Appeal 3348206

The appeal is dismissed. Appeal B Ref: APP/C1950/D/24/3350519

The appeal is dismissed.

In the period since the appeal was submitted the Government has published a revised version of the National Planning Policy Framework (the Framework) in December 2024 which takes immediate effect. None of the changes are of significance for this appeal but I have used the paragraph referencing from the new Framework in my decision below.

The main issue is the effect of the proposed development on the character and appearance of the host dwelling, the surroundings of [address] and [address] and the wider [site address] Conservation Area. Appeal Decisions APP/C1950/D/24/3348206, APP/C1950/D/24/3350519

The appeal site is located on the west side of [address] close to the centre of Welwyn and within the [site address] Conservation Area. There is a mixed usage in this area but this mainly residential part of the Conservation Area is characterised by houses in spacious plots, harmonious house designs, uniform use of materials and a green streetscape of trees and hedged boundaries. From the appeal submissions it is clear that houses in this part of Welwyn are some of the original houses built in the garden city.

No 16 and No [address] were built as a symmetrical pair of 2 storey detached houses flanking the entrance to [address], a short cul-de-sac of semi-detached houses to the west.

No 16, as with other surrounding properties, is constructed in brick and tile with brick detailing. It stands in a large plot with the principal garden to the south of the house. No 16 is not listed but is identified in the Conservation Area Appraisal as a house of local interest in part because of its historical associations with [name], one of the Garden City pioneers, who lived in the house for a period.

In respect of the rear extensions and replacement garage, it is not a matter of dispute between the parties that the proposal would be acceptable and indeed planning permission was granted for these elements in July 2024. Ref 6/2024/0957/HOUSE. The issue is with the proposed side extension in both Appeal A and Appeal B. The only significant difference between the proposals is that the width of the side extension has been reduced in Appeal B to 2.9 metres from 3.9 metres in Appeal A (excluding the proposed bay window projection).

I have been referred to other properties in the area (particularly Nos 14 and [address]) where substantial extensions to the side of the properties have been allowed and which the appellant considers justify the appeal proposal. In particular, it has been put to me that the extension to No 14 has destroyed any symmetry that existed between Nos 14 and 16. However, I am not persuaded that this is the case, particularly in views northwards along [address] and looking at the two properties. Because the side extension to No 14 is set back from the frontage the frontage symmetry of the pair in this northwards view remains an important attribute which would be destroyed if the proposed side extension to No 16 were to be built. I acknowledge that in respect of the extensions to Nos 14 and 18 the Council must have, at the time, taken the view that the development would at least preserve the Conservation Area but these permissions do not necessarily justify the appeal proposal on this locally important building. I will therefore determine the appeal proposal on its own merits.

The Council has prepared Supplementary Design Guidance (SDG) which gives advice in respect of householder extensions amongst other things. The guidance requires extensions to be designed to complement and reflect the design and character of the dwelling and be subordinate in scale.

I acknowledge that in the various design iterations of the side extension the addition has been revised to be set back from the frontage and, particularly in Appeal B, would have a reduced width which the appellant considers would mean the extension would be subordinate to the house. However, the fact that the side extension and rear flat roof extension would wrap around the house to meet the two Appeal Decisions APP/C1950/D/24/3348206, APP/C1950/D/24/3350519 storey rear extension means that these elements would be read together and taken together would be greater than the depth of the original house. From the south in inward views from [address] this would appear as a disproportionate addition which would sit awkwardly with the attractive hipped roof and cubed form of the original house.

It has been put to me that adding the bay window to the side extension would reflect the current fenestration on the side elevation, that the parapet detail would soften the flat roof form and that the set-back would ensure the original frontage of the house was not affected. However, none of these details would sufficiently mitigate the adverse visual impact of the flat roof side elevation itself on the form and character of the original house.

I accept that, of the two proposals, the side extension proposed in Appeal B is better but it would still be harmful to the character and appearance of the original house. The height of the side extension rising to the mid-point between the current bay window and the first floor window and its flat roof form would be clearly visible from [address] over the current hedgeline in which view it would appear an obtrusive and alien addition. I acknowledge that the proposal would maintain the open aspect of the main garden and the appellants are in the process of landscaping the garden, which they consider would help reduce the visual impact of the side extension from the public domain. However, just because a development would eventually be partially screened from the public domain would not warrant allowing a design which would adversely impact on the character and appearance of the original house and would be detrimental to the character of the Conservation Area.

In terms of the rear extensions although concern has been raised regarding the demolition of the pitched roof outbuilding and its replacement with a flat roofed single storey extension this and the replacement garage would be tucked behind the dwelling off [address] and therefore contained by the form of the main house. In any event these elements have already been permitted under application ref. 6/2024/0957/HOUSE. Similarly, the two storey rear extension would form a well-designed subordinate addition to the original house, symmetrically placed on the rear elevation and reflecting the hipped form of the roof to the original. In all respects it would be in keeping with the character and appearance of the original dwelling and again has already been granted permission.

Section 72(1) of the Listed Buildings and Conservation Areas Act 1990 requires that special attention shall be paid to the desirability of preserving or enhancing the character or appearance of the area. For the reasons above, the erection of the side, flat-roofed extension would be harmful to the character and appearance of this locally important dwelling in [address] and thereby harmful to the significance of this part of the Conservation Area and fail to preserve its established character. As such the proposal would be contrary to Paragraph 212 of the Framework. For the same reasons it would also be in conflict with Policy SP15 of the Welwyn and Hatfield Borough Council Local Plan (WHBCLP) which seeks to conserve and, where appropriate, enhance the significance of the Borough’s heritage assets including the Conservation Area. Moreover, Policy SADM15 states that proposals should respect the character, appearance and setting of the asset and historic environment in terms of design, scale, materials and impact on key views. Similarly, Policy SP9 of the WHBCLP at the section on Building Function Appeal Decisions APP/C1950/D/24/3348206, APP/C1950/D/24/3350519 and Form requires alterations to buildings to relate well to the character and proportions of the existing building and its curtilage, the surrounding context and the street scene in terms of siting, height, mass, scale, design and materials. [name] acknowledge that the materials proposed would be appropriate, the siting, design and cumulative scale of the changes and their impact on views of the property conflict with these policy objectives.

I accept that the harm to the significance of the Conservation Area would be less than substantial and, in these circumstances, Paragraph 215 of the Framework states that the harm can be weighed against any public benefit. The appellant, in making the proposal, does not accept there would be harm to the Conservation Area and therefore has not presented evidence to demonstrate public benefits. The extensions proposed would constitute entirely private benefits for present and future occupants of the property and would not outweigh the identified harm to the significance of the Conservation Area from the proposal.

I understand the appellant’s wish to enlarge and improve the accommodation in the property to create a future proof, multi-generational family home thereby making sustainable and effective use of housing land, an objective which is encouraged by the Framework. However, although the Framework encourages the efficient use of land at section 11 it states in paragraph 129 that development should take into account the desirability of maintaining an area’s prevailing character and setting. The appellants already have permission for not insubstantial additions to the rear of the property but the additional proposal in respect of the side extension and its impact on character and appearance would fail the paragraph 129 test. Sustainable and effective use of the dwelling would not therefore outweigh the harm to the character and appearance of the original dwelling and the Conservation Area.

I have considered the matters before me in respect of both Appeals and, for the reasons given above, I conclude that Appeal A and Appeal B should both be dismissed due to the adverse visual impact that the side extension would have on the character and appearance of the host dwelling and the [site address] Conservation Area.