the style of existing glazing in the rear of the outrigger. Overall, the single storey rear extension would be a subservient and sympathetic addition to the host dwelling. 11.The Council states that the proposed extension would project further than surrounding rear building lines and that this could set a precedent. However, the evidence suggests that this would not be the case. Moreover, the intervening boundary treatments and plot sizes mean there is limited intervisibility between properties. In any case, each development should be assessed on its own merits as I have done. Finally, the scale of the extension, in the context of the very long rear garden and substantial plots nearby would ensure there was no impression of overdevelopment. 12.The raising of the flat roof between the outrigger and the small gable would be a minor alteration that would be barely discernible. The eaves of the flat roof are already higher than those of the outrigger and the additional height would not materially alter the relationship between the two. Although the proposed roof would cut into the small gable at a higher level this alteration would be readily absorbed and the increase in the height of the oriel window on the stairs would ensure that the relationship between the eave and the window remained in proportion. 13.The proposed extensions would be substantially hidden from ‘Chalkidons’ by the small gable feature and the intervening high boundary wall and close boarded fence beyond. This, the limited projection of the rear extension beyond the wall and the large single storey side/rear projection at ‘Chalkidons’ which lies adjacent to the shared boundary would ensure its setting was preserved. In terms of the wider CA, the appeal dwelling and its grounds have a positive 3 impact. The proposed extensions would not alter this and as such the character and appearance of the CA would be preserved. 14.It is concluded on the second main issue that the proposed extensions would have no materially detrimental effect on the character or appearance of the host dwelling or the surrounding area and would preserve the character and appearance of the CA and the setting of the locally listed building, ‘Chalkidons’. In consequence, they would comply with [name], CS1 and CS5 of Barnet’s Local Plan ([name]) (CS), September 2012 and with Policies DM01 and DM06 of the DMP. Taken together and amongst other things, these expect new development to be of a high quality of design that respects local context and distinctive local character such that it preserves or enhances the character or appearance of heritage assets and their settings, including conservation areas and locally listed assets, and local character through appropriate scale and height. Living conditions 15.‘Chalkidons’ has a flat roofed side extension that abuts the shared boundary and has a similar rear building line to the existing extension at the appeal dwelling. The high boundary wall projects about 1m beyond this and beyond that the boundary is marked by a close boarded fence some 1.8m high topped by dense vegetation. The extension would project about 2.8m beyond the wall. 16.Since ‘Chalkidons lies to the southwest of the appeal dwelling there would be no effect on light and no noticeable overshadowing. Moreover, the limited height, and projection beyond the wall, of the proposed extension, together with the intervening fence, would mean it had no material effect on outlook from ‘Chalkidons’ and would not lead to a sense of enclosure. 17.It is concluded on the third main issue that the proposed rear extension would have no adverse effect on the living conditions of occupiers of ‘Chalkidons’. In consequence, it would comply with CS Policy CS5, DMP Policy DM01, the LP and the SPD. Taken together and amongst other things, these expect extensions to dwellings to be designed so as to allow adequate light and outlook for adjoining and potential occupiers.