Do I need a flood risk assessment for my extension?

If your property is in Flood Zone 2 or 3, yes — you will need a flood risk assessment to submit with your planning application. If you're in Flood Zone 1, you typically don't need one unless your local council has identified other flood risk at your site.

How do I find out what flood zone my property is in?

Enter your postcode in our free tool above. We check the Environment Agency's Flood Map for Planning to determine whether your site is in Flood Zone 1 (low), Flood Zone 2 (medium), or Flood Zone 3 (high probability).

What is the difference between Flood Zone 1, 2, and 3?

Flood Zone 1 has less than 0.1% annual probability of flooding. Flood Zone 2 has between 0.1% and 1% probability from rivers (or 0.5% from the sea). Flood Zone 3 has greater than 1% probability from rivers (or 0.5% from the sea). The higher the zone, the more stringent the planning requirements.

Can I still build in a flood zone?

Yes. Thousands of developments are approved in Flood Zones 2 and 3 every year. The key is providing a robust flood risk assessment that demonstrates your development will be safe for its lifetime. Different types of development face different requirements — extensions are generally easier to get approved than new builds.

How much does a flood risk assessment cost?

Costs depend on the flood zone, development type, and complexity. Desktop FRAs for extensions and minor works are the most affordable. Detailed FRAs with hydraulic modelling cost more. We provide fixed-fee quotes with no hidden charges.

What is the Sequential Test?

The Sequential Test requires you to demonstrate that there are no reasonably available alternative sites in a lower flood zone for your development. It applies to new builds and changes of use, but not to minor development like extensions.

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Do I Need a Flood Risk Assessment?

Enter your postcode to check your flood zone and find out whether you need an FRA for your planning application. Takes 60 seconds.

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Common Questions

Frequently asked questions

Do I need a flood risk assessment for my extension?: If your property is in Flood Zone 2 or 3, yes — you will need a flood risk assessment to submit with your planning application. If you're in Flood Zone 1, you typically don't need one unless your local council has identified other flood risk at your site.
How do I find out what flood zone my property is in?: Enter your postcode in our free tool above. We check the Environment Agency's Flood Map for Planning to determine whether your site is in Flood Zone 1 (low), Flood Zone 2 (medium), or Flood Zone 3 (high probability).
What is the difference between Flood Zone 1, 2, and 3?: Flood Zone 1 has less than 0.1% annual probability of flooding. Flood Zone 2 has between 0.1% and 1% probability from rivers (or 0.5% from the sea). Flood Zone 3 has greater than 1% probability from rivers (or 0.5% from the sea). The higher the zone, the more stringent the planning requirements.
Can I still build in a flood zone?: Yes. Thousands of developments are approved in Flood Zones 2 and 3 every year. The key is providing a robust flood risk assessment that demonstrates your development will be safe for its lifetime. Different types of development face different requirements — extensions are generally easier to get approved than new builds.
How much does a flood risk assessment cost?: Costs depend on the flood zone, development type, and complexity. Desktop FRAs for extensions and minor works are the most affordable. Detailed FRAs with hydraulic modelling cost more. We provide fixed-fee quotes with no hidden charges.
What is the Sequential Test?: The Sequential Test requires you to demonstrate that there are no reasonably available alternative sites in a lower flood zone for your development. It applies to new builds and changes of use, but not to minor development like extensions.

Do I Need a Flood Risk Assessment?

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2 Your flood zone

What type of development are you planning?

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Frequently asked questions

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