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Flood Risk Assessments and Permitted Developments

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Permitted development rights (PDRs) are the right to make specific changes to a building without necessity of requesting planning permission. Before certain PDRs are applied, the builder must first get “prior approval” with respect to specific elements of the project from the Local Planning Authority (LPA).
Do I need to submit a risk assessment of floods when I apply for approval prior to the application?

If the project you are working on falls under one of these categories and your building/land is in the flood zone 2 or 3, it’s a lawful requirement that you submit a site-specific assessment for the risk of flooding to the local authority. Other reports may be requested by the local authority such as reports on contaminated land or mitigation documents, for example the decontamination plan. If the project is deemed to be located in a flood zone 1 it is unlikely that the project will cause any flooding issues unless the region has serious drainage problems or is at risk of surface water or groundwater flooding.

Mixed Use Class M
Office to Residential Class O
Storage and Distribution to Residential – Class P
Agricultural Buildings to dwellings Class Q
Commercial Buildings for Agriculture – Class R
Buildings for Agricultural use to nurseries or schools – Class S
Buildings and land to nurseries, schools, and other nurseries – class T

Planning Policy Guidance (PPG) is also stated to help LPAs in determining if the prior approval is needed for areas that are at risk of flooding, applicants must provide:

“an assessment of the flood risk. This will show how flood risk to the property will be managed so that it remains secure throughout its entire life.”

What kind of changes are not considered to be flood risk assessment

There isn’t a requirement for assessments of flood risk to be carried out for the following categories:

Improvement, expansion or alteration of Class A
Additions to the roof- Class B
Other roof modifications-Class C
Porches-Class D
Outbuildings Class E

The LPA might want to verify that any modifications to the footprint of the house, particularly, do not increase the risk of flooding neighboring properties with permeable building materials.

Do I require planning permission to improve my driveway?

Permeable (or porous) driveways of all sizes that allow water to flow through them, such as gravel, concrete block paving, porous asphalt or permeable asphalt, do not need planning permission.

Planning permission is required for traditional impermeable driveways that have a surface area exceeds five metres. The driveways won’t allow water to flow to an area that is permeable. In order to prevent flooding risk to neighboring third parties, a sustainable drainage report may be required.

This is only applicable to houses, not maisonettes, flats or houses that have been converted by granting development rights.

The permitted development rights only can be used for front gardens. you might require permission to build fences, walls, gates or a kerb that has been dropped.

What should I do if the development is situated in an area that is prone to flooding?

Where the proposed permitted development is situated in a flood-risk zone the applicant must show a map of the final floor levels as well as the flood levels estimated.

Government standing advice stipulates that floor levels must be either no lower than floor levels currently in use or 300mm above the estimated flood level.

There may be a need to take extra measures to ensure that your buildings are resilient and flood resistant. These measures must be in accordance with the guidelines for improving flood performance of new buildings.

It is essential to include in your plans the steps you take to ensure that the development isn’t submerged in water. This could include the use of flood barriers or diverting surface water away.

If your minor extension is in an area with increased risk of flooding as a result of multiple minor extensions in the area, you will have to make an assessment of the risk to the flood off-site. If this applies to you the area, your LPA will notify you.

Can development that is allowed to continue be stop?

LPAs can suspend their development rights in their territory in certain situations. This is in accordance with Article 4 of 2015 Order. Notification must be given to the Secretary of State. He has broad powers to amend or cancel article 4.

An LPA could consider adopting an article 4 directive to “protect local amenities or the health and well-being” when considering flooding risks posed by permitted development.

Clearer Pictures

We know how surface, river and groundwater flooding affect property and development sites. Our flood risk experts will provide advice regarding flood zones, limitations and possible weaknesses that could impact your client’s development permit.