Basement developments

Where your proposed development includes a new or extended basement you will need to submit a detailed technical statement assessing the impact of the development on drainage, flooding, groundwater conditions and structural stability.

This information should be contained within a Basement Impact Assessment (BIA) which is specific to your site and proposal.

The Camden Local Plan 2017 includes policy A5 on basement development which updates and expands former basement policies. It places specific restrictions on the scale of basements and their impact.

Updated guidance 2018

  • Planning Guidance:  On 26th March 2018 the Council formally adopted Camden Planning Guidance : Basements. The Guidance was prepared to support the policies in the Camden Local Plan 2017. It should be read in conjunction with the relevant policies in the Local Plan. The Guidance replaces Camden Planning Guidance 4: Basements and Lightwells (July 2015).
  • Audit review: Basement Impact Assessments are technical documents which must be prepared in accordance with planning policies and guidance and submitted with planning applications for basement development. The Council obtains independent audits of BIAs from Campbell Reith Consulting Engineers in order to ensure that they meet the technical policy requirements. In 2017 officers reviewed the BIA audit  process with Campbell Reith (PDF) in order to ensure the process is relevant, efficient and effective.
  • As a result of the review Camden has produced a ‘BIA pro forma’ and a help note on ‘Defining the Scope of Engineering input to preparing BIAs’ in order to help applicants who are preparing planning applications for basement development.

The information below provides further details about what information this document should include, how to submit it to us and where further information can be found.

What information should be included when submitting applications for basement developments?

When submitting applications for basement developments, the level of technical information required will vary according to the type of the development. To help applicants and engineers understand the technical requirements of the BIA process, we have produced  guidance and a Camden BIA pro forma.  

BIA pro-forma :

  • The pro forma is for use by applicants and engineers in the preparation of Basement Impact Assessments.
  • The document provides helpful reminders and summaries of the topics that must be addressed in BIAs if they are to properly address the basement policy requirements.
  • The pro forma is based on detailed knowledge of Camden Planning Guidance and the Local Plan Policy A5.
  • It is not intended for use as a template, but applicants and engineers are encouraged to use the headings provided and include information on all relevant topics under those headings to ensure that they meet all of the Council’s expectations.
  • Use of non-standard formats may result in delay or additional costs associated with the independent audit.

Defining the scope of engineering input into BIAs

  • No matter what scale of basement work is proposed, the development will need to be planned with engineering input, and this must be evident in the Basement Impact Assessment.
  • This note is relevant to anyone who is considering making a planning application for basement development and is intended to provide guidance on the scope of services that are needed from a Structural Engineer in the preparation of BIAs.
  • The note can also be used by engineers who are not familiar with Camden’s basement policy, to clarify and inform their role.

Before submitting your Basement Impact Assessment

Before you submit your planning application for basement development you should complete the necessary sections of the Audit Instruction Form (see below). We require a completed Instruction Form as part of the BIA Audit process. The Form also sets out a helpful checklist of information normally required in a BIA and you are encouraged to complete it when preparing your BIA for submitting with your planning application

All technical reports should be prepared by a suitably qualified chartered engineer or chartered geologist who is a member of the relevant professional body. Refer to Section 6.7 of the ARUP Camden geological, hydrogeological and hydrological study for details. Section 8 of the ARUP study sets out a list of issues you need to assess in your report.

How does Camden assess applications for basement development?

In order to provide the Council with greater certainty over the potential impacts of your basement development, we will generally require an independent technical audit (independent verification) of your Basement Impact Assessment, as set out in Camden Planning Guidance: Basements. The Council has chosen Campbell Reith as its single framework provider for the audit service – an approach agreed by the Cabinet Member for Sustainability, Transport and Planning in September 2014 as part of a ‘Strategy for the Procurement of a Provider of a Basement Impact Assessment service’ (PDF).

How do I submit an application for a basement development?

If you apply for planning permission online using the Planning Portal, you will be given the opportunity to upload a general statement on meeting the terms of Camden's Local Plan Policy A5 after you have completed the relevant application forms.

Before uploading any files please read our guidance notes for submitting electronic files with planning applications (PDF)

Further information and guidance on basement developments:

Camden BIA Pro Forma  (Word document)
Camden Planning Guidance (PDF)
Guidance on the scope of engineering services in preparing BIAs  (PDF)
Camden Local Plan 2017
ARUP Camden geological, hydrogeological and hydrological study PDF
Audit Instruction Form (Section B) (Word document )
Audit process Terms of Reference (PDF)