Written by Nikki O’Hagan, 18th July 2024

Introduction

In a recent appeal decision, an Inspector has taken a refreshingly pragmatic and common sense approach to application of the flood sequential test for replacement dwellings. We expect this to have positive implications for future replacement dwelling applications in flood risk areas. It may also have a similarly positive impact on other types of replacement buildings.

Read on to find out more.

What is the flood sequential test?

In short, the flood sequential test seeks to locate new development in areas with the lowest flood risk. Development in areas with greater flood risk will only be supported if there is no suitable land available in areas with lower flood risk. The aim of the sequential test is to investigate and establish whether a proposed development could be relocated to a site with lower flood risk.

How does it work?

If a site is within an area that is at risk of flooding, the applicant must carry out a search for “reasonably alternative” sites. They should look for sites that have the lowest flood risk first. If there are no such sites, they should consider sites with medium flood risk next, and so on. The sequential test is a written report that contains the results of the applicant’s search alongside detailed assessment of the potential alternative sites.

The sequential test is only passed if there are no “reasonably available” sites within areas of lower flood risk.

What does “reasonably available” mean?

A “reasonably available” site:

• Is in a location that is suitable for the proposed development; and
• Has a reasonable prospect of being developed at an appropriate time.

A reasonably available site could include a single site, part of a larger site or a series of small sites. Ownership is irrelevant.

Applicants should use a range of sources to search for alternative sites, including:

• Local planning documents that may have allocated or identified sites for development.
• Estate agencies and online property registers like Zoopla, OnTheMarket and Rightmove.
• Local registers of sites with suitable planning permission.

It is for the applicant to argue, in the context of a sequential test, that a site is or is not “reasonably available” for the proposed development. However, the decision-maker* will reach their own view, based on the facts of the case and the applicant’s arguments.

*at application stage, that’s the Local Planning Authority which is normally your local council. At appeal stage, it’s the Planning Inspectorate.

What is the search area?

It is the Local Planning Authority’s responsibility to determine the area of search for any sequential test. In our experience, LPAs commonly expect the search area to consist of the whole local authority area.

In some circumstances, the search area is likely to be smaller. For example, if the proposal relates to a school then the search area ought to be equal to the school catchment area. This would also apply to other types of development with specific catchment areas such as medical centres.

In addition, if a development is clearly and directly related to a specific local area or local need – such as for affordable housing – you may be able to agree a smaller search area with your Local Planning Authority.

What counts as flood risk?

Sequential tests are required for most development (see exemptions below) in “areas at risk of flooding”. This includes land:

• In flood zones 2 and 3.
• In flood zone 1 where the LPA’s Strategic Flood Risk Assessment (SFRA) shows the area will be at increased risk of flooding during its lifetime. This often due to climate change.
• Subject to sources of flooding other than rivers or sea. This could include surface water flooding.

It’s easy to find out whether your site is in flood zone 2 or 3. Simply click the button below and enter your postcode. You may require professional assistance to check for all other sources of flooding, however. It’s worth speaking to your Local Planning Authority in the first instance but there may be a charge for their advice.

Exemptions

Some developments are exempt from the need to apply the sequential test no matter where they are located. This includes:

• Householder development – home extensions, domestic outbuildings and garages etc.
• Small non-residential extensions – max. footprint of 249 square metres.
• Certain changes of use (but not all).

Sites that have been allocated for development in a Local Plan following application of the sequential test by the Local Planning Authority are also exempt.

Some developments do not need to apply the sequential test but do still need to apply a different test known as the exception test. Other developments must apply both.

Exception test

It’s worth being aware that there is another test that may need to be applied in areas at risk of flooding in addition to the sequential test. This is known as the exception test. To pass the exception test, an applicant must demonstrate that the development:

• Provides wider sustainability benefits to the community that outweigh the flood risk; and
• Will be safe for its lifetime, without increasing flood risk elsewhere.

Generally speaking, the exception test will need to be applied whenever the sequential test is passed. The development will only be able to proceed if both tests are passed.

The appeal decision

There are only a few types of development that are exempt from the need to apply the sequential test. These are clearly set out in national policy. If your development is not one of the limited exemption types, you will be expected to carry out a sequential test. Because flood risk is a serious matter, decision-makers do not generally make any exceptions to this.

However, a recent appeal decision has established one further exception. The appeal concerned a proposal for a replacement dwelling. Replacement dwellings are not exempt from the need to apply the sequential test. However, no sequential test had been carried out by the applicant in this case.

The Inspector who decided the appeal confirmed the requirement to apply the sequential test for replacement dwellings. However, the Inspector also recognised that the proposed replacement dwelling would lessen the risk of flooding for its occupants. This was due to a number of factors, including the replacement dwelling’s superior construction and raised floor level.

The Inspector found that the exception test was passed and decided that the benefits of a reduction if flood risk were sufficient to outweigh the lack of a sequential test. On this basis, the appeal was allowed.

What are the implications for replacement dwellings?

It may no longer be necessary to apply the sequential test for replacement dwellings. Instead, it should be enough to demonstrate that the replacement dwelling would be more resilient to flooding than the existing dwelling and so would lessen the risk of flooding for its occupants. You will still need to provide some form of flood report to demonstrate exactly how the replacement dwelling improves flood resilience and reduces flood risk.

This may also apply to other types of replacement buildings and structures. Ultimately, the primary aim of flood policy is to keep people and property safe from flooding. If you can provide evidence that your proposed development actively reduces or removes an existing flood risk then decision-makers ought to respond in a positive and common sense way.

If you require assistance with a replacement dwelling scheme or a flood issue, please get in touch today. Our initial advice is always free of charge.