Appeal 3347324

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 Marsden Green and the wider [site address] Conservation Area.

The appeal site stands on the north side of Marsden Green within the [site address] Conservation Area. The street is lined by two storey housing with different styles to the north and south of the road. No [address] of linked, semi-detached houses with the two storey linking sections set well back from the frontage accommodating the garage for each property and accommodation above. The frontage is typical of the layout in Marsden Green and has a symmetrical and largely uniform appearance. The uniformity and spacious gaps at each end of the grouping contribute to the character of the Conservation Area at this point.

No 31, being at the western end of the group comprising Nos 31-49, does not have this two storey setback section but instead has a detached single storey garage and an open sky gap between No 31 and its neighbour to the west – No 29. The proposal would replace the garage with the two storey side extension connected to a single storey rear extension.

I have been referred to other properties in the area where side extensions have been allowed and which the appellant considers justify the appeal proposal. The property at No 51 and its side extension is most similar to No 31 and what is proposed. However, the extension in that case is set further back than that proposed at No 31 and unlike the proposal at No 31 it is not as wide as the main house. It is therefore materially different to that proposed at No 31. I accept that the principle of extending No 31 may be acceptable but it is the detail of the design that is important in terms of its impact and 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 the side extension would be set back from the frontage and set down from the ridge of the main house which the appellant considers would make the extension subordinate to the house. However, the side extension would not be set back as far as the side linking blocks in the rest of the neighbouring group. It would also be much wider than these linking sections and would be almost the same width as the main house. The side extension would therefore appear disproportionate to the main house.

The side extension as a result of this excessive width would also substantially fill the gap between the appeal property and No 29 with the side extension only one metre from the side boundary. It would be out of keeping with the uniformity of the neighbouring group and the rhythm of the indented side elements which are largely unaltered from their original design. I accept that in the approach from the east the existing house would partially screen the extension but from [address], diagonally opposite, and in the approach from the west along Marsden Green the side extension would appear overlarge closing down the spaciousness at the west end of the group.

In terms of the rear flat roof extension I do not dispute that the extension would not be out of keeping with similar rear extensions and would be acceptable. However, the rear extension is physically and functionally linked to the side extension and, combining the two extensions, the footprint of the house would be double the size of that which was originally constructed. The proposal would therefore cumulatively overwhelm the modest scale of the original house adversely affecting its character and appearance on the end of the uniform frontage to Nos 31-49.

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. The construction of this overly large and disproportionate side extension would be harmful to the character of Marsden Green and therefore harmful to the significance of this part of the Conservation Area failing to preserve the 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 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 and positioning on the plot, design and cumulative scale of the changes and their impact on views of the property and the neighbouring group 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, argues that the sustainable construction proposed for the extension would be a public benefit. However, this is an aspect that should now be delivered in all development and it would therefore be neutral in the balance. As the extensions are largely a private benefit for present and future occupants of the property they would have limited weight. Accordingly, I am not persuaded that there are public benefits to outweigh the harm to the significance of the Conservation Area from the proposal.

It has been put to me that the Framework states that “where the design of a development accords with clear expectations in plan policies design should not be used by the decision-maker as a valid reason to object to the development”. This quote is from a much earlier version of the Framework in 2019 pre-dating the strengthening of the Framework in respect of design matters. The relevant paragraph now is paragraph 139. Whilst the paragraph supports development that would reflect local design policies and help raise the standard of design in the area, for the reasons above, this is not the case here. Paragraph 139 commences by stating that development that is not well-designed should be refused.

I have had regard to the Public Sector Equality Duty contained in the Equality Act 2010 and understand the appellant’s wish to enlarge and improve accommodation in the property in order to allow the family to stay in the location and make sustainable and effective use of it as a family home, 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 proposal in respect of the side two storey extension and its impact on character and appearance would fail in this regard.

Accordingly, for the reasons above, the appeal proposal would have a detrimental impact on the character and appearance of both the house and the adjacent grouping as well as the surrounding Conservation Area and I conclude that the appeal should be dismissed.