Understanding and assessing flood risk
Check if the sequential and exception tests apply
A sequential test1 is required for major and non-major development – (check the development class section above) if it is:
- in flood zone 2 or 3
- in flood zone 1 and your LPA’s SFRA shows it to be at risk of flooding from rivers or the sea in the future
- at risk of flooding from other sources, or could be in the future
The sequential test compares your proposed site with other available sites. Its aim is to steer new development to areas with the lowest risk of flooding.
Development in flood risk areas is only exempt from the sequential test if it is a:
- householder development like residential extensions, conservatories or loft conversions
- small non-domestic extensions with a footprint of less than 250 square metres
- change of use (except changes of use to a caravan, camping or chalet site, or to a mobile home or park home site)
- development on a site allocated in the development plan through the sequential test, and:
- the proposal is consistent with site’s allocated use; and
- there have been no significant changes to the known level of flood risk to the site, now or in the future, which would have affected the outcome of the test
You should speak to the LPA early to discuss the sequential test and determine an appropriate area of search for the test. It is for the LPA to consider whether the test is passed, with reference to the information it holds on land availability. You should also include information with your application to identify any other ‘reasonably available’ sites within the area of search that have not already been identified by the LPA, such as sites currently available on the open market. The LPA may also require you to check on the current status of alternative sites to determine if they can be considered ‘reasonably available’. Refer to guidance on Applying the sequential test to individual planning applications.2 Speak to the LPA to find out what further information may be needed on the sequential test.
If the sequential test can be satisfied you need to check if the exception test is also needed. The exception test is needed for developments with a vulnerability classification3 of:
- ‘highly vulnerable’ in flood zone 2
- ‘more vulnerable’ in flood zone 3a
- ‘essential infrastructure’ in flood zone 3a or 3b
You will need to provide the evidence the LPA needs to check if:
- the development would provide wider sustainability benefits to the community that outweigh the flood risk
- the development will be safe for its lifetime taking account of the vulnerability of its users, without increasing flood risk elsewhere
- the development will reduce flood risk overall, where possible
The LPA can refuse planning permission if the sequential and exception tests are not done or not satisfied.
Refer to guidance on How it can be demonstrated that wider sustainability benefits to the community outweigh flood risk?4 More information can also be found in How can it be demonstrated that development will reduce flood risk overall?5 and Reducing the causes and impacts of flooding6.