Rear Extension, Loft Conversion & Internal Alterations. Demolition of existing detached garage and build of new garage structure to the side of the property

Appeal Decision Site visit made on 12 August 2026 by B Pattison BA (Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 26th August 2026 Appeal Ref: 6012008 Wilwyn, Chelmsford Road, Blackmore, Essex CM4 0SD • 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 Tom Boswell against the decision of Brentwood Borough Council. • The application Ref is 26/00225/HHA. • The development proposed is Rear Extension, Loft Conversion & Internal Alterations. Demolition of existing detached garage and build of new garage structure to the side of the property. Decision 1. The appeal is dismissed. Preliminary Matters 2. The National Planning Policy Framework (the Framework) was updated on 17 August 2026. Although I have made my determination against the updated national policy context, the relevant changes to the Framework are not fundamental to matters which are determinative to the outcome of this appeal. Main Issues 3. The main issues are: • whether or not the proposal would be inappropriate development within the Green Belt having regard to the Framework and any relevant development plan policies; • the effect of the proposal on the openness of the Green Belt; • the effect of the proposal on the living conditions of the occupiers of Brackens, with particular reference to outlook and light; • the effect of the proposal on the character and appearance of the host dwelling; and • if the proposal would be inappropriate development, whether or not 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 the proposal. Reasons Whether or not inappropriate development in the Green Belt Appeal Decision 6012008 2 4. The site is located within the Green Belt. Policy GB6.2. of the Framework states that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. 5. Policy GB7.1. of the Framework outlines categories of development which are not inappropriate in the Green Belt, and therefore should not be regarded as harmful to the Green Belt or be required to demonstrate very special circumstances. One exception is the reuse, extension, alteration or replacement of an existing building, provided that it is of permanent and substantial construction, is lawful in planning terms, and where any extension or alteration will not result in a disproportionate increase in size compared to the original building. The Framework explains that “original” in this case means the building as it existed on 1 July 1948 or, if constructed after 1 July 1948, as it was built originally. 6. Policy MG02 of the Brentwood Local Plan (2022) (LP) is broadly consistent with the Framework and outlines that development proposals within the Green Belt will be considered and assessed in accordance with the provisions of national planning policy. 7. The Framework does not specify either in relative or absolute terms what might be a disproportionate addition, nor have I been referred to any such figures in the Council’s development plan policies. The appellant does not dispute the Council’s calculation that the proposal, when combined with existing extensions to the dwelling, results in an increase in floor area of 239.4%. The rear extension would project 7.5 metres towards the rear of the appeal site. Taking these figures into account, the proposal results in a considerable increase in additional footprint and floor area. 8. I note that the ridge height would be similar to the adjoining property, Wellington and the increase to the building’s footprint would be to the rear. The surrounding area is marked by reasonably sized, often two storey dwellings positioned within amply sized plots. As a result, Wilwyn is currently notably smaller than other nearby properties. However, the Framework requires proposals to be assessed against the size of the original building. 9. I acknowledge that the proposal involves the demolition of the detached garage. However, in my view, due to the extent of new floorspace the proposal would disproportionately change the size of the original dwelling. This leads me to find that the proposal would results in disproportionate additions to the original building and thus fails to meet the exception within policy GB7.1. of the Framework. 10. Accordingly, I conclude that the proposal is inappropriate development in the Green Belt, having regard to the Framework. Inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Openness 11. Chapter 13 of the Framework identifies that the objective of Green Belt policy is to prevent urban sprawl by keeping land permanently open. The government attaches great importance to Green Belts, the essential feature of which are their openness and their permanence. Appeal Decision 6012008 3 12. The site comprises a detached dwelling sited within a residential plot, set back from the road. The site has a deep garden with a garage to the rear, and a driveway plus parking area to the front. Many of the properties along the road appear to have been extended in various ways, and unlike the appeal property many are two storeys in height. 13. The demolition of the garage would consolidate the built form of the building. However, there would be an overall increase in floor area at ground floor level. Whilst this would be to the rear it would result in the infill of space which was previously open. Furthermore, the increase in height would create an additional storey of accommodation at first floor level, resulting in a significant increase in floorspace. Overall, the proposed development would have an impact on both the spatial and visual openness of the Green Belt. 14. Given the context of the site within an area of larger residential properties, I consider the effects on both the spatial and visual openness of the Green Belt would be limited. Whilst limited, it would nevertheless erode the openness of the Green Belt, which, as noted, is one of its essential characteristics. 15. Therefore, I conclude that the proposal would not preserve, and would have a harmful effect on, the openness of the Green Belt. As such, it would conflict with the provisions within the Framework which seek to preserve the openness of the Green Belt. Living conditions 16. As the rear extension would be two storeys and constructed close to the shared boundary with Brackens its depth has the potential to impact the level of light for the occupiers of the neighbouring property. Brackens has rear facing first floor windows which serve a habitable room within a rear dormer. The presence of the rear extension of this depth, height and with limited separation from Brackens would cause overshadowing of the windows. 17. The Council refer to the Essex Design Guide (EDG). This discusses the obstruction of light to existing windows and outlines that harmful losses can be avoided by ensuring that an extension does not result in the centre of the existing neighbouring window falling within a combined plan-and-section 45 degree overshadowing zone. 18. The appellant has submitted annotated plan and elevation drawings which seek to demonstrate that the extension would not have a harmful effect on the occupiers of Brackens. In relation to the elevation, as the nearest part of the extension’s roof would pitch sharply away from the shared boundary, there would be no infringement to a 45 degree line drawn from the midpoint of Brackens first floor window. 19. In relation to the plan view, both parties agree that drawing W-0SD-26-PL006 indicates a breach of the 45-degree line, albeit a very minor one. Whilst the infringement is marginal, the proposed extension would nevertheless conflict with the guidance set out in the EDG, which advises that extensions should not breach the 45-degree line when measured from the nearest habitable room window. Taking this into account, and given the close proximity of the extension to the neighbouring property, I find that the proposal would result in a harmful reduction in the levels of daylight and sunlight reaching the affected accommodation. Appeal Decision 6012008 4 20. Views from Brackens' first floor rear window are primarily directed towards the rear of its garden. Although the extension would be visible in oblique views from the window, its position largely to the side of the window in question would reduce its visual prominence. As a result, the proposal would not be an especially dominant feature when viewed from the neighbouring property. 21. However, for the above reasons, I conclude that the proposal would harm the living conditions of the occupiers of Brackens, with particular reference to light. I therefore find that it would conflict with Policy BE14 of the LP. Amongst other aspects, this seeks to protect the living conditions of occupiers of neighbouring properties. It would also conflict with the aims of the Framework that seek proposals which provide healthy living conditions for occupiers and users in terms of adequate access to light. Character and appearance 22. The proposal would increase the ridge height of the dwelling, so that it would be comparable to that of Wellington, the neighbouring property to the left, when viewed from the street. The front elevation would incorporate a first floor gable and two smaller dormer windows facing the highway. Front facing gables are a notable characteristic of the nearby properties, Great Oaks and Cranbourne, which are situated immediately to the left of Wellington. In addition, dormer windows are a common feature on the front elevations of the majority of properties along this side of the highway. Consequently, the proposed design of the front elevation would be in keeping with both the host dwelling and the character of the surrounding street, and would not appear incongruous within its context. 23. Whilst of notable depth, the rear extension’s pitched roof form would minimise its bulk. When considered in the context of the neighbouring buildings, which are characterised by comparatively large footprints, the extension would fit into the existing built context without appearing visually dominant. In addition, as its form would be screened by the adjoining properties on either side of the appeal site, it would not appear as an especially prominent addition. 24. Therefore, the proposal would not harm the character and appearance of the host dwelling. There would be no conflict with Policy BE14 of the LP insofar as it requires proposals to meet high design standards. Other considerations 25. The proposal would deliver an improvement to the occupiers’ living conditions. However, the Framework is clear that substantial weight should be given to any harm to the Green Belt. As I have found that the proposal constitutes inappropriate development in the Green Belt, this reduces the weight I attach to this factor, and I therefore afford it only limited weight. Other Matters 26. The proposal would not harm the setting of nearby listed buildings. Nor would there be a harmful impact on highway safety. However, the absence of harm or conflict with other relevant development plan policies is a neutral factor and does not weigh in favour of the proposal. Green Belt Balance and Conclusion Appeal Decision 6012008 5 27. The proposal constitutes inappropriate development in the Green Belt which should not be approved except in very special circumstances. It does not preserve, and has a harmful effect on, the openness of the Green Belt. Therefore, the proposal is contrary to Policy MG02 of the LP and the principles of the Framework that seek to protect the Green Belt from inappropriate development. Substantial weight should be given to any harm to the Green Belt. In addition, I have also found harm to the living conditions of the occupiers of Brackens. 28. Very special circumstances will not exist unless the harm to the Green Belt, and any other harm, is clearly outweighed by other considerations. The other considerations in relation to the proposal do not clearly outweigh the harm that I have identified. Consequently, the very special circumstances necessary to justify the development do not exist. 29. The proposal is contrary to the development plan and the Framework taken as a whole. There are no other material considerations which indicate that the decision should be determined other than in accordance with the development plan. Therefore, for the reasons given above, I conclude that the appeal should be dismissed. B Pattison INSPECTOR