Single storey rear extension

Appeal Decision Site visit made on 13 July 2026 by R Standfield BSc (Hons) MA MRTPI an Inspector appointed by the Secretary of State Decision date: 28 September 2026 Appeal Ref: 6009359 76 Mallard Way, Aldermaston, Reading, West Berkshire RG7 4US • 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 T Cross against the decision of West Berkshire Council. • The application Ref is 25/02769/HOUSE. • The development proposed is single storey rear extension. Decision 1. The appeal is dismissed. Preliminary Matter 2. The National Planning Policy Framework (the NPPF) was updated on 17 August 2026. Both of the main parties to this appeal have had the opportunity to comment in light of the revised document and such comments as were submitted have been taken into account accordingly. Main Issues 3. The main issues are: • whether there would be an increased risk of flooding from surface water; and • the effect upon trees nearby the site. Reasons Surface Water Flood Risk 4. The site falls within Environment Agency (EA) flood zone 2. The Council further identifies the area as having a high surface water flood risk due to the water table being very close to ground level. The residential use of the site qualifies the proposed development as ‘more vulnerable’ to flood risk. The submitted Flood Risk Assessment (FRA) sets out measures to ensure that the extended dwelling would be safe from flooding. 5. The NPPF states that all development should be safe for its lifetime and should not increase flood risk elsewhere. Together with the NPPF, Policies SP5 and SP6 of the West Berkshire Local Plan Review 2023-2041 (the Local Plan) seek to manage and reduce flood risk from all sources. This includes the implementation of sustainable drainage systems. 6. Whilst there would be limited additional surface water generated over and above that arising from the current hardstanding, the introduction of a dual-pitched roof Appeal Decision 6009359 2 and the fall introduced to the replacement patio would collect and concentrate surface water drainage into channels. 7. The purpose of the FRA is to provide proportionate evidence that the level of flood risk would be acceptable. Whilst the EA has raised no objection to the proposed development, I am not provided with any assessment of drainage capacity at the site. There is also no evidence that either the proposed French drain or the soakaway would provide a workable drainage solution in this location. 8. The Council’s Sustainable Drainage Systems Supplementary Planning Document (SPD) (2018) confirms that high groundwater levels may prevent the use of some types of drainage that rely on infiltration. It advises that the base of an infiltration unit must be at least 1 metre above the highest expected groundwater level. This suggests that the drainage strategy as proposed may not be suitable for this site. Whilst a viable drainage strategy would represent betterment to the overall circumstances of the site, the information provided is not sufficient to make this conclusion. 9. The matter of a water table at or very close to ground level distinguishes this case from others where sustainable drainage may be secured by planning condition. Planning conditions are used in circumstances where concerns about a development can be addressed and made acceptable. Given the uncertainty regarding the ability to provide adequate sustainable drainage measures by the means proposed, the matter is not suitable to be addressed via planning condition. 10. The appellants suggestion to attach a condition raising the finished floor level of the extension would not deal with the potential risk of surface water building up and flowing into neighbouring land. This could therefore potentially increase flood risk elsewhere. 11. I have been provided with details of a similar extension permitted at a nearby property on Mallard Way. In that case, the FRA provided assurance that the construction of the extension via a block and beam floor would provide some capacity for floodwater under the building. The proposal was also considered in light of the fallback position for a larger extension. As such, there are key differences in the circumstances before me, and I therefore afford the example limited weight. 12. My attention has also been drawn to the fact that the appeal property remains in its original form in a locality where residential extensions are common. It may also have the potential for development under permitted development rights. However, I do not have a specific proposal before me that could be constructed under those rights to allow comparison of its impact. As such, I give this possibility limited weight in my decision. 13. For the above reasons, the information provided does not show that the proposed development complies with Policies SP5 and SP6 of the Local Plan, which require the use of sustainable urban drainage systems to adequately manage flood risk. Trees 14. The appeal site is a two-storey end-of-terrace dwelling positioned adjacent to the Kennet and Avon Canal at the end of the Mallard Way / Heron Way housing development. A triangle of land to the rear is bounded by the canal corridor and Appeal Decision 6009359 3 rail line, with no formal public access. The land is heavily vegetated, including mature trees. Whilst not protected by way of Conservation Area designation or Tree Protection Orders, the trees are valued for their contribution to the natural environment. They make a positive visual contribution to the area, particularly to the canal corridor with its public right of way. 15. The construction of the proposed soakaway, potentially within the root protection zones of trees, would risk damage to their root systems. In this instance, the potential impact could be addressed by the imposition of planning conditions. These could ensure that the siting of any drainage measures is outside the root protection zones, and that appropriate tree protection measures are agreed and employed. As such, the proposed development could comply with Policies DM15 and DM28 of the Local Plan which require the protection and management of trees. Other Matters 16. The site is in proximity to the North Wessex Downs National Landscape where I have a duty to seek to further the purpose of conserving and enhancing its natural beauty. The proposed development is very small in scale, sits among existing dwellings, and far enough from the National Landscape boundary that it would not harm the landscape, which would be conserved. I am therefore satisfied that my statutory duty is discharged. 17. The site is positioned within an Impact Risk Zone for the nearby Site of Special Scientific Interest (SSSI) and within a red impact zone for Great Crested Newts. As I am dismissing the appeal for other reasons, I have not considered this further. 18. There is reference to the absence of constructive engagement between the Council and the agent or appellant before the planning application was decided. However, this is not an issue that I can address as part of this planning appeal. Planning Balance 19. NPPF Policy S3 applies a presumption in favour of development with Policy S4 providing that development proposals within settlements should be approved unless the benefits of doing so would be substantially outweighed by any adverse effects when assessed against the national decision-making policies of the NPPF. 20. NPPF Policy L2 promotes the effective use of land by way of creating floorspace within an existing plot however the current absence of evidence regarding safe access and egress in relation to flood risk prevents substantial weight being afforded in this respect. The benefit of improved living accommodation for the occupants of the dwelling is afforded limited weight in favour of the proposal. The overall improvement of the surface water drainage arrangements could be a benefit subject to an acceptable scheme however at present, this is not evidenced. 21. The proposed development would conflict with other policies of the NPPF, including Policies CC3 and DP3.2b in relation to climate change adaptation, and Policies F7 and F8 which specifically relate to the risk of flooding both to the site and elsewhere. Policy F8.1 states that development proposals should not present a risk from flooding to potential occupiers, users, or visitors, and should not increase flood risk elsewhere. The proposal has failed to show that this could be achieved. Appeal Decision 6009359 4 22. In addition, the proposed development would conflict with the broad objectives of Policy N2 in relation to the natural environment albeit that this could be addressed by planning conditions. 23. In combination, I afford the adverse effects substantial weight. 24. As such, the adverse effects, when assessed against the national decision-making policies of the NPPF, would substantially outweigh the benefits of the proposed development and would therefore fail to comply with the forms of development that could be approved under Policy S4. Therefore, the presumption in favour of development in Policy S3 is not engaged. Conclusion 25. Due to the identified risk of flooding, the proposal conflicts with the development plan as a whole. There are no material considerations, including the NPPF, that indicate that the appeal should be decided other than in accordance with it. As such, the appeal is dismissed. R Standfield INSPECTOR