Proposed basement under existing building and rear patio – with light-well to front elevation

Appeal Decision Site visit made on 14 August 2023 by Andrew Dale BA (Hons) MA MRTPI an Inspector appointed by the Secretary of State Decision date: 6 September 2023 Appeal Ref. APP/N5090/D/23/3320473 40 Corringham Road, London NW11 7BU • 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 Mr Thomas Levinson against the decision of the Council of the London Borough of Barnet. • The application ref. 21/6722/HSE, dated 22 December 2021, was refused by notice dated 13 March 2023. • The development proposed is “Proposed basement under existing building and rear patio – with light-well to front elevation”. Decision 1. The appeal is allowed and planning permission is granted for proposed basement under existing building and rear patio – with light-well to front elevation at 40 Corringham Road, London NW11 7BU in accordance with the terms of the application ref. 21/6722/HSE, dated 22 December 2021, subject to the conditions contained in the Schedule at the end of this Appeal Decision. Preliminary matters 2. An application for a full award of costs has been made by Mr Thomas Levinson against the Council of the London Borough of Barnet. This application will be the subject of a separate decision. 3. The plan (drawing no. 2334-200.1) showing the proposed ground and basement floor layouts was updated during the processing of the application. I have taken revision D, dated 22 September 2022, into account as this shows the rear garden, rear paving and rear patio/raised terrace to remain as existing which would align with the additional comments made by the agent on drainage matters on 28 November 2022 in response to the Barnet/Capita comments of 17 August 2022. To be consistent, I have had regard to the other drawings of the same date, namely drawing nos 2334-201.1 Rev. B (Proposed Section AA) and 2334-202.1 Rev. B (Proposed Front & Rear Elevations). 4. The exceptionally fine oak tree behind the appeal property is not accurately recorded on drawing no. 2334-300. The oak tree is actually in another garden a little further away from where it is shown on that drawing. Still, the temporary tree protection fencing, in terms of its siting and specification details, shown on drawing no. 2334-300 remains appropriate. Appeal Decision APP/N5090/D/23/3320473 2 Main issue 5. Flowing from the sole reason for refusal, the main issue is the impact of the proposed single floor basement upon the character and appearance of the host dwelling and the wider locality. Reasons 6. Located on the south side of Corringham Road and paired with no. 42, the appeal property is a semi-detached house of 2 full storeys with further rooms in the roof space and a store room in a small basement under the rear raised terrace. Standing on a rectangular-shaped plot which slopes away from the house at the rear, its scale, design and architectural quality are fairly typical of the houses in the local residential area along this part of Corringham Road. 7. It is apparent from the site history and from what I saw on my visit that the appeal property has been previously enlarged with a part single, part 2-storey rear extension including a terrace with a balustrade and steps and with a sizeable rear dormer window to facilitate a loft conversion or second floor. 8. The Council said that the proposed development, by reason of its excessive size and scale, when considered cumulatively with existing extensions to the property, would represent an overdevelopment of the site which would be detrimental to the character and appearance of the property and wider locality. 9. The Council’s Supplementary Planning Document: Residential Design Guidance October 2016 (SPD) is referred to by the parties. I have had particular regard to paragraphs 14.42 to 14.45 which deal with basement extensions and to paragraphs 14.2 and 14.3 which refer to the cumulative effect of extensions. The SPD clearly carries weight as a material consideration in decision making but it contains recommendations as opposed to planning policy and should not be applied prescriptively to the exclusion of all other factors, including the physical circumstances and context of a site. 10. Whether any scheme would lead to an overdevelopment of a site would be a matter of fact and degree in each particular case. Given the wording of the reason for refusal, it seems to me that some external manifestation of a notable change in scale and size in relation to the site and its surroundings should be apparent to viewers. 11. The proposed basement, adding a further stated 134 sq. m of floor space onto the floor space of the earlier extensions, would result in the house being over 2.5 times larger than the original building. However, relying solely on increases to the gross internal area compared to the original or existing house would be unwise where basement extensions are being proposed. This is because the floor areas so created are substantially concealed beneath the existing house, as in the appeal case and the percentage increase in floor space arising from any proposal for a full basement is, by definition, always likely to be significant. 12. The SPD states that the Council will normally allow single floor basement extensions which do not project further than 3 m from the rear wall of the house or more than half its width beyond each side elevation and do not require the removal of more than 50% of the outdoor amenity space. The rear of the basement would project no further back than the current rear wall Appeal Decision APP/N5090/D/23/3320473 3 enclosing the store room in the small basement under the rear raised terrace which is an integral part of the existing overall built structure and an entirely logical place for the end of the proposed deeper basement. There would no lateral extension beyond the sides of the house and no obvious areas of exposed sunken garden next to the basement rooms. Only a nominal amount of amenity space would be taken up for the front light-well. Ample rear garden space, as existing, would remain available both in functional and visual terms. 13. The SPD says any exposed area of basement should be subordinate to the property and respect its original design and proportions. The basement’s front bay window would respect the design of the original 2-storey bay above. The single front light-well would be relatively small, sited well back from the road and secured by a grille which would sit flush with the natural ground level. The plans show planting around the light-well which would be desirable but not absolutely necessary given that it would be a sufficiently modest intervention in itself. The glazed panels at the rear of the basement would roughly align with, but not be as tall as, the folding lounge doors above. The scheme would also bring about the squaring up of the rear raised terrace and a straighter alignment to the steps at the side. Such minor changes to the rear elevation, which is not open to any clear public views, would respect the building’s established architectural character and its surroundings. 14. The appellant and the Planning Officer’s Report (POR) point to planning permissions for basement extensions at nos 42 and 46. These may be smaller than the basement proposed but it is a telling point that the POR explained how the resulting rear elevation would have a similar appearance to that of no. 42. Moreover, no. 42 has above-ground extensions on 3 levels at the rear that are almost identical to those at no. 40, except the ground and first floor extensions at that neighbouring property project further back than their counterparts at no. 40 by about 0.5 m. I did not identify any other light-wells along this road except at no. 2, which appears to be divided into flats, where there are 2 light- wells secured by railings which are quite noticeable in the street scene. The proposed light-well and grille at the front of no. 40 would be not nearly as visible by comparison. 15. The change in the property’s scale and size in relation to the site and its surroundings would be within tolerable limits and would not be readily apparent to viewers. The proposed basement would not amount to an oversized addition and would not by itself, or in combination with the earlier rear extensions, lead to the overdevelopment of the site. Rather, I consider that the proposed building works, viewed as a whole, would represent a visually acceptable solution, exhibit a high standard of design, be sufficiently complementary and sympathetic to the already extended parent building and be respectful of the established street scene along Corringham Road. The visual harmony of the group of buildings on this street would not be seriously disturbed. The scheme would also pay sufficient regard to the advice in the Council’s SPD. 16. I find on the main issue that the proposed development would preserve the character and appearance of the host dwelling and the wider locality. It would therefore comply with Policy D3 of the London Plan 2021, Policies CS1 and CS5 of Barnet’s Local Plan Core Strategy 2012 and Policy DM01 of Barnet’s Local Plan Development Management Policies 2012. Those policies, amongst other things, seek to ensure development respects local context and distinctive local Appeal Decision APP/N5090/D/23/3320473 4 character by creating places and buildings of high quality design and respects the appearance, scale, mass, height and pattern of surrounding buildings, spaces and streets. They are consistent with the National Planning Policy Framework insofar as it relates to achieving well-designed places. Other material considerations 17. The proposal provoked wide ranging responses from over 20 local residents who also commissioned a report from a firm of hydrogeologists and environmental consultants (H Fraser Consulting Limited) which reviewed the application. 18. I see no reason to depart from the how the POR (at section 5.4) considered these responses. I would add the following on the most relevant matters. 19. The protection of the oak tree, which is well over 20 m away from the construction zone, could be secured by a planning condition. 20. The plans show that the basement would be used for ancillary residential purposes as a gym, games room, stores and utility room. There is no proposal for a second dwelling or flats. The scheme will enhance the quality of life for the occupiers of no. 40 by providing additional ancillary accommodation and space in a family home. This is a further factor that weighs in favour of granting planning permission. 21. The safe development of the site ultimately rests with the appellant and any appointed building contractors who must have regard to the Party Wall Act and the Building Regulations. 22. The potential of the scheme to increase flood risk is clearly of great importance to local residents. Given the location of the site within the Golders Green Critical Drainage Area and upslope from residential properties in Middleton Road that are at high risk from surface water flooding, the Council was justified in seeking further information in line with the conclusion of the report by H Fraser Consulting Limited. The appellant commissioned and submitted a flood risk assessment and drainage strategy, a basement impact assessment and other supporting material. This information was scrutinized by the Council’s Surface Water Management Team who raised no objections on the grounds of surface water flooding and drainage and groundwater management. The Council acts as the Lead Local Flood Authority. I find no reason to dispute the Council’s finding on these matters. Conditions 23. I have considered the conditions suggested by the Council in the POR which the appellant will be familiar with. In addition to a condition setting a time limit for the commencement of work, a condition requiring that the development is carried out in accordance with the relevant approved drawings and documents is necessary as this provides certainty. A condition requiring the use of matching external materials is imposed to ensure that the development preserves the character and appearance of the building and the area. 24. I have included the suggested conditions relating to the implementation of a Demolition and Construction Management and Logistics Plan, privacy screens along the depth of the raised patio/terrace on the side facing no. 38 and the Appeal Decision APP/N5090/D/23/3320473 5 permitted hours for construction work, all in the interests of safeguarding the amenity and living conditions of nearby residents. Protection of existing trees, in accordance with drawing no. 2334-300, is also necessary in the interests of biodiversity and visual amenity. 25. To minimize the risk of flooding, I have also added the Council’s suggested condition covering the implementation of the mitigation and management proposals in the relevant technical reports. 26. It is not necessary to impose a condition which seeks to prevent the basement being occupied as a separate unit or dwelling because subdivision of the property into more than one dwelling would first require a separate planning application which would be determined by the Council in the first instance. Conclusion 27. For the reasons given above and having regard to all other matters raised, I conclude that this appeal should be allowed subject to the conditions below. Andrew Dale INSPECTOR Schedule of Planning Conditions 1) The development hereby permitted shall be carried out in accordance with the following approved plans and documents: 2334-500; 2334-501; 2334-100; 2334-101; 2334-102; 2334-103; 2334-200.1 Rev. D; 2334-201.1 Rev. B; 2334-202.1 Rev. B; 2334-300; Design and Access Statement + Heritage Statement dated 22.12.21; Delta MS500 Specifications; Delta-MS 20 Specifications; Delta Dual Sump V3 Installation Instructions and Technical Details; Delta Foul Retrofit Sump V3 Installation Instructions and Technical Details; Basement Impact Assessment REV 1 Nov 2022 by CGL REF CGE/16902 REV 1; Flood Risk Assessment and Sustainable Drainage Strategy REF 2355-FRA-DS-1-B REV B Issue Date 16 Nov 2022; PPS Specifications; and 2355-220801-PDG dated 1 Aug 2022 re existing and proposed drainage. 2) The development hereby permitted shall begin not later than 3 years from the date of this decision. 3) The materials to be used in the construction of the external surfaces of the development hereby permitted shall match those of the existing building. 4) No development or works shall take place on site until a Demolition and Construction Management and Logistics Plan (DCMLP) has been submitted to and approved in writing by the Local Planning Authority. The DCMLP submitted shall include, but not be limited to, the following: Appeal Decision APP/N5090/D/23/3320473 6 i. details of the routing of construction vehicles to and from the site, hours of access, access and egress arrangements within the site and security procedures; ii. site preparation and construction stages of the development; iii. details of provisions for recycling of materials and the provision on site of a storage/delivery area for all plant, site huts, site facilities and materials; iv. details showing how all vehicles associated with the construction works are to be properly washed and cleaned to prevent the passage to mud and dirt onto the adjoining highway; v. the methods to be used and the measures to be undertaken to control the emission of dust, noise and vibration arising from construction works; vi. a suitable and efficient means of suppressing dust, including the adequate containment of stored or accumulated material so as to prevent it becoming airborne at any time and giving rise to nuisance; vii. noise mitigation measures for all plant and processors; viii. details of the contractors compound and car parking arrangements; ix. details of interim car parking management arrangements for the duration of construction; and x. details of a community liaison contact for the duration of all works associated with the development. The development shall thereafter be implemented in accordance with the measures detailed within the DCMLP. 5) Before the basement hereby approved is first occupied, details of a privacy screen to be installed along the side of the raised terrace/patio facing 38 Corringham Road shall be submitted to and approved in writing by the Local Planning Authority. The privacy screen shall be fitted in accordance with the approved details before the basement is first occupied and retained as such thereafter. 6) No construction work resulting from the planning permission shall be carried out on the premises at any time on Sundays, Bank or Public Holidays, before 8.00 am or after 1.00 pm on Saturdays, or before 8.00 am or after 6.00 pm on other days. 7) No site works or development (including any temporary enabling works, site clearance and demolition) shall take place until the scheme of temporary tree protection fencing has been erected in accordance with the siting and fencing specification details shown on drawing 2334-300. This protection shall remain in position until after the development works are completed and no material or soil shall be stored within the fenced area at any time. 8) The development hereby approved shall be implemented in accordance with the mitigation and management proposals, including monitoring strategy, as detailed within the Basement Impact Assessment REV 1 Nov 2022 by CGL REF CGE/16902 REV 1 and the Flood Risk Assessment and Sustainable Drainage Strategy REF 2355-FRA-DS-1-B REV B Issue Date 16 Nov 2022. End of Schedule