Flood zone restrictions on Class Q and Class MA
Flooding risk is a listed prior approval matter for both classes, and a council can refuse on it alone. What evidence to submit and which sites cannot convert.
Flood risk prior approval class ma questions arise because the permitted development right is not unconditional. Both Class MA and Class Q in Part 3 of Schedule 2 to the General Permitted Development Order 2015 require the local planning authority's prior approval on a defined list of matters, and flooding risks in relation to the building is one of the items on both lists. An authority can refuse prior approval on that ground alone.
So a barn in Flood Zone 3 does not convert itself just because the class otherwise fits.
Flood risk as a prior approval matter
Prior approval is not planning permission. The Order grants the permission, subject to the developer first obtaining the authority's approval on specified matters. The authority cannot look at anything else, which cuts both ways: it cannot refuse on design in a class where design is not listed, and it must consider flooding where flooding is listed.
For Class MA, the change of use from Class E commercial, business and service use to dwellinghouses, the prior approval matters include transport impacts, contamination risks, flooding risks, noise from commercial premises, the provision of adequate natural light to all habitable rooms, and in specified areas the effect of the loss of the ground floor use.
For Class Q, the change of use of an agricultural building to dwellinghouses, the matters include transport and highways impacts, noise, contamination, flooding risks, whether the location makes the residential use impractical or undesirable, and design or external appearance.
Read the current text of the class before advising anyone. Both classes have been amended, and the Class Q amendments in particular changed the qualifying criteria as well as the process, as set out in the 2024 amendments to Class Q barn conversions.
Which classes list it
Not every class in Part 3 lists flooding. That is worth checking rather than assuming, because the scope of prior approval varies class by class and an authority that raises a matter outside its list is acting beyond its powers.
| Class | Change | Flooding a prior approval matter |
|---|---|---|
| Class MA | Class E to dwellinghouses | Yes |
| Class Q | Agricultural building to dwellinghouses | Yes |
| Class R | Agricultural building to a flexible commercial use | Check the current text |
| Part 1 householder classes | Extensions and outbuildings | No prior approval on flooding |
Where flooding is not a listed matter for the class you are using, the authority cannot refuse prior approval on that basis. It can still be relevant to building regulations, to insurance and to the practical decision about whether the conversion is a sensible investment.
Environment Agency consultation on prior approval
The procedural paragraph governing prior approval applications in Part 3 requires the authority to consult the Environment Agency where the development is in an area within Flood Zone 2 or 3. That consultation carries a response period, and it is the single most common reason a prior approval determination runs to the end of its statutory period.
Plan for it. The determination period for prior approval is fixed, and where the authority does not determine within it the development may proceed in accordance with the application, so the timetable matters commercially. An application submitted without the flood information the Environment Agency needs invites a holding objection, and a holding objection usually produces a refusal rather than an extension.
Speak to the authority before submitting where the site is in Zone 2 or 3. Ask what it expects to see on the flooding matter, because practice varies and the class does not specify a document.
Evidence expected at this stage
There is no prescribed form of flood evidence for a prior approval application, which leads some applicants to submit nothing and others to submit a full assessment. The proportionate answer sits between.
What a well-prepared submission contains:
- The flood zone from the Flood Map for Planning, with the date the map was checked.
- Surface water and reservoir risk from the published long term flood risk service.
- Modelled flood levels for the relevant event, obtained from the Environment Agency, with the climate change allowance applied for the relevant river basin district and the lifetime of the development.
- Existing ground and floor levels surveyed to ordnance datum, not scaled from a drawing.
- The proposed internal layout showing sleeping accommodation and refuge above the design flood level.
- Access and egress routes with levels along their length.
- Proposed resistance and resilience measures, with a note of what is fixed and what depends on occupier action.
Where the building sits in Zone 3 or where modelled levels are close to floor level, a full Flood Risk Assessment is the sensible document even though the class does not name one. It is the format the Environment Agency reads.
Finished floor levels and safe access
Two technical points decide most flood refusals on conversions.
Finished floor levels are usually expected to sit above the design flood level plus freeboard. On a new build that is a design decision. On a conversion it often is not, because raising the floor of an existing barn reduces the headroom below what the building regulations require, and lowering the ground outside changes the flood behaviour around the building. The constraint is physical, and no amount of policy argument moves it.
Safe access and egress is the second. National flood risk policy expects occupants to be able to leave safely, or to have a safe refuge, during the design event. A single-storey building with no first floor and an access track that floods to a depth and velocity that is unsafe on foot gives the authority very little to work with.
Where a first floor exists or can be created within the existing envelope, a refuge above the flood level plus a flood warning and evacuation plan is the usual package. Where the building is single storey, the honest advice is often that the flooding matter cannot be resolved.
Note: flood resilience measures such as raised sockets, closed cell insulation and solid floor construction reduce damage. They do not make an unsafe site safe, and presenting them as the answer to a safety objection rarely works.
Where the sequential test comes in
The sequential test in national flood risk policy directs development towards areas at lower risk, and residential use is classified as more vulnerable, so it sits awkwardly in higher flood zones.
Whether the formal sequential test applies to a prior approval application is contested, because prior approval is not an application for planning permission and the authority's consideration is confined to the listed matters. Practice varies between authorities, and some ask for a sequential test while others treat flooding risk as a site-specific technical matter only.
Establish the position with the authority before submitting rather than arguing it afterwards. Where a test is asked for, the approach and the area of search are set out in the Sequential Test (Flood), and the search area is usually the point of dispute.
For a full planning application on the same site, the position is clearer: the sequential test applies to proposals for more vulnerable uses in Zones 2 and 3, and the exception test may follow.
Why some sites cannot use the right at all
It is worth saying plainly. A proportion of agricultural and commercial buildings in flood risk areas will not convert under these rights, and no amount of documentation changes that.
The combinations that usually fail are a single-storey building in Flood Zone 3 with no refuge, a site in the functional floodplain where more vulnerable uses are not appropriate in principle, an access route that is impassable during the design event, and a building where the required floor level cannot be achieved within the existing structure.
Where that is the position, the alternatives are a full planning application for a scheme that addresses flood risk by design, a different use that is less vulnerable, or accepting that the building stays as it is. A full application at least allows the authority to weigh other planning benefits, which prior approval does not.
Before committing, read the procedure carefully, because the timetable and the limits on what can be submitted differ from an ordinary application. The mechanics are set out in how the prior approval procedure actually works.
This is general guidance, not legal advice. A lawful development certificate is the only formal way to confirm that works are lawful, so check the position with your local planning authority or a qualified professional before relying on it. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval. To see which documents a conversion on a flood-constrained site needs, enter your postcode on PlanScope.
Frequently asked questions
Can a council refuse prior approval because of flood risk?
Yes, where flooding risks are a listed prior approval matter for the class being used, as they are for both Class MA and Class Q. Prior approval confines the authority to the matters the Order lists, so it cannot refuse on design in a class where design is not listed, but it must consider flooding where flooding is listed.
Does the Environment Agency get consulted on a prior approval application?
The procedural paragraph governing prior approval in Part 3 requires the authority to consult the Environment Agency where the development is in an area within Flood Zone 2 or 3. That consultation has its own response period and is a common reason a determination runs to the end of the statutory period, so submit the flood information with the application.
Do I need a full Flood Risk Assessment for prior approval?
The class does not prescribe one, and a proportionate submission is often enough in Flood Zone 1 or on a site well above modelled levels. Where the building is in Flood Zone 3, or where modelled levels sit close to floor level, a full assessment is the sensible document because it is the format the Environment Agency reads and responds to.
Does the sequential test apply to prior approval?
It is contested. Prior approval is not an application for planning permission and the authority's consideration is confined to the listed matters, so practice varies between authorities. Some ask for a sequential test and others treat flooding as a site-specific technical matter. Establish the local position before submitting rather than arguing it afterwards.
Can flood resilience measures overcome a safety objection?
Rarely. Raised sockets, closed cell insulation and solid floor construction reduce damage when water enters, which is a different thing from making occupants safe during a flood. Where the objection is about safe access, egress or the absence of a refuge above the design flood level, resilience measures do not answer it.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.