Appeal 3325092

The appeal is allowed and planning permission is granted for an outrigger dormer extension and alterations to existing building at [site address] in accordance with the terms of the application, Ref 23/1124/HSE, dated 15 March 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: P22-102.1, P22-102.2, P22-102.3

The materials to be used in the construction of the external surfaces of the development hereby permitted shall match those used in the existing dwelling.

The extension hereby permitted shall not be occupied until the window in the side elevation has been fitted with obscured glazing, and no part of that window that is less than 1.7 metres above the floor of the room in which it is installed shall be capable of being opened. Once installed the obscured glazing shall be retained thereafter.

There is one main issue which is the effect of the proposed outrigger dormer on the character and appearance of the host dwelling and the surrounding area.

The appeal dwelling is a large, traditional, end of terrace house. It has been extended in the past with a large box dormer which occupies most of the rear roof slope. The dwelling has a flat roofed two storey rear outrigger. The proposal is to extend over about half the depth and most of the width of this outrigger to provide an additional bedroom. The extension, which is described as a dormer, would be similar in design and finish to the existing box dormer but would be set at a lower level to reflect the lower roof height of the outrigger.

The appeal dwelling is one of four similar properties all of which have flat roofed two storey outriggers. Most other dwellings in [address] appear to have outriggers with shallow pitched roofs. However, flat roofed outriggers could be seen from the appeal site on the rear of properties in [address] which backs onto the site.

A significant number of dwellings in both [address] and [address] have been extended at roof level. Most extensions comprise large box dormers on the main rear roof slopes. Some include a further extension over the outrigger. In addition to the appeal dwelling, two of the other dwellings in the appeal terrace have large box dormers but none have an outrigger extension. From the appeal site I could see in [address] a number of extensions over outriggers, including those with flat roofs. Moreover, it is clear from the evidence that elsewhere in [address] but not visible from the appeal site there are a significant number of outrigger extensions. These appear to be over shallow pitched roof outriggers.

The box style design of the proposed extension, its position over the outrigger and its projection above the eaves of the main roof of the dwelling would mean it would not be sympathetic to the character or appearance of the original house. I therefore agree with the Council that, notwithstanding an improved arrangement of windows in the existing dormer, the proposed extension would not represent a high quality of design. Nevertheless, taken in the context of the existing box dormer and other roof extensions in the surrounding area and visible from the appeal site, the proposal would not be out of keeping. I have no evidence that any of these other extensions are unlawful and although some appear to have been built under permitted development rights they clearly contribute to the character and appearance of the area.

The Council points out that none of the other dwellings in the adjoining terrace have outrigger extensions. However, the evidence demonstrates that similar, if smaller, extensions could be built under permitted development rights on similar flat roofed outriggers. The terrace is not therefore immune from this type of development, regardless of the outcome of this appeal. Moreover, the roofscape is already disrupted by the existing large box dormers.

The Council makes a distinction between outrigger extensions where the roof is flat as opposed to being pitched. However, I consider that where pitched roofs are shallow, as is the case for many in the vicinity of the appeal site, there is little difference in terms of the effect of an outrigger extension, since in either case the extension projects noticeably above the ridge of the original roof such that its boxy shape is prominent. 2

Overall, I conclude on the main issue that whilst the proposed extension would further alter the character and appearance of the original dwelling, its set in from the end of the outrigger would ensure it was not visually obtrusive and since it would be in keeping with the existing box dormer, any harm to the host dwelling would be limited. Moreover, it would not cause material harm to the character or appearance of the surrounding area. 10.In terms of the development plan, there would be no conflict with Policy D3 of the London Plan, 2021 or Policies CS1 and CS5 of Barnet’s Local Plan ([name]), 2012. These are strategic policies and although they expect local context and distinctive local character to be respected, the proposed extension would comply with this. Turning to Policy DM01 of Barnet’s Local Plan (Development Management Policies), 2012, whilst this requires high quality design, it also suggests that proposals should be based on an understanding of local characteristics and should preserve or enhance local character. Therefore, although there would be conflict with the design aspirations, there would be limited conflict with the objectives of the policy, given the particular circumstances. Finally, there would be conflict with guidance contained in the Council’s Residential Design Guidance, SPD, 2016, with regard to scale and proportion. 11.Balanced against the specific design conflict with Policy DM01 is the fact that the proposed extension would not be out of keeping either with the existing host dwelling or in the context of the surrounding area and would thus comply with policies which seek to respect local context and character. Given this lack of harm, I consider that material considerations indicate that a decision that is not wholly in accordance with the development plan should be reached and that the appeal should be allowed. 12.Turning to conditions, the Council suggests three conditions in addition to the statutory commencement condition. I agree that the development should be carried out in accordance with the approved plans and in materials that match the existing building for the avoidance of doubt and to protect the character and appearance of the host dwelling and surrounding area. Thirdly, to provide certainty, I agree that a condition should be imposed to ensure that the side facing window shown as being obscure glazed is built as such and that the obscure glazing is thereafter retained in order to protect the privacy of neighbouring occupiers. 13.Third parties raise issues regarding overlooking and loss of light and outlook. However, I agree with the Council that the proposed extension would not result in a greater degree of overlooking to the rear and, owing to its limited height and depth and the relationship between the proposed extension and the adjoining properties, no material loss of daylight or sunlight would occur. 14.For the reasons set out above and having regard to all other matters raised, I conclude that the appeal should be allowed.