Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Site visit made on 12 May 2025 by S Burch BSc MSc MRTPI an Inspector appointed by the Secretary of State Decision date: 12th June 2025 Appeal Ref: APP/F5540/W/25/3360390 Land adjacent to 4 St Mary's Crescent, London TW7 4NA • 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 Nick Baxter against the decision of the Council of the London Borough of Hounslow. • The application Ref is P/2024/1514. • The development proposed is described as ‘Demolition of existing derelict garage and erection of two storey (including lower ground floor) one-bedroom dwelling (Class C3).’ Decision 1. The appeal is dismissed. Preliminary Matters 2. A revised version of the National Planning Policy Framework (the Framework) was published on 12 December 2024. The appellant and the Council have had the opportunity to comment on any implications for this appeal through their submissions. I have taken any comments made into account in my reasoning. 3. The appeal has been accompanied by an amended energy statement, in response to refusal reason 2 as listed on the Decision Notice.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision The fabric specifications proposed have been improved and the lack of PV panels has been justified by overshadowing from neighbouring properties. The statement demonstrates that the proposed development would achieve a 65% betterment over the notional dwelling. 4. Given the nature of the changes to the statement, I do not consider that it would introduce a fundamental change to the application, nor would it cause procedural unfairness to anyone involved in the appeal. I am therefore content that the amended statement is accepted and considered under this appeal. 5. The Council have viewed the amended statement and responded to it as part of their statement of case. They have confirmed that it overcomes the second reason for refusal and a carbon offset payment of £779 would be required to overcome any shortfall to net zero, however this could be secured via a condition if the appeal were allowed. On this basis, I am satisfied that, subject to the carbon offset payment which could be controlled by condition, the scheme would maximise the opportunities for carbon reduction on site at each stage of the energy hierarchy, in accordance with policy. Main Issue 6.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision The main issue is the effect of the proposed development on the living conditions of future occupiers, with particular regard to adequate internal and external space. https://www.gov.uk/planning-inspectorate

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision The main issue is the effect of the proposed development on the living conditions of future occupiers, with particular regard to adequate internal and external space. https://www.gov.uk/planning-inspectorate

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3360390 Reasons Living conditions- internal space 7. The appeal site is located between 153 Thornbury Road and 4 St. Mary’s Crescent. The site is occupied by an existing single storey detached garage with a pitched roof. The garage appears to be derelict. The site is located within the Osterley Park Conservation Area. 8. The proposed development would involve the demolition of the existing garage and the erection of a two storey, one-bedroom detached dwelling with a lower ground floor. 9. With regards to the internal space, the dwelling would have a gross internal floor area of 53 square metres (sqm) spread over two storeys. As outlined by Policy SC5 of the London Borough of Hounslow Local Plan 2015-2030 (LP) and Policy D6 of the London Plan, development proposals are expected to comply with the Nationally Described Space Standards (NDSS). 10. The submitted plans show a single bedspace, however the bedroom measures over 11.5 sqm. In order to provide two bedspaces, a double (or twin) bedroom should have a floor area of at least 11.5sqm. Therefore, a bedroom exceeding 11.5sqm is counted as a double (or twin) bedroom for two people.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision The minimum gross internal floor area for a one bedroom, two-person, two storey dwelling is 58sqm. The proposed dwelling falls short of this standard and by virtue of this, would result in cramped and substandard living conditions for future occupiers. 11. The case officer report also raises concerns regarding the provision of outlook and sunlight/daylight from the bedroom at lower ground floor level. It would be served by glass double doors which would open out into the subterranean courtyard area. The doors would face onto a retaining wall at a relatively short distance and there would also be walls to either side of the courtyard area. A footpath structure to allow access to the dwelling would sit above the courtyard and a fence would separate the dwelling from the highway at ground floor level. 12. Given the nature of the outlook, onto a subterranean courtyard and retaining wall, it is considered inadequate. The only outlook from this room would effectively be underground. The poor standard of outlook would be exacerbated by the presence of a footpath above to provide access to the dwelling and the proposed fence to the front of the dwelling.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision The resultant situation would also create a sense of enclosure from the bedroom which would be detrimental to the living conditions of future occupiers. 13. The appellant states the bedroom would mainly be used for sleeping during times of the day when curtains are likely to be closed. However, a bedroom is still considered a habitable room and should benefit from adequate levels of outlook. Furthermore, the appellant cannot be sure how future occupiers may choose to use the bedroom, which I note takes up most of the lower ground floor. The fact that the living room is dual aspect with outlook to the front and rear does not justify the poor standard of outlook from the bedroom. I am not satisfied that planting would sufficiently improve the outlook from the bedroom. 14. Turning to the provision of daylight and sunlight from the bedroom, limited evidence to demonstrate that the room would be afforded appropriate levels of https://www.gov.uk/planning-inspectorate 2

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3360390 daylight or sunlight has been submitted. Whilst a daylight and sunlight assessment has not been carried out, the appellant outlines that it is their professional opinion that the bedroom window would comply with ‘the Spatial Daylight Autonomy (sDA) test supported by BRE Site layout planning for daylight and sunlight (2022).’ However, due to a lack of further evidence to confirm this, I am not satisfied that this would be the case. Given the bedrooms location at lower ground floor level, coupled with the presence of an overhead footpath and fence to the front of the dwelling, it is my view that this room would not be afforded acceptable levels of daylight and sunlight. 15. Again, the appellant outlines how the bedroom would be used mainly for sleeping and activities that do not require a high level of natural light. They explain how the living room would benefit from good levels of daylight and sunlight, however this does not justify the inadequate provision of daylight and sunlight in the bedroom. The appellant can also not be sure how future occupiers may choose to use the bedroom. 16.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision I am not satisfied that the use of a permeable material such as metal grating or glass on the footpath structure would overcome the harm that I have identified above regarding both outlook and daylight/sunlight. Given the nature of the subterranean garden area, I do not consider it to be directly comparable to a recessed balcony. I am also not satisfied that a condition to restrict occupancy to one person would overcome the harm that I have identified above. In any instance, such a condition is unlikely to be enforceable. External space 17. Policy SC5 of the LP does not provide amenity space standards for a dwelling with only two habitable rooms. Therefore, in this instance, I find it appropriate to apply the standards as set out in Policy D6 of the London Plan. This policy requires a minimum of 5 sqm of private outdoor space for 1-2 person dwellings. 18. The submitted plans note that 19sqm of outdoor space would be provided. The 19sqm of amenity space includes the paved area to the front of the house, where the bin and cycle store would be located. Given this, the actual amount of useable amenity space is likely to be less than 19sqm.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Nonetheless, even with part of the space being used as a bin and cycle store, it would still exceed the 5sqm as required by the London Plan. 19. A proportion of the amenity space would be at subterranean level. As outlined earlier, this area would not benefit from adequate levels of natural light, and it would be somewhat enclosed by the presence of retaining walls and the footpath and fence above. This would affect future occupier’s enjoyment of their external amenity space. 20. However, a sufficient proportion of amenity space would be at ground floor level, providing acceptable levels of natural light and an adequate amount of space, even with a portion of this area being used for bin and cycle storage. This space would allow for relaxation, as well as essential activities such as drying space and storage. The scheme would therefore provide an acceptable amount of useable amenity space, in accordance with the standards as set out in Policy D6 of the London Plan. https://www.gov.uk/planning-inspectorate 3

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3360390 21. The Council raise concerns regarding lack of privacy in the garden, due to its positioning to the front of the dwelling. However, a fence is proposed to the front of the garden, which would ensure adequate privacy. 22. For the reasons given above, I therefore conclude that whilst the proposed development would provide acceptable external amenity space, it would result in substandard living conditions for future occupiers, by way of inadequate internal amenity space. As a whole, the scheme therefore fails to accord with Policy SC5 of the LP and Policy D6 of the London Plan. Collectively, amongst other matters, these policies seek to ensure that development provides a high standard of amenity for future occupiers. Other Matters 23. The appeal site is within the Osterley Park Conservation Area (CA). The statutory duty set out in Section 72 of the Planning (Listed Buildings and Conservation Areas) Act 1990 requires special attention to be paid to the desirability of preserving or enhancing the character or appearance of a Conservation Area. 24. The area surrounding the site comprises of a mixture of detached and semi- detached dwellings.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision There is little cohesion in the appearance of the area surrounding the site. The dwelling would replace an existing garage, and the proposed front elevation would somewhat resemble a garage. As the proposal is similar in footprint, height and design to the existing structure, it is my view that the scheme would preserve the character and appearance of the CA. The Council similarly conclude that the scheme would preserve the character and appearance of the street scene and wider CA, in accordance with relevant policy. 25. The appellant suggests in their Design & Access Statement that through the use of materials, the scheme would enhance the character and appearance of the CA. I however do not agree that this would be the case. The proposed materials are similar to the existing materials and in any instance, the proposed development would be somewhat screened from the wider CA by the proposed boundary treatment. In any instance, even if the proposed materials did enhance the character and appearance of the CA, I am not satisfied that this would outweigh the harm that I have identified above. 26. The Council raise concerns regarding flood risk and the location of the bedroom on the lower ground floor.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Section 4.7 of the Residential Extension Guidelines, Supplementary Planning Document (SPD) outlines how basements should not be used as a main living area or as sleeping accommodation due to concerns over flood risk and emergency access. In the event of an emergency, if future occupiers were unable to access the ground floor, the only means of escape would be via the light well. A secondary means of escape has been proposed in the form of a ladder at the end of the courtyard. However, a ladder would be not an accessible means of escape for all future occupants. The proposal therefore does not accord with these guidelines. 27. The appellant outlines how a similar proposal was granted permission in 2018 and there has been no material changes to policy on living standards that should supplant this decision. They also outline how flood risk was not raised as an issue in this application. However, I have limited information regarding this proposal before me and in any instance this decision predates the adoption of the London Plan. The London Plan places emphasis on providing a high standard of https://www.gov.uk/planning-inspectorate 4

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3360390 accommodation. The fact that flood risk was not mentioned previously does not justify the scheme not providing an accessible means of escape for all occupants. I have therefore afforded this matter limited weight in favour of the appeal. 28. The appellant states that the bedroom’s location at lower ground would ensure privacy for future occupants. They also outline how given the adjacent dwelling and CA, there is no scope to increase the buildings floor area. However, neither of these considerations justify the harm that I have identified above. Furthermore, whilst I note that Policy SC5 of the LP outlines how a flexible approach to the NDSS can be taken to residential conversions to achieve heritage conservation objectives, the scheme is not for a residential conversion. I do not find it appropriate to take a flexible approach to the NDSS in this instance. 29. The scheme would have an acceptable impact on the character and appearance of the area and would preserve the character and appearance of the CA. It would not harm neighbouring amenity and would ensure fire safety. The site is in a flood zone one and there are no trees on site.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision These considerations are however considered to be neutral factors and do not weigh in favour of, nor against, the appeal. 30. The proposal would deliver a net gain of one additional dwelling, therefore contributing to housing targets and boosting the supply of homes. The scheme is in a sustainable location with good transport links and access to local facilities. It would not detrimentally impact traffic or parking provision and would provide parking for bicycles. It would make use of a redundant and unkempt site. There would be temporary and ongoing economic benefits from the development, and the appellant has indicated that the build duration would be relatively short, with ample space for building equipment to be stored on site. The scheme would also provide some additional planting and ensure energy efficiency through its design. The appellant has suggested that the proposed use would stop fly tipping at the site. Overall, whilst these are important benefits, given the modest scale of the development I attribute limited weight to them. Conclusion 31.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — Appeal Decision Notwithstanding my favourable findings regarding the external amenity space, the harm that would be caused in relation to the living conditions of future occupiers due to the inadequate internal amenity space is such that the proposed scheme would not comply with the development plan considered as a whole. Therefore, the appeal should be dismissed.

Land adjacent to 4 St Mary's Crescent, Isleworth, London, TW7 4NA — London Borough of Hounslow — S Burch INSPECTOR https://www.gov.uk/planning-inspectorate 5