Permitted Development

Permitted development rights allow you to improve or extend your home or building without the need to apply for full planning permission. It also covers change of use to residential and prior approvals.

If that building is in a Flood Zone you still need a Flood Risk Assessment to get development permission.

We know that this is an added expense, so we offer competetive, clear pricing to try and support your plans, without compromising on quality and delivery.

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Does Permitted Development require a Flood Risk Assessment?

All development in England, if located in Flood Zone 2, 3, or a critical drainage area, is required to be supported by a Flood Risk Assessment at planning. If the development has a site area of greater than 1 hectare and is located in Flood Zone 1, a Flood Risk Assessment would be required. This policy applies to permitted development and change of use developments.

The approach applied to each development can be different due environmental conditions, flood zone, type of development, and local policy.

This reinforces why it is important to work with a specialist to make sure you have the right Flood Risk Assessment specific to your development!

Read More about different Permitted Development types and the requirements of flood risk below.

Flood Risk Experts

Daniel Cook
BSc MSc C.WEM MCIWEM
Director
I’m a Chartered Water and Environment Manager and specialist Flood Risk Consultant, working in the environmental consultancy sector since 2011. Specialist Subject: flood risk policy!
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Nick Darling-Drewett
BSc MCIWEM AMIEnvSC
Principal Flood Risk Consultant
I’m a Principal Flood Risk Consultant at Aegaea with extensive experience in producing FRAs and drainage strategies. Specialist Subject: FRAs
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Douglas Swinbanks
MEng
Principal Flood Risk Engineer and Hydrologist
I’m a Principal Flood Risk Engineer and Hydrologist based in Edinburgh. Specialist Subject: Scotland Policy and Integrated Catchment Modelling.
> View Profile

Class M

Mixed use to residential

Class O

Offices to residential

Class Q

Agricultural buildings and barns to residential

Prior Approval

Change of use

Need a Flood Risk Assessment? Our team are ready to support you.

Class M – Mixed Use to Residential

If your site is mixed-use, there is a potential that under Permitted Development – Class M planning legislation, it could be converted or ‘change of use’, to provide residential dwellings or residential units.

​To support this change of use, the existing site is to comprise of a ‘mixed use’ of retail classes (Use Class A). These include shops, retail outlets, food and drink, drinking establishments, hot food and take away, professional services or financial services such as betting offices/payday loan shops.

It is important to note that there are specific permitted development rights for changes of that mixed-use. It is strongly advised that all applications be checked with a local authority before starting work or engagement with a recognised planning specialist (which can be found through the Royal Town Planning Institute (RTPI)).

​Where the proposal is a change of use, from mixed-use to residential (Use Class C3), they are subject to limitations and conditions, including the need to apply for prior approval based on the following.

  • transport and highways impacts

  • contamination and flooding risks

  • impact on the adequate provision of services and sustainability of the shopping area

  • design or external appearance of the building (where building operations are required)

​Therefore, to support a permitted development application and prior approval there is a requirement to provide supporting assessments, as above. One of those is a Flood Risk Assessment.

​Our expert team can provide a Flood Risk Assessment to advise on whether your site is at risk of flooding.  In addition, the team can advise and support through the design process if the site was to be at risk of flooding. We can advise of mitigation measures that could be required for the development to pass the exception test.

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Class O – Offices to Residential

Development within previously recognised professional areas or places of work to residential use has become more common due to changes allowing for the change of use to residential units or dwellings. Offices are by far the most popular permitted development opportunity in the GPDO (General Permitted Development Order). Whilst this requires a prior approval application it has been carried out many times within England.

​It is possible under the Permitted Development of Class O to support this change of use. Class O is for Offices (Use Class B1a) permitted to change of use to provide residential units or dwellings (use Class C3).  This is subject to limitations and conditions, including the need to apply for prior approval based on the following;

  • transport and highways impact

  • contamination and flooding risks

  • impacts of noise from commercial premises on the intended occupiers of the development.

​​Our expert team can provide a Flood Risk Assessment to advise on whether your site is at risk of flooding.

In addition, the team can advise and support through the design process if the site were to be at risk of flooding elements to be considered would be safe access/egress during the event of a flood, where the residential units be located in the building as well as supporting infrastructure plant rooms, etc. We can advise of mitigation measures that could be required for the development to pass the exception test.

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Class Q – Agricultural Buildings/Barns to Residential

This permitted development is focused on the change of use of Agricultural Buildings to Residential (Use Class C3). This development can also include specific building operations reasonably necessary for the conversion to function as a dwelling house:

  • the installation or replacement of:

  • windows, doors, roofs, or exterior walls, or

  • water, drainage, electricity, gas, or other services

  • partial demolition to the extent reasonably necessary to carry out building operations

​It is strongly advised that all applications be checked with a local authority before starting work or engagement with a recognised planning specialist – Royal Town Planning Institute (RTPI), to advise if Class Q is appropriate for you and your development.

Class Q has certain limitations and conditions, including:

  • Creation of no more than five separate dwelling houses (including any previously created under this right)

  • Up to three of the five can be ‘larger dwelling houses’ (floor space of 100-465m2).

  • ‘Larger dwelling houses’ can total no more than 465m2 of floor space (including any previously created under this right) and no single dwelling house can exceed 465m2.

​This also includes the need to apply for Prior Approval based on the:

  • transport and highways impacts

  • noise impacts

  • contamination and flooding risks

  • location or siting of the building

  • the design or external appearance of the building (where building operations are required)

​Like the other change of use classes discussed above, there are conditions to be met before a prior approval can be permitted. There is the opportunity for a local planning authority to issue a refusal if the conditions demonstrate that the change of use is not favourable or viable. Of the conditions listed as per the bullet points above, a Flood Risk Assessment is required to better understand the flooding risks to a Site and existing buildings.​

In our experience, due to the rural nature of agricultural sites the data available to support a Flood Risk Assessment can vary. It is therefore recommended that whilst engaging with your local authority, architect, or planning specialist, you should also have discussions with a flood risk consultant.

Our consultants can advise on what options are available to support the development if the data available is poor in quality. Alternatively, our team is also able to advise if the quality of the data is fit for purpose.

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Prior Approval – Paragraph W – Part 3

If you’re looking to submit a prior approval application under Part 3 – Changes of Use, then you will need to comply with all elements of Paragraph W. Failure to comply with Paragraph W could result in your application not being validated or refused. It is strongly advised that all applications be checked with a local authority before starting work or engagement with a recognised planning specialist – Royal Town Planning Institute (RTPI) to advise if prior approval is appropriate for you and your development.

​Prior Approval – Paragraph W under Part 3, Paragraph W procedure applies to Part 3 of Schedule 2. Part 3 includes changes of use from agricultural to residential and office to residential. Paragraph W(3) provides that a local planning authority may refuse an application for prior approval if the proposal does not comply with any applicable conditions, limitations, or restrictions.

​Where the application relates to prior approval as to the flooding risks on the site, on receipt of the application, the local planning authority must consult the Environment Agency where the development is

​(a) in an area within Flood Zone 2 or Flood Zone 3; or

​(b) in an area within Flood Zone 1 which has critical drainage problems and which has been notified to the local planning authority by the Environment Agency.

​Our expert team can provide a Flood Risk Assessment to advise on whether your site is at risk of flooding by confirming if your site is located within Flood Zone 2 or 3. In addition, they can further advise if the site is located in a Critical Drainage Area.

Should it be identified that the development site is located within one of these two criteria, Aegaea can advise and support you through the design process. We can determine if the site were to be at risk of flooding and whether there is safe access/egress during the event of a flood.

Once instructed we can further advise of possible mitigation measures that could be required for the development to pass the exception test. We work collaboratively with our clients and promote regular communication, especially if the flood risk to a site requires design changes. It is important to identify mitigation options early in the project and cooperatively work through any clashes with the aspiration to achieving a successful project.

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