Appeal 3335951

The appeal is allowed and prior approval is granted under the provisions of Article 3(1) and Schedule 2, Part 1, Class AA of the Town and Country Planning (General Permitted Development) (England) Order 2015 (as amended) for an additional storey above the existing dwellinghouse at [site address] , Hertfordshire [postcode] in accordance with the terms of the application, Ref 6/2023/1772/PN27, and the plans submitted with it.

The Council determined that the appeal proposal would not meet the limitation in [name].1.(i) of Class AA of the GPDO, which states that development is not permitted by Class AA if, amongst others, any additional storey is constructed other than on the principal part of the dwellinghouse.

In assessing the effect of the appeal proposal on the external appearance of the building, the Council has, under [name].3.(3)(a) of Class AA of the GPDO, concluded that even if the appeal proposal was permitted development, it would not comply with the condition in [name].2.(3)(a)(ii) of Class AA of the GPDO, and it refused prior approval.

The condition in [name].2.(3)(a)(ii) of Class AA of the GPDO, requires the developer to seek prior approval from the local planning authority as to the external appearance of the enlarged dwellinghouse, including the design and architectural features of (aa) the principal elevation of the dwellinghouse, and (bb) any side elevation of the dwellinghouse that fronts a highway.

Based on the preliminary matters above, the main issues in this appeal are: • Whether the proposal would be permitted development, with particular regard to the limitation in [name].1.(i) of Schedule 2, Part 1, Class AA of the GPDO, and • If the proposal is permitted development subject to prior approval, whether prior approval should be granted under Article 3(1) and Schedule 2, Part 1, Class AA of the GPDO, having particular regard to the effect of the proposed development on the external appearance of the building.

[name] AA4.(1) clarifies that for the purposes of Class AA, the “principal part” in relation to a dwellinghouse means the main part of the dwellinghouse excluding any front, side or rear extension of a lower height, whether this forms part of the original dwellinghouse or is a subsequent addition.

The planning history records listed by the Council indicate that the existing dwellinghouse of [site address] comprises of previous additions that have increased its size. However, for the purposes of [name] AA4.(1), subsequent additions to the existing dwellinghouse are not excluded from the definition of the “principal part”, unless they are lower in height. As such, under this part of the GPDO, the originality of the existing dwelling is not determinative to my considerations.

[site address] comprises of a main ‘core’ under a taller main roof form with a comparatively long roof line, and asymmetric front and rear slopes. Despite the shallower pitch of the roof slope above the sitting room, this main core has a clearly identifiable singular visual mass by comparison to the several lower height wings of a smaller scale and mass that project from it, consisting of front wings, rear wings joined by a central flat roof, and a flat roofed side wing.

Under the definition in [name] AA4.(1), I find that the main core of [site address] with its singular mass is clearly identifiable as the “principal part” of the dwellinghouse, and therefore the lower height projecting wings are excluded from this definition. It is clear from the drawings that the proposed additional storey would be constructed ‘on’ this principal part of the dwellinghouse and not on any of the lower height wings of the dwellinghouse comprising of front, side or rear extensions whether original or not.

Consequently, I conclude on this issue that the proposed development would comply with the limitation in [name].1.(i) of Schedule 2, Part 1, Class AA. It is not a matter of dispute between the main parties that the proposal complies with all other limitations and restrictions in [name].1 of Class AA of the GPDO. Based on the evidence before me, I have no reason to reach a different view. As such, it is permitted development subject to prior approval.

[site address] is set well back from the road within a mature and generous plot, and behind numerous sizeable trees. Even when not in leaf, those trees would be expected to markedly filter views of it from the road and surrounding properties, and it is not conspicuous in the street scene. The dwelling’s main roof form has a gable at one end and a hip at the other, which contributes to its individualistic style. Insofar as it is visible from the road, it largely blends in with the mixed appearances of the buildings on either side of the [site address] . These are mostly 2 storey residential buildings of different styles and varied roof forms, and large commercial buildings that are situated within an area that, whilst verdant, lacks discernible cohesion and consistency in built forms. The evidence suggests that the bungalow near to the [name] has approval1 for an additional storey.

Although the proposal would inevitably change the appearance of the appeal dwelling, it would largely reflect its existing roof form, albeit at a higher level. Whilst the proposed upper floor would be stepped, with a wider proportion set partly under a shallower roof slope, the differences between the roof slopes and the alignment of the surfaces of the front elevation, whilst noticeable, would not be so pronounced as to be awkwardly discordant or incongruous, and the eaves level would be consistent. Together, they would be well-proportioned and would serve to break up the massing of the front elevation. The matching materials and the broadly consistent pattern, proportions and alignment of window openings would unify the existing and proposed elements of the appeal dwelling.

Despite changing its appearance, the proposal would reflect the individuality of the host dwelling’s design and architectural features, ensuring sufficient unity between the existing and proposed elements. Set within its generous plot and behind some sizeable trees and well away from the nearest dwelling, I find that the scale, massing and external appearance of the appeal dwelling in its proposed extended form would be satisfactorily absorbed within its verdant surroundings, including the buildings of mixed appearances and sizes.

For these reasons, I conclude that the proposal would not have a harmful effect on the external appearance of the host building or its surroundings, and therefore prior approval should be granted under Article 3(1) and Schedule 2, Part 1, Class AA of the GPDO.

The matters set out within [name].2.(3)(a) of Class AA do not include the effect of the development on a Green Belt, including any impact on openness. Therefore, even if the site is within the Green Belt, it has no bearing on my considerations in this appeal.

Development allowed under GPDO Class AA is subject to a number of conditions listed under [name].2.(2) and (3) of Class AA. I find no justification on the evidence before me to impose any additional conditions as part of my decision.

For the reasons given above, I conclude that the appeal should be allowed and prior approval granted.