The Construction (Design and Management) Regulations 2015 (CDM 2015) govern health, safety, and welfare on construction projects in Great Britain. They apply to all construction work, including new builds, refurbishments, maintenance, and demolition — regardless of size. Understanding your duties as a client is essential to keeping your project legally compliant and your workers safe.
Who Is a 'Client' Under CDM 2015?
A client is any organisation or individual for whom a construction project is carried out. This includes commercial clients (businesses and organisations) and domestic clients (individuals having work done on their own home). Commercial clients have the most extensive duties under the Regulations, whilst domestic clients' duties are generally passed to the contractor or principal contractor.
When Must You Appoint a Principal Designer and Principal Contractor?
When a project involves more than one contractor — which is the case on the vast majority of commercial projects — the client must appoint a principal designer and a principal contractor in writing before the pre-construction phase begins. The principal designer manages health and safety during the design and pre-construction phase, whilst the principal contractor manages it during construction.
Key point: If you fail to appoint a principal designer, the designer in control of the pre-construction phase automatically takes on that role. If you fail to appoint a principal contractor, the contractor in control of the construction phase takes on that role. In both cases, the client retains liability for any duties those appointees fail to fulfil.
Notifiable Projects — When to Submit an F10
A project is notifiable to the HSE if the construction phase will last longer than 30 working days with more than 20 workers simultaneously, or if it will exceed 500 person-days of construction work. The client must ensure the HSE is notified before the construction phase begins using the F10 notification form, available on the HSE website. The notification must be displayed at the construction site.
The Construction Phase Plan and Health and Safety File
The principal contractor must prepare a construction phase plan before work begins. This document sets out the arrangements for managing health and safety during construction. At the end of the project, the principal designer (or principal contractor if there is no principal designer) must prepare a health and safety file containing information needed for future maintenance, repair, or demolition. The client must keep this file and make it available to anyone who needs it.
Client Duties in Summary
- Make suitable arrangements for managing the project, including allocating sufficient time and resources
- Ensure that those appointed are competent and have the resources to fulfil their duties
- Ensure the pre-construction information is compiled and provided to designers and contractors
- Appoint a principal designer and principal contractor (for projects with more than one contractor)
- Ensure the construction phase does not start until a construction phase plan is in place
- Ensure the principal designer prepares a health and safety file
- Notify the HSE for notifiable projects
How Cinis Group Can Help
Our CDM consultants can act as your principal designer, conduct CDM audits to verify compliance at any stage of a project, and provide task-specific risk assessments and method statements (RAMS). Contact us to discuss how we can support your next construction project.
Editorial notice: This article is provided for general informational purposes only and does not constitute professional legal, regulatory, or health and safety advice. Whilst every effort has been made to ensure accuracy at the time of publication, laws and enforcement guidance change frequently — always verify information against current official sources such as hse.gov.uk. Any third-party names, organisations, or trademarks referenced in this article (including but not limited to the Health and Safety Executive (HSE), Network Rail, AB Agri, NEBOSH, IOSH, and IFSM) are the property of their respective owners and are referenced solely for informational purposes. Such references do not imply any affiliation with, sponsorship by, or endorsement from those organisations. © 2026 Cinis Group Ltd. All rights reserved. Reproduction of this article without prior written consent is prohibited.