ST / ET
Sequential Test and Exception Test
These are policy arguments, not hydraulic ones. The Sequential Test asks whether the development could reasonably go somewhere at lower flood risk. The Exception Test only follows if it could not, and asks whether the wider benefits justify proceeding.
- When it is needed
- Most development in Flood Zone 2 or 3, and where a more vulnerable use is proposed. Householder extensions and many changes of use are exempt from the Sequential Test, though an FRA is often still required
- Who asks for it
- The planning authority, which carries out the test using the evidence you submit
- Watch for
- A search area that has not been agreed with the case officer is the most common reason a Sequential Test is rejected
Agree the search area before anything else
The Sequential Test asks whether the development could reasonably go somewhere at lower flood risk. Everything therefore depends on how widely you are expected to look — and that is the planning authority’s call, not yours.
More sequential tests fail on this than on any technical point. We put the proposed search area and the site selection criteria to the case officer in writing at the outset, so the assessment is built on a basis they have already accepted.
Evidence, not assertion
Within the agreed area we work through the sites that were genuinely available during the relevant period, drawing on the local land availability assessment, the brownfield register and the market at the time, and record why each was discounted — size, availability, deliverability or suitability for the use proposed.
Discounting a site because it is not the one your client owns is not a reason. Discounting it because it cannot accommodate the floorspace the scheme needs, evidenced, is.
When the Exception Test follows
The Exception Test only arises where the Sequential Test has been passed and policy still requires it. It has two limbs, and both must be satisfied: that the development delivers wider sustainability benefits to the community which outweigh the flood risk, and that it will be safe for its lifetime without increasing flood risk elsewhere.
The second limb comes straight out of the flood risk assessment, which is why the two documents have to be written to agree with one another. The first is a planning argument, and we prepare it to sit alongside your planning statement rather than duplicate it.
When you do not need one
Householder extensions and many changes of use are not subject to the Sequential Test. That does not mean nothing is required — a flood risk assessment is frequently still expected, and the safe-access question does not go away.
If you have been asked for a sequential test on a scheme that looks exempt to us, we will tell you before quoting for one.
Often needed alongside
Other reports for the same application
Not sure what your application needs?
Send us the site address and a line about what you are proposing. We will tell you which reports the authority is likely to ask for, and what they will cost — usually within one working day.