Appeal 3326442

The appeal is dismissed.

I observed on my site visit that works have commenced to construct the single storey rear extension pursuant to planning permission granted by the Council in June 2023 (ref. 16016/23). That permission was similar to the proposal now before me, save for the size of the rear dormer which was reduced. The Council have taken no issue with the proposed single storey rear extension, or raising the ridge height, and I have no reason to take a different view here.

The main issue in this case is the effect of the proposed rear dormer on the character and appearance of the host dwelling and wider area.

No. [site address] (No.16) is a two-storey detached house located on the western side of a spur of Knightswood, a residential cul-de-sac. It is proposed to raise the ridge height of the main roof of No.16 and construct a dormer within the rear roof plane, to accommodate a bedroom with Juliette balcony.

The guidance in the [address] Extensions Supplementary Planning Document (2012) (SPD) is that the rear elevation is often less prominent and therefore a larger dormer – generally no more than two thirds of the area of the roof plane – may be acceptable as it would not have such a great impact on the character and visual appearance of the building and its setting. The SPD further states that, in design terms, the scale of a proposed dormer should always be a subordinate feature within the roof plane.

The proposed dormer would have a width of around 7.5m and would only be offset from the edges and eaves of the roof by around 400mm and 450mm respectively. The flat roof design of the dormer continues the ridge of the raised roof and because of this, in combination with its width, it would fill the majority of the roof plane (well over two thirds). It would dominate the roof and rear elevation of its host, and fail to appear as a subordinate addition or feature within the roof plane, contrary to the SPD guidance above.

I observed on my site visit that the proposed dormer would be visible from the road between No.20 and No.22 Knightswood, which are set at right angle to one another on the corner. From this location, because of the orientation of No.16, only the cheek of the proposed dormer would be visible. Despite being wider than the dormer approved in June 2023, I am not convinced that the difference in scale would be particularly discernible from this location. The scale of the dormer would, however, be very visible from the rear of those houses fronting Knightswood to the south-west (notably No.24 and 26 Knightswood), particularly during the winter months. It would further be visible in glimpsed views from the publicly accessible woodland to the rear of No.16.

I therefore find on the main issue that the proposed dormer would cause harm to the character and appearance of the host dwelling and wider area. In addition to the conflict with the SPD guidance referred to above, the proposal would conflict with Policy CG3 of Bolton’s Core Strategy Development Plan Document (2011) because its scale would not be compatible with the surrounding area, nor would it conserve or enhance local distinctiveness. It would further conflict with paragraph 130 of the National Planning Policy Framework which requires that planning decisions ensure that developments, amongst other things, are sympathetic to local character, including the built environment.

For the reasons given above, I conclude that the appeal should be dismissed.