Single storey rear extension - to include 1x skylight, 10 glazing panels & Bi-folding door first-floor rear extension with rear dormer & roof-light - high opaque glass screen - sliding door fenestration changes - existing roof light will be removed - The existing garage side window will be replaced with a single door. The living area window will be replaced with a double door

Appeal Decision Site visit made on 5 October 2020 by M Chalk BSc (Hons) MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 16 October 2020 Appeal Ref: APP/N1920/D/20/3257092 Scratchwood House, Barnet Lane, Elstree WD6 3QU • The appeal is made under section 78 of the Town and Country Planning Act 1990 against a refusal to grant planning permission. • The appeal is made by Rutvig Patel against the decision of Hertsmere Borough Council. • The application Ref 20/0540/HSE, dated 20 April 2020, was refused by notice dated 15 June 2020. • The development proposed is described as “The erection of a single storey rear extension - to include 1x skylight, 10 glazing panels & Bi-folding door first-floor rear extension with rear dormer & roof-light - high opaque glass screen - sliding door fenestration changes - existing roof light will be removed - The existing garage side window will be replaced with a single door. The living area window will be replaced with a double door.” Decision 1. The appeal is dismissed. Main Issues 2. The main issues are: • Whether the proposal would be inappropriate development in the Green Belt having regard to the revised National Planning Policy Framework and any relevant development plan policies; and, • Would the harm by reason of inappropriateness, and any other harm, be clearly outweighed by other considerations so as to amount to the very special circumstances required to justify the proposal. Reasons Whether inappropriate development 3. The appeal site is in the Green Belt. The National Planning Policy Framework (the Framework) states that the construction of new buildings should be regarded as inappropriate in the Green Belt and that inappropriate development is, by definition, harmful to the Green Belt and should not be approved except in very special circumstances. Paragraph 145 c) of the Framework recognises as an exception to this the extension or alteration of a building provided that it does not result in disproportionate additions over and above the size of the original building. Appeal Decision APP/N1920/D/20/3257092 2 4. Policies CS13 of the Hertsmere Core Strategy 2013 (the CS) and SADM26 of the Hertsmere Site Allocations and Development Management Policies Plan (the DMPD) state, amongst other things, that in the Green Belt an extension or alteration to a building must not individually or cumulatively be disproportionate to the original building. 5. The Council suggests that the development proposed would result in a cumulative increase of 84% of the original floorspace, while the appellant argues that it would be 45%. This is a significant difference, and limited evidence has been submitted by either party to clearly show the basis of their calculations, but neither the Framework nor the development plan define ‘disproportionate’ in terms of the percentage increase. While floor area and volume calculations may be referred to in assessing whether a development would result in disproportionate additions, it is ultimately a matter of planning judgment based on the size of the resulting building. 6. The Council’s planning records show that the house was enlarged with single- storey extensions following a 1985 permission. The Council has referred to other additions shown in Building Control records, but details of these have not been submitted. Based on this, I have therefore taken the original building to be that which existed before implementation of the 1985 permission. 7. The house has already been extended to both sides, and the height of an earlier side extension would be increased to two storeys. The proposed rear extension would be 6 metres deep from the rearmost part of the house, and as wide as the two-storey core of the house. These existing and proposed extensions would cumulatively result in a substantial enlargement that I consider would amount to disproportionate additions over and above the size of the original building. 8. The proposal would therefore be inappropriate development in the Green Belt. It would conflict with the requirements of Policies CS13 of the CS and SADM26 of the DMPD as well as the requirements of the Framework. Other Considerations 9. The appellant has identified considerations which they contend weigh in favour of the appeal proposal. The development would improve privacy to the neighbouring property, Fieldings, by reducing the size of the roof terrace near the shared boundary. It would provide benefits to the occupiers of the dwelling by providing a swimming pool for exercise. 10. There would be no other harm to neighbour amenity or harm to the character and appearance of the house or wider area. The absence of identified harm is a neutral consideration in the determination of this appeal. 11. The appellant contends that the development would not be harmful to the openness of the Green Belt. However, impact on openness is not the test for extensions to buildings in either the development plan policies or the Framework. 12. Under the house’s Permitted Development rights, a further outbuilding could possibly be erected to accommodate the swimming pool proposed in the rear extension. However, no details of how large this building could be have been submitted and, in any case, a separate outbuilding would not be an Appeal Decision APP/N1920/D/20/3257092 3 enlargement of the original house. This possibility therefore attracts limited weight in the determination of this appeal. 13. The house could also be extended to the rear under its Permitted Development rights. However, the house has a stepped rear elevation, the previous side extensions wrap around the original rear elevation to an extent and the site slopes away from the house with significant differences in ground levels. It is not therefore clear from the information provided whether any rear extension that could be constructed under Permitted Development would be similar in size to the appeal proposal. In the absence of a certificate of lawfulness or similar proof of the potential for the house to be extended to the rear, I can therefore only give this potential fallback limited weight. 14. The appeal property is part of a group of buildings on this section of Barnet Lane. The other houses in the group have been the subject of planning applications for extensions and replacement dwellings. Replacement dwellings are a materially different development then that which is before me and assessed against different criteria. I therefore do not consider that these permissions are of direct relevance to this appeal. 15. The permissions for extensions are, in many cases, of considerable age and would have been assessed against a different set of policies than is currently the case. I note that many of the decisions considered the effect on the openness of the Green Belt, which is not a consideration in this appeal as set out above. I can therefore only give these permissions limited weight in determining this appeal. 16. The 2013 permission granted at Bayshill House was granted under the policies of the CS and the 2012 Framework, and therefore under much the same policy situation as presently exists. It allowed extensions in excess of 130% of the original floor area. However, in this instance an extant permission for a garage extension and the removal by condition of Permitted Development rights for extensions and outbuildings were considered to amount to very special circumstances that overcame the harm from the disproportionate additions. These specific circumstances do not exist in this case, and national Planning Practice Guidance states that conditions restricting the future use of permitted development rights may not pass the test of reasonableness or necessity. 17. The Framework states that substantial weight must be given to any harm to the Green Belt. While there would be benefits arising from the appeal proposal, these would be limited in scale. They would not clearly outweigh the harm by inappropriateness that would result from the development proposed. Accordingly, very special circumstances do not exist in this instance. Conclusion 18. For the reasons set out above, the appeal fails. M Chalk INSPECTOR