Appeal 3320742

The appeal is dismissed.

The main issues in the appeal are the effect of • the proposed first floor rear extension on the character and appearance of the host dwelling, • the proposed first floor side-facing bedroom window on the living conditions of the occupants of [address] with respect to privacy, • the proposed first floor rear extension on the living conditions of the occupants and future occupants of the appeal site in respect of natural light and ventilation & • the proposal on the flood risk on the site and elsewhere.

The appeal site is a two-storey semi-detached dwelling with a long rear garden, located on the west side of [address]. Its semi-pair is no.39. No.43 is situated to its north and is built up to the common boundary with the appeal site. The site is within the [site address] Area of Special Local Character.

The appeal property has one rooflight in the front roof slope and one in the rear roof slope. There is a small bedroom in the roof space which is served by the front rooflight. There are three bedrooms on the first floor of the dwelling.

The proposed development would include demolition of a lightweight lean-to at the rear of the property and the provision of a full width rear extension with bi-fold doors out to the garden. It would be about 6m deep. At first floor level, there would be a rear extension of about 3m in depth in order to provide a new bedroom and ensuite bathroom.

The first floor extension would sit partially on top of the ground floor rear extension and would be the same width as the first floor width of the dwelling. It would have a hipped roof with a ridge at a lower level than the ridge of the main roof. A window would be inserted in the existing north (side) elevation which serves a bedroom. The width of the first floor extension would obscure all the first floor main rear elevation and part of the original main roof. This would bring about a significant detrimental change in character to the original dwelling and also result in an overly dominant extension at first floor/roof level in spite of the extension’s ridgeline being lower than the main roof.

In respect of the loss of character, policy DMHB 5 of the London Borough of Hillingdon Local Plan Part 2 - Development Management Policies (adopted 2020) “LP2” advises that, in Areas of Special Local Character, alterations should respect the established scale, building lines, height and design of the area and that extensions to dwellings should be subservient to and respect the architectural style of the original buildings. Whilst ground floor extensions tend to be less disruptive of original design, first floor extensions are often more difficult to integrate, especially on semi-detached dwellings. In this case, I find the first floor extension would not be sufficiently subservient and would not respect the architectural style of the original building. I have noted that roof pitches on extensions should be a similar pitch to that of the original roof (and in this case they would be similar) but roofs must also be subordinate to it in overall design. I find that the proposed roof including its pitch would not be subordinate in design or appropriately sympathetic in design to the original dwelling. I come to the same conclusion on the first floor rear extension as a whole.

Consequently, on the first issue, I conclude that the proposed first floor extension would harm the character and appearance of the host dwelling and in turn there would be some harm to the character of the Area of Special Local Character. It would conflict with policies BE1 and HE1 of the Hillingdon Local Plan Part 1 - [name] (adopted 2012) “LP1”, policies DMHB 5, DMHB 11 and DMHD 1 of LP2 and policy D3 of the London Plan 2021. Living conditions of Occupants of [address]

The first floor rear extension proposes introducing a side-facing bedroom window in the bedroom currently at the north-western corner of the dwelling. There is a first floor flank window at no.[address] serving a bedroom. These two windows would not be directly opposite one another and, in my view, there would be sufficient offset and distance between the windows to prevent intrusive mutual overlooking. Furthermore, both windows could be opened for ventilation without undue loss of privacy. 10.For these reasons, I conclude that there would not be an unacceptable impact on the living conditions of the occupants of no.[address] by reason of loss of privacy. There would not be conflict with those parts of policies DMHD 1 and DMHB 11 of LP2 which seek to protect the amenity of neighbours and householders. Living conditions of Occupants of [site address] 11.The Council raises concerns about substandard internal amenity for the occupants and future occupants of the appeal property and these focus on the availability or otherwise of natural light and ventilation to the side-facing first floor existing bedroom discussed above under main issue 2, to the existing loft bedroom and to the dining room and kitchen areas within the open plan ground floor (as proposed). Its concern is that these would cumulatively result in a substandard level of amenity for occupants of the dwelling if the proposed development took place. 12.In respect of the side-facing first floor bedroom window, whilst it would be north-facing it would be of a reasonable size and distance from any other potentially light-blocking built development such that it would allow sufficient natural light into the bedroom. It could have a fanlight/top opening section of window which would allow adequate ventilation. In respect of the rear rooflight, natural light would be partially blocked from it by the proposed first floor extension roof. However, it does not serve the loft bedroom as this is served by the front roof slope rooflight. I do not therefore consider that the living conditions in relation to natural light or ventilation would be unacceptable in the loft bedroom or the stairway up to it. 13.In respect of natural light and ventilation to the extended ground floor accommodation, whilst the open plan kitchen and dining area would be a deep space, the bifold doors would be extensive and would allow natural light and ventilation to penetrate the open plan space. On balance, there would be sufficient natural light and ventilation reaching that space. The Appellant indicates, and I agree, that even if a first floor rear extension was to obtain planning permission/be built, there could potentially be sufficient space in which to add a lantern or lanterns within the available flat roof space. 14.Consequently, on this issue, I conclude that the first floor rear extension would not result in unacceptable living conditions for the occupants and future occupants of the appeal site. There would be no breach of policy D6 of the London Plan 2021 or policy BE1 of LP1 in so far as they seek to protect residential amenity.

Policy advises that the appeal site falls within an area where a relevant development proposal will be required to submit an appropriate level Flood Risk Assessment to demonstrate that the development is resilient to all sources of flooding. 16.The submitted Flood Risk Assessment dated 24 January 2023 indicates that the surface water drainage strategy would employ a SUDS method. Amongst other things, a rainwater harvesting system using a tank would be employed. The details of estimated volume of existing surface water run-off and likely run-off volume post-development and proposed tank size are given and are reasonable. The proposed patio would use permeable paving slabs. The finished floor level would be set in line to the existing floor level which is higher than the recommended 300mm limit from the flood level. As a result, subject to attaching suitable planning conditions, I am satisfied that the submitted FRA demonstrates that there would be no undue flood risk to the appeal property or other property in the area from the proposed development. 17.Consequently, on this issue, I conclude that the proposed development would not result in undue flood risk within the site or elsewhere and would not be contrary to policy EM6 of LP1, policy DMEI 9 of LP2 or policy SI 12 of the London Plan 2021.