Erection of detached outbuilding

Appeal Decision Site visit made on 24 June 2025 by R Gee BA (Hons) Dip TP PGCert UD MRTPI an Inspector appointed by the Secretary of State Decision date: 11 JULY 2025 Appeal Ref: APP/A1910/D/25/3361864 Little Paddock Frithsden Copse, Potten End, Berkhamsted, Hertfordshire HP4 2RG • The appeal is made under section 78 of the Town and Country Planning Act 1990 (as amended) against a refusal to grant planning permission. • The appeal is made by Mr and Mrs J Gray against the decision of Dacorum Borough Council. • The application Ref is 24/01961/FHA. • The development proposed is Erection of detached outbuilding. Decision 1. The appeal is dismissed. Main Issues 2. The main issues are: i) whether the development would constitute inappropriate development in the Green Belt having regard to the National Planning Policy Framework (the Framework) and relevant development plan policies; ii) the effect on the openness of the Green Belt; and iii) if it is inappropriate development, whether the harm by reason of inappropriateness, and any other harm, would be clearly outweighed by other considerations, so as to amount to the very special circumstances necessary to justify it. Reasons 3. The appeal site comprises a substantial two-storey detached property set within a spacious plot. The dwelling is set back from the highway behind a high hedge and a landscaped area. The appeal property is located within a cluster of linear development, comprising large, detached properties, in similarly substantial plots. At my site visit I observed there to be an eclectic mix of property types in the immediate locality. Whether inappropriate development 4. The Framework identifies that the fundamental aim of Green Belt policy is to prevent urban sprawl by keeping land permanently open. It goes on to state that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. The Framework further establishes that the construction of new buildings in the Green Belt should be regarded as inappropriate, subject to a number of exceptions as set out in Appeal Decision APP/A1910/D/25/3361864 2 paragraph 154 of the Framework. One such exception being the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original dwelling. Policy CS5 of the Dacorum Borough Core Strategy (2013) (CS) broadly conforms to the general thrust of national Green Belt policy, in particular with regards to the limited extension of existing buildings. 5. On account of its position and distance from the host property I concur with the parties that it is reasonable to regard the proposed building as an extension to the existing property. 6. What constitutes a disproportionate addition is not defined within the Framework, nor within the CS. An assessment of whether the proposed extension would be ‘disproportionate’ in the context of paragraph 154 c) is therefore a matter of planning judgement. The Council’s evidence refers to Saved Policy 22 of the Dacorum Borough Local Plan (2004). It is understood that this set out a percentage increase ‘ceiling’ of 30% for an extension to be regarded as ‘limited in size’. However, I have not been provided with a copy of that policy, nor did it appear in the decision notice. Accordingly, it has had no part in my decision. Whilst floorspace calculations can be used as a guide to determine whether a proposal would be a disproportionate addition, in my view, it is a matter of planning judgement and can include aspects such as floorspace, height and volume. 7. The Framework defines ‘original building’ as a building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally. The evidence indicates that there have been many alterations made to the building, including two-storey side and rear extensions, porch, single storey extensions and garages. 8. When taken cumulatively with previous additions, the proposal would increase the floorspace of the original dwelling by 97%. Based purely on these statistical measurements the proposed and existing extensions would cumulatively lead to a sizeable increase in the floorspace of the original dwelling that could not be regarded as limited. 9. Whilst on its own, the proposed extension may well be acceptable, when combined with the existing extensions, it would represent a significant increase in the volume, floorspace and scale, such that it would clearly be disproportionate to the original building. In controlling disproportionate additions, Green Belt policy seeks to avoid properties becoming ever larger through incremental extensions, and the associated increase in built form in the Green Belt. In this case, the property has already been extended significantly and consequently, the proposal fails to meet the exception under paragraph 154 c) of the Framework. 10. For the reasons stated, the proposal would result in inappropriate development in the Green Belt. Conflict therefore arises with Policy CS5 of the CS and the Framework Openness 11. The Framework defines one of the essential characteristics of the Green Belt to be its openness. There is no formal definition of openness but, in the context of the Green Belt, it is generally held to refer to an absence of development. Case law1 1 Turner v SSCLG & East Dorset Council [2016] Appeal Decision APP/A1910/D/25/3361864 3 has established that openness has both a spatial (physical) dimension, and a visual aspect. 12. The proposal would introduce built form where presently there is none. Therefore, the proposed development would spatially reduce openness. 13. The siting of the appeal proposal, set back from Frithsden Copse behind substantial hedges to the boundaries of the plot, and its limited height, means that the proposed addition would not be unduly prominent when viewed from the lane. Consequently, I find that the proposal would have a limited visual impact. 14. Taken together, the spatial and visual impacts of the proposal would result in some reduction in openness. However, having regard to the overall context of the appeal property, the proposal would only result in moderate harm to the openness of the Green Belt. Be that as it may, conflict would arise with the aims of including land within the Green Belt when assessed against the Framework, to which I attach substantial weight. Other considerations 15. The Framework states that inappropriate development should not be approved except in very special circumstances. These circumstances will not exist unless the development’s harm to the Green Belt by reason of inappropriateness and any other harm, is clearly outweighed by other considerations. 16. Two judgments2 have been brought to my attention which serve to illustrate that a combination of several ordinary factors can result in ‘very special circumstances’. They set out that in the context of proposals within the Green Belt, that relatively ordinary matters can be given significant weight depending on the circumstances of the case and confirming that matters which can constitute ‘very special circumstances’ are wide ranging. 17. I have had regard to the appellant’s representations in support of the appeal. It is stated that the outbuilding does not harm the rural character and appearance of the area and is compatible physically, functionally and visually with the garden. 18. The evidence indicates that the appeal site lies within the Chilterns National Landscape. The proposed design of the scheme has been considered having regard to these designations. It is considered that the proposal would only make minor changes in an already built-up area and would not harm the National Landscape. The Council has not raised any concerns in this respect and, even when giving great weight to conserving and enhancing landscape and scenic beauty, as set out in the Framework, I see no reason to disagree. 19. My attention has been drawn to a number of extensions to properties in the locality including Beauport, Meads, Tanglewood, High Beech, Longacres and The Grange, all of which are located along Frithsden Copse3. I have been provided with copies 2 Basildon District Council v First Secretary of State and Mrs R Temple [2004] EWHC 2759 (Admin); Brentwood Borough Council v SSE [1996] 72 P&CR 61 3 Appeal Decision APP/A1910/D/23/3326747: The Grange, Frithsden Copse, Potten End, Application 4/03182/15/FUL: Beauport, Frithsden Copse, Potten End, Application 21/04791/FHA: Beauport, Frithsden Copse, Potten End, Application 21/01605/FHA: Beauport, Frithsden Copse, Potten End, Application 4/03406/16/FHA: Beauport, Frithsden Copse, Potten End, Application 4/02009/19/FUL: Meads, Frithsden Copse, Potten End, Application 4/02249/12/FUL: Tanglewood, Frithsden Copse, Potten End Application 4/03125/15/FHA: High Beech, Frithsden Copse, Potten End, Application 4/00881/11/FHA: Longacres, Frithsden Copse, Potten End, Application 4/02634/05/FUL: The Grange, Frithsden Copse, Potten End, Application 21/01477/FHA: The Grange, Frithsden Copse, Potten End Appeal Decision APP/A1910/D/25/3361864 4 of plans, officer reports and decision notices. Whilst I recognise there may be similarities between proposals and the appeal scheme, each case has its own set of circumstances. In respect of the proposal allowed on appeal at The Grange the circumstances differ in that the site had been subject to a replacement dwelling. In any event, I am not bound by other decisions of the Council and have assessed this proposal on its own merits. 20. The proposed development would be within the confines of a residential plot and would not conflict with any of the purposes of the Green Belt. There is no dispute that the proposal would be in keeping with the architectural style of the host dwelling. However, the design attributes of the proposal and additional landscaping do not persuade me that the proposal would be acceptable having regard to the overall requirements of the development plan and the Framework relating to the assessment of proposals in the Green Belt. Similarly, the absence of harm to living conditions is a neutral matter. I recognise that there would be some economic benefits, albeit limited owing to the scale of the proposal, arising from its construction. I also recognise the benefits to the occupants of the property through enhanced living accommodation. Green Belt Balance and Conclusion 21. Having regard to the development plan and national planning policy, the proposal would result in disproportionate additions over and above the size of the original building and therefore comprises inappropriate development in the Green Belt. There would also be moderate harm arising from the proposal on the openness of the Green Belt. 22. The Framework says that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances, and that substantial weight is given to any harm to the Green Belt. 23. I find that the other considerations put forward by the appellant fall short of clearly outweighing the harm identified and thus the ‘very special circumstances’ necessary to justify the development do not exist. As such, the proposal would be contrary to the development plan and Framework when considered as a whole. The proposal would therefore not constitute a sustainable development. 24. The appeal is therefore dismissed. R Gee INSPECTOR