Local Requirements - Flood Risk Assessment (Householder)

Types of application or development that require this information

  • Householder development in flood zones 2 and 3 (including sheds, garages and games rooms etc within the curtilage)

Excluding proposals for:

  • External alterations to buildings that create no new floor space

What information is required?

A Flood Risk Assessment must be submitted which includes:

  1. An assessment of the flood risk for the development (considering all sources of flooding not just rivers and including an allowance for climate change). If your extension is in an area with increased flood risk as a result of multiple minor extensions in the area, you need to include an assessment of the off-site flood risk. Check with the Drainage Team if this applies to your development.
  2. The estimated flood level for your development: the 1 in 100 year river flood level. Plans must be provided showing the finished floor levels and estimated flood levels. Floor levels must either be no lower than existing floor levels or 300 millimetres above the estimated flood level. If the floor levels aren’t going to be 300mm you need to check with your local drainage authority if you also need to take flood resistance and resilience measures. The assessment must have all levels in relation to Ordnance Datum (the height above average sea level). You may be able to get this information from Ordnance Survey. If not you’ll need to get a land survey carried out by a qualified surveyor.
  3. Details of your flood resilience and resistance plans. Plans need to show how you’ve made efforts to ensure the development won’t be flooded by surface water runoff, for example by diverting surface water away from the property or by using flood gates.

Make sure your flood resistance and resilience plans are in line with the guidance on improving the flood performance of new buildings.

Further information

Find out what flood zone you are in:

The map displays the most up-to-date data directly from the Environment Agency in relation to the main river network, flood zones 2 and 3, areas of historic flooding, areas at risk of surface water flooding, areas which are identified for flood risk management, and areas where natural processes could be used to reduce flood risk.

The map also includes the spatial extent of flood zone 3b (the functional floodplain) which has been defined by the Council in conjunction with the Environment Agency as part of the SFRA. The full SFRA report is available on the Council's website.

Users of this map should also check the Environment Agency's Flood Map for Planning.

Please note that as of 28 January 2025 the EA has published its new Risk of Flooding from Surface Water maps.

Policy driver

  • National Planning Policy Framework - Chapter 14: Meeting the challenge of climate change, flooding and coastal change
  • National Planning Practice Guidance: Flood risk and coastal change
  • Core Strategy - Policy EN7: Flood Risk

Stay connected

Sign up for email updates about planning and building control

Other pages in this section