21 Northumberland Crescent, FELTHAM, TW14 9SY

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Site visit made on 20 January 2026 by K Savage BA(Hons) MPlan MRTPI an Inspector appointed by the Secretary of State Decision date: 06 February 2026 Appeal Ref: APP/F5540/W/25/3375080 21 Northumberland Crescent, Feltham TW14 9SY • 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 Charles Fernandes against the decision of the Council of the London Borough of Hounslow. • The application reference is P/2025/0803. • The development proposed is the erection of a first floor rear extension and the conversion of the existing two storey side extension into a separate one-bedroom dwelling with parking. Decision 1. The appeal is dismissed. Preliminary Matter 2. I have used the description of development given on the Council’s decision notice as this more fully and clearly describes the proposal. Main Issues 3.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision The main issues are: i) The suitability of the existing dwelling for conversion; ii) Whether the proposal would provide a suitable standard of accommodation for prospective occupants; iii) The effect of the proposal on the character and appearance of the area; iv) The effect of the proposed rear extension on the living conditions of neighbouring occupants; v) The adequacy of proposed parking and cycle parking and the effects of these on highway and pedestrian safety; vi) The adequacy of proposed waste and recycling storage; vii) Whether the proposal would be acceptable in terms of addressing biodiversity net gain requirements. Reasons Conversion of Existing Dwelling 4. The appeal site is a semi-detached dwelling within an established residential street containing semi-detached pairs and short terraces of three to four dwellings. The streetscape is relatively consistent in form, dwellings being two storeys in height, primarily in red brick with pitched and hipped roofs. Front gardens are mainly given over to parking. https://www.gov.uk/planning-inspectorate

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3375080 5. Several dwellings, including the appeal property, have been extended to the side with two storey additions. A number of these side additions form separate residential units, including nearby at Nos 3, 6A, 12A, 16A and 19A. The proposal would follow a similar approach, essentially separating the extension from the original dwelling to form a new, standalone dwelling, to include a proposed rear addition at first floor level. 6. Policy SC6 of the Hounslow Local Plan (2015) (the HLP) seeks to manage the conversion and subdivision of buildings in a manner that contributes to housing supply without having an adverse impact on the character of an area or residents’ amenity. Among the criteria to achieve this are that dwellings have a minimum of 130sqm net original internal floor area to be considered suitable for subdivision. 7. The appellant argues that the policy is not relevant as the proposal would see No 21 return to its original size and layout, with the new dwelling wholly contained within the recent extension. It is indicated that the original dwelling was less than 60sqm in internal floor area, whilst the proposal would be some 49.5sqm.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Whether the ‘original’ floor area is considered as that preceding the extension or following it, it would fall well short of the 130sqm threshold. 8. However, I agree with the Council that it would be unreasonable to object to the main dwelling returning to its original size. Moreover, the evidence before me relating to similar development nearby suggests the threshold of Policy SC6 was not determinative in cases where the extension was proposed as a separate dwelling from the outset. Therefore, whilst there would be conflict with Policy SC6 in terms of the size of the dwelling to be converted, this is not a decisive factor in and of itself given the particular circumstances of the case. Standard of Accommodation 9. The proposal would create a one-bedroom unit within a narrow, deep floorplan across two storeys, including the proposed first floor rear extension. Nationally Described Space Standards and Policy D6 of the London Plan (March 2021) (the LP21) require a one-bedroom, two person dwelling over two storeys to have a Gross Internal Area (GIA) of at least 58sqm. At 49.5sqm, the proposed unit would fall short of this requirement by some 15%.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision I recognise that in certain scenarios, a modest shortfall can be overcome by an otherwise high quality layout. However, a 15% shortfall is significant against what are minimum standards. 10. Moreover, in this instance, the layout would fail to compensate for this shortfall. The floorplan would be deep and exceptionally narrow in width, served by small windows to the front and rear at ground floor. This would result in a confined, gloomy living space with limited functionality or room for comfortable circulation once necessary furniture is added. The first floor bedroom would accord with the minimum room size for a double room, but this would not render the living space satisfactory by itself. The outcome would be a cramped, poor quality environment that would significantly undermine the living conditions of prospective occupants. Nor would the provision of adequate external space within a divided rear garden be sufficient to address the inadequacy of the internal space, where occupants would spend the majority of their time. 11. I have had regard to the planning documents put to me for a number of the dwellings created in side additions nearby.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision However, comparing the plans, it is evident that in other cases, the dwellings created are demonstrably wider in their https://www.gov.uk/planning-inspectorate 2

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision However, comparing the plans, it is evident that in other cases, the dwellings created are demonstrably wider in their https://www.gov.uk/planning-inspectorate 2

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3375080 footprints, including No 5 at 3.5m wide and No 148 at up to 4.3m wide, compared to plans for the approved extension showing it at just 3m wide externally. These differences in width allowed these other schemes to achieve the necessary internal floorspace, and provide other features such as separate hallways. Thus, these schemes were able to provide more functional layouts compared to that before me. As such, I do not regard these developments as directly comparable to the appeal scheme, and they do not justify a proposal where the shortcomings in its internal layout are several and severe. 12. For these reasons, I conclude that the proposal would fail to provide a satisfactory standard of accommodation, and so would conflict with Policy D6 of the LP21 and the related aims of Policy SC5 of the HLP to provide development of the highest quality internally and externally. Character and Appearance 13. The Council’s concern is the proposed first floor rear extension, which would project some 3.6m in depth beyond the original first floor rear wall. Essentially, it would infill over the same footprint as the recent ground floor addition. 14.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision I saw on site that ground floor rear additions, such as that already in situ, are commonplace along this stretch of Northumberland Crescent, as are the two storey infills to the sides of semi-detached dwellings. However, I saw no other examples of rear additions at first floor level for some distance either side of the appeal site. The appellant has referred to examples at No 59 and beyond, as well as on Longford Avenue and Kingston Avenue but these are not observed within the same setting as the appeal site. Moreover, they would appear to amount to limited, sporadic examples that have not established first floor rear additions as a characteristic feature of the streetscape. 15. The proposal would introduce significant, high level massing to the rear of the property that would project conspicuously beyond a consistent, unaltered rear building line at first floor level. It would stand clear above garden boundary treatments and would form an incongruous extrusion visible from a large number of rear gardens. The cumulative massing of the side and rear extension would not be subservient in scale, but would physically and visually dominate the original dwelling, eroding legibility of its original scale and form. 16.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision For these reasons, the proposal would significantly harm the character and appearance of the area, contrary to Policies CC1 and CC2 of the HLP in terms of their expectations that developments achieve a high standard of design that respects the character of the area. Neighbours’ Living Conditions 17. The rear elevations of the dwellings are orientated southwards, and so benefit from good levels of sunlight and daylight. The proposed first floor extension, at 3.6m depth, would exceed the maximum projection of 2.5m set out in the Council’s design guidance1. The proposal would introduce a blank wall close to the shared boundary with No 19A that would be seen at close range from the rear first floor window. Given its proximity, height and depth, it would limit sunlight and increase shadowing to the neighbouring window in the afternoons. On the other side, the 1 Hounslow Character, Sustainability and Design Codes SPD – Part A5 Residential Extension Guidelines (May 2024) https://www.gov.uk/planning-inspectorate 3

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3375080 existing bedroom to No 21 would become a neighbouring window given the separation of the dwellings and would suffer a similar loss of sunlight in the mornings. 18. However, both windows would still retain good levels of sunlight and daylight for the majority of the day, and whilst the wall of the extension would be visible from the windows, there would remain a sufficiently broad, southerly vista over the rear gardens and beyond. Consequently, I find that the proposal would not cause significant loss of sunlight or outlook for neighbouring occupants, who would retain acceptable living conditions, and would not conflict with Policies CC1 and CC2 of the HLP which expects developments to have a positive impact on the amenity of current and future residents. Parking and Cycle Storage 19. The existing front garden of the site is hard paved, although a dropped kerb only extends in front of the extension, where previously stood a garage. Opposite the main dwelling are marked on-street parking bays, which were in use at the time of my visit. The proposal shows three off-street parking spaces to the front of the property spanning the width of the site.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision However, there is no detail before me as to how vehicles would access the site given the presence of on-street bays directly in front of two of the spaces, which are not proposed for removal. 20. As proposed, vehicles seeking to park in front of the retained main dwelling would have to cross over the footway at the dropped kerb and enter diagonally across the forecourt. The presence of other parked cars on the site, or in the parking bays, would make such a manoeuvre difficult, if not impossible. Reversing into or out of the spaces would also be hazardous given other parked cars would obscure sightlines. There would be a risk of damage to vehicles and harm to pedestrians should they be unsighted by a driver entering or leaving the site. 21. Moreover, the proposed layout does not include dedicated pedestrian routes between the parked cars to reach the front doors, which would at best inconvenience residents and visitors and at worst pose a hazard to their safe access and egress from the property. 22. Policy T5 of the LP21 requires that at least 1.5 secure cycle spaces should be provided for a one-bedroom, two-person dwelling.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision No details have been provided, but I concur with the Council that cycles could reasonably be stored securely in the rear garden and there is ample space for this. Details of this could be controlled by condition were permission to be forthcoming. 23. However, for the reasons set out, I find that safe and secure parking and pedestrian access would not be achieved. Moreover, the site circumstances, notably the parking bays on street, are fundamental constraints that mean potential solutions to parking are more than just minor questions of detail. Consequently, I am not satisfied that this is a matter which could be adequately resolved through a planning condition. 24. Therefore, I conclude that the proposal would cause harm to highway and pedestrian safety, in conflict with Policy T4 of the LP21 and Policy EC2 of the HLP, which require that proposals do not increase road danger and avoid adverse impacts on the transport network. It would also conflict with the Framework’s expectation that developments achieve safe and suitable access for all users. https://www.gov.uk/planning-inspectorate 4

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision Appeal Decision APP/F5540/W/25/3375080 Waste and Recycling Storage 25. The Council further points to the proposed forecourt parking leaving insufficient space for waste/recycling bin storage and cycle storage. The proposals would not provide any external route to the rear gardens, and therefore the strong likelihood is that bins would be stored to the front to avoid bringing waste through the dwellings. The plans show parking spaces taking up the majority of the forecourt, leaving limited margins where bins could be stored. I saw refuse collection locally uses a single wheeled bin and several smaller boxes, presumably for separated recycling. However, even if a location for these could be found within the forecourt, it would result in a cramped arrangement that would not be conducive to convenient use and management of the bins, creating a risk of unsightly waste build-up. Given there would be two properties, and thus two sets of bins, the adverse effect of this would be doubled. 26.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision The proposal would therefore conflict with Policy D6 of the LP21 and Policy EQ7 of the HLP, which require developments to provide adequate and easily accessible storage space that supports the separate collection of dry recyclables, food and residual waste. Biodiversity Net Gain 27. The provision of at least 10% Biodiversity Net Gain (BNG) is mandatory under Schedule 7A of the Town and Country Planning Act 1990. The appellant has claimed a self-build exemption on the application form, but the Council points to several documents not provided by the appellant to evidence their eligibility for self-build or custom housebuilding as defined by the Self-build and Custom Housebuilding Act 2015. There is also no legal agreement before me that would secure the proposed dwelling as a self-build unit. 28. The appellant argues that the absence of these documents does not equate to harm to biodiversity; that no trees, green cover or ecological features would be lost; and that opportunities exist for enhancements such as new planting and bird boxes.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision It is relevant that the only new built form would be the first floor extension, which would not result in any new ground coverage by buildings that would lower the existing biodiversity value. Given the depth of the rear garden, it is also likely that a sufficient net gain in biodiversity could be achieved, and could be detailed through the requirements of the standard condition. Therefore, even if a self-build exemption could not ultimately be demonstrated, I am satisfied that the proposal could accord with the mandatory BNG requirements of the Act. No conflict therefore arises with Policies G6 or G7 of the LP21 or Policy BG7 of the HLP. Other Matters 29. The Council did not identify harm in respect of other matters, including carbon emissions, sustainable construction, water use, drainage, contamination and fire safety. I have no reasons to depart from these conclusions, though an absence of harm means these are matters attracting neutral weight in the planning balance. Conclusion 30. On the main issues, the proposal would fail to provide an adequate standard of accommodation for prospective occupants or suitable means of waste storage.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision It would also fail to preserve the character and appearance of the area and would https://www.gov.uk/planning-inspectorate 5

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — Appeal Decision It would also fail to preserve the character and appearance of the area and would https://www.gov.uk/planning-inspectorate 5 Appeal Decision APP/F5540/W/25/3375080 create unacceptable risks to highway and pedestrian safety. This results in conflict with the development plan, taken as a whole, to which I afford significant weight. 31. The proposal would deliver an additional dwelling in line with the key aim of the Framework of boosting the supply of housing nationally, albeit the small scale of this contribution means it is a factor attracting limited weight in the scheme’s favour. There would be modest economic benefits from the construction of the dwelling and subsequent engagement by future residents in the local economy. 32. Overall, material considerations in this case, including the Framework, are not of sufficient weight to justify a decision other than in accordance with the development plan. Consequently, I conclude that the appeal should be dismissed.

21 Northumberland Crescent, FELTHAM, TW14 9SY — London Borough of Hounslow — K Savage INSPECTOR https://www.gov.uk/planning-inspectorate 6