Appeal 3319263

The appeal is allowed and planning permission is granted for a single storey ground floor rear extension, 3m depth at [site address] , Edmonton, Enfield [postcode] in accordance with the terms of the application Ref 22/03910/HOU, dated 17 November 2022, and subject to the following conditions:

The development hereby permitted shall begin not later than three years from the date of this decision.

The development hereby permitted shall be carried out in accordance with the following approved plans: SE/49FR/02; [postcode] /03; and SE/49FR/04.

The materials to be used in the external construction of the extension shall match those of the existing building.

The finished floor level to the extension shall match that of the existing dwelling.

No development shall take place above damp-proof course level until details of the water storage butt have been submitted to, and approved in writing, by the Local Planning Authority. Those details shall include: i) The location, size and external appearance of the water storage butt, ii) The manner of connection of the water storage butt to the rainwater downpipe, and iii) The method, manner and timing of discharge of the water storage butt. The water storage butt shall be installed prior to the first occupation of the extension and thereafter managed in accordance with the approved details.

The main issue is whether the proposed development would increase on and off-site flood risk and provide suitable flood control and mitigation.

The application proposes a single storey rear extension to an existing semi-detached dwelling. This would replace an area of paving which extends over the majority of the rear garden.

The appellant has provided a Flood Risk Assessment which concludes that flooding at the appeal property is unlikely to exceed 50mm. The finished floor level of the extension is nominated in the sectional plans to be 150mm above external ground level and this figure is not disputed by the Council. This is noted by the appellant as the same level as the remainder of the house. The extension would be constructed using impermeable materials below damp proof course to mitigate water ingress.

The extension is intended to provide ground floor washing facilities for a person with mobility issues. Non-level access to washing facilities, such as steps or a ramp, could negate the purpose of the extension. Furthermore, the finished floor level would be the same as at that of the remainder of the house. In the event that flood levels were to exceed the finished floor level, the remainder of the house would be inundated in any case.

The extension would replace an existing area of paving such that impermeable surfaces would not be increased overall. Therefore, downstream increases in flooding would be nil or negligible. However, the appellant also proposes a water storage butt from a rainwater downpipe. This would minimise peak flow discharge to the mains drains. It is reasonable and necessary to impose a condition to ensure the installation of this element of mitigation.

I conclude that the proposal would not result in a material increase in on or off-site flood risk and that mitigation measures are sufficient to reduce run-off in a peak flow event. The development therefore complies with policy CP28 of the Enfield Plan Core Strategy (2010) and policies DMD59, DMD 60, DMD 61 and DMD 62 of the Enfield Development Management Document (2014).

I have applied the standard time limit condition and a condition specifying the approved plans for certainty. In the interests of the character and appearance of the area, a condition is necessary to secure matching materials. Furthermore, I have imposed conditions to secure a water butt and finished floor levels to match the existing dwelling. Both parties have been provided with an opportunity to comment on the conditions and comments received have been taken into account.

The extension would not result in an increase in flood risk on or off site and provides sufficient mitigation. It complies with the provisions of the Development Plan, read as a whole. For the reasons set out above, the appeal is allowed.