A Complete Guide To The Construction (Design And Management) Regulations 2015 (CDM 2015)

Post Updated 24th June 2025

The Construction (Design and Management) Regulations, more commonly known as CDM, were introduced in 1994 to improve health and safety across construction projects in the UK. Updated most recently in April 2015, the CDM Regulations 2015 set out clear legal duties for everyone involved in construction work, from clients and designers to contractors.

The aim of CDM 2015 is to ensure that health and safety is considered and managed throughout the lifecycle of a construction project, from the initial design stage to project completion and ongoing maintenance.

In this guide, we explain the CDM Regulations, who they apply to, and what each dutyholder must do to ensure compliance and reduce risk. Find out more about how Veriforce CHAS helps contractors and clients comply with CDM.

What Is The CDM 2015 And Why Are The Regulations Important?

Construction is one of the most dangerous industries. Statistics show that almost 70 thousand construction workers suffered from work-related ill health from 2020 to 2023. The fatal injury rate for the construction industry is also four times higher than the all-industry rate.

The CDM regulations aim to improve health and safety across all stages of a project’s development to minimise risk to workers and site visitors.

Complying with CDM 2015 Regulations is a legal requirement. By adhering to the regulations, clients and contractors can ensure that projects are carried out according to health and safety best practices, from managing risks in the pre-construction phase to coordinating with employees and subcontractors during the build process and compiling and handing over the health and safety file upon project completion to facilitate alterations, ongoing maintenance or demolition once the project is complete.

A Summary Of The CDM Regulations

The Construction (Design and Management) Regulations outline the health and safety responsibilities of various “dutyholders”.

These dutyholders reflect the key roles involved throughout the construction process. The CDM 2015 Regulations dutyholders are:

• Client
• Principal designer
• Principal contractor
• Designer
• Contractor.

Projects do not require individuals to fulfil all roles. For example, the CDM 2015 Regulations only requires a principal designer to be appointed when more than one contractor works on a project at a time. A person may also hold multiple roles.

For example, if the client fails to appoint a principal designer and/or principal contractor on a project with more than one contractor, then the duties of these dutyholders must be fulfilled by the client.

The CDM Regulations 2015 include an overview of the various terms used throughout the legislation — including definitions for each dutyholder, the construction phase plan and construction work — the health and safety duties of each role and general requirements for all construction sites.

CDM Regulations Summary

• Part 1: Introduction
• Part 2: Client duties (including arrangements for managing a project and appointing relevant dutyholders such as principal designers and principal contractors.)
• Part 3: Health and safety duties and roles (general duties and the responsibilities of designers, principal designers, contractors and principal contractors.)
• Part 4: General requirements for all construction sites (including requirements relating to safe access and egress, site security, emergency procedures, fire detection and fire-fighting, prevention of drowning and and the requirement to provide sufficient working space.)
• Part 5: General (this section revokes the 2007 CDM Regulations and establishes the requirement for the Secretary of State to review the regulations periodically.)

Client Responsibilities

Client responsibilities include ensuring the project is safely planned, resourced, and delivered in compliance with health and safety law.

The CDM regulations define a client as any person for whom a construction project is carried out. Clients can be either domestic or commercial, depending on whether the construction project is being carried out in connection with a business.

Part 2 of the CDM regulations outlines the client duties in relation to managing construction projects:

• Appointing a principal designer and principal contractor if more than one contractor is working (or expected to work) on a project. The client must appoint these roles in writing; otherwise, they are legally responsible for carrying out these duties.
• Providing pre-construction information to every designer and contractor appointed to communicate expected standards and project requirements. Pre-construction information is any information relevant to the construction work, including:
  • The reason for the construction work
  • The work involved and vision for the completed project
  • How the project will be planned and managed
  • Health and safety hazards and how they will be addressed
  • The extent and location of existing information such as that included in the health & safety file, including existing services, structures and ground conditions.
• Allocating sufficient time and resources to complete the project without risks (so far as is reasonably practicable) to the health or safety of any person involved.
• Ensuring the principal contractor (or sole contractor if a principal contractor is not appointed) draws up a construction phase plan before construction begins.
• Ensuring the principal designer prepares a health and safety file for the project.
• Notifying the Health and Safety Executive if construction work is scheduled to exceed 500 person days or last longer than 30 working days, and involve more than 20 people working simultaneously on the project.
• Notifying the Office for Nuclear Regulation instead of the Executive if the project includes construction work on premises on a GB nuclear site, a new nuclear build site or an authorised defence site.
• Notifying the Office of Rail and Road Regulation instead of the Executive where the project includes work for which the Office of Rail  and Road Regulation is the enforcing authority by virtue of regulation 3 of the Health and Safety (Enforcing Authority for Railways and Other Guided Transport Systems) Regulations 2006.

Domestic Clients

Domestic clients having work done on their home or private property will pass these responsibilities (except notifying the Office for Nuclear Regulation, which does not apply) to either:

• The sole contractor
• The principal contractor (where there is more than one contractor on the project)
• The principal designer, where a written agreement states they will fulfil those duties).

When a domestic client fails to appoint a principal designer or contractor, the individuals controlling the pre-construction and construction phases, respectively, hold principal roles.

Principal Designer Responsibilities

Principal designers are responsible for planning and managing health and safety during pre-construction.

One of the notable changes made to the CDM regs in 2015 was the introduction of the “principal designer”, replacing the “CDM coordinator” role.

The CDM coordinator’s responsibility was to advise and support the project team to ensure CDM compliance.

Many responsibilities carry over to the principal designer role, with others transferred to the principal contractor. The updated regulations make these roles more analogous to one another: where the principal contractor oversees the construction phase of the project, and the principal designer is responsible for CDM compliance before construction begins.

Any designer appointed to a project must have the skills, knowledge, and experience necessary to fulfil the role safely, but the principal designer role carries additional responsibilities.

These duties include:

• Preparing a health and safety file for the project and revising it as appropriate.
• Planning, managing and monitoring the pre-construction phase to minimise risks to health and safety. This requirement includes providing pre-construction information to the client and every designer and contractor appointed (or being considered for appointment) to the project.
• Estimating the time required to complete the various stages of work scheduled to take place.
• Identifying and eliminating foreseeable risks to the health and safety of any person carrying out construction work, maintaining or cleaning structures and using structures designed as a workplace. Control measures should be implemented to reduce any remaining risks and improve the health and safety of the building site and the  overall project.
• Ensuring all designers carry out their CDM duties.
• Assisting the client in the provision of pre-construction information and providing it to each designer and contractor appointed on the project.
• Liaising with the principal contractor during their appointment, including sharing information related to the planning, management and monitoring of the construction phase.

Principal Contractor Responsibilities

Principal contractors are responsible for managing health and safety during the project’s construction phase.

While the principal designer takes charge of the pre-construction phase of the project, the principal contractor takes the lead during the construction phase.

Clients should appoint this role to a contractor with the necessary skills, experience and training to manage the construction while ensuring health and safety standards are met. The principal contractor has the same responsibilities as any other contractor, plus several more specific to the role:

• Draw up a construction phase plan and review and update it so that construction work is carried out with consideration of risks to health and safety. 
• Plan, manage and monitor the construction phase to ensure that construction work is carried out without risks to health or safety, in line with the principles of prevention.
• Consider all health and safety risks that could arise during the construction phase.
• Manage and supervise contractors, ensuring the right contractors are hired (including that they possess the appropriate skills, knowledge, training and experience), conducting a suitable site induction, organising work schedules, providing project site information and informing contractors of hazards, risks and control measures. The principal contractor is responsible for cooperating with workers in developing, promoting and checking the effectiveness of measures designed to ensure their health, safety and welfare.
• Take necessary steps to prevent access to the construction site by unauthorised persons.
• Provide welfare and sanitary facilities such as toilets, washing facilities, drinking water, changing rooms and rest stations before work begins.
• Liaise with the principal designer to review pre-construction information, coordinate health and safety matters and determine the design and methods that will be used to achieve the desired project results. This communication is vital because it helps all parties understand how risks will be managed throughout the project.

The principal contractor may also be responsible for updating the health and safety file and passing it to the client upon project completion if there is no principal designer or the principal designer’s appointment concludes before the end of the project.

Designer Responsibilities

Designers are responsible for creating safe designs that eliminate or reduce risks during construction, use, and maintenance.

Designers are any individuals or organisations that provide or alter designs for a project. They might be architects, engineers, interior designers or surveyors. Their responsibilities include:

• Ensuring the client knows their responsibilities: A designer must not begin work unless they are satisfied the client is aware of the duties they owe to the designer, including appointing relevant roles and ensuring construction phase plans and health and safety files are prepared.
• Considering pre-construction information: When preparing or modifying designs, designers must take pre-construction information into account to eliminate foreseeable risks, which may impact design decisions. If it is not possible to eliminate such risks, the designer must take steps to reduce or control the risks, inform the principal designer and ensure the information is included in the health and safety file.
• Provide information about the design, construction or maintenance of the structure: Designers must take all reasonable steps to provide sufficient detail alongside the design to assist the client, other designers and contractors in complying with their duties as outlined in the CDM regulations.

Contractor Responsibilities

Contractors are responsible for carrying out construction work safely and in line with the construction phase plan.

Multiple contractors often work simultaneously on a project and must fulfil specific duties under the Construction (Design and Management) Regulations 2015.

• Ensure the client knows their responsibilities: Like designers, contractors must not commence work on a project before they are satisfied the client knows the duties owed under the regulations.
• Manage their work: Contractors must plan, manage and monitor the construction work they carry out to minimise risks to health and safety. Contractors must also provide appropriate supervision, instructions and information to each worker under their control.
• Comply with directions and the construction phase plan: Where there is more than one contractor assigned to a project, each contractor must comply with directions given by the principal designer or principal contractor and follow the parts of the construction phase plan relevant to their work.
• Prevent unauthorised access: Where the principal contractor must ensure necessary steps are taken to prevent unauthorised access to the construction site, it is the contractor’s responsibility not to begin work before this duty is fulfilled.

General Requirements For All Construction Sites

Part 4 of the CDM Regulations applies to construction sites and sets out the compliance requirements for creating safe and secure places of construction work. Included among these requirements are:

• A construction site must be kept safe for the health of any persons at work.
• Each part of a construction site must be kept in good order and in a reasonable state of cleanliness.
• A construction site must be fenced off or have a perimeter readily identified by signs.
• Timber or material with projecting nails or similarly sharp objects must not remain in any place or be used in construction work if they pose a danger to any person.
• Explosives must be stored, transported and used safely. A charge may be fired only if steps have been taken to prevent any risk of injury from the explosion or projected material.
• A construction site (including the traffic route to the site) must be sufficiently lit by natural light. Any artificial lighting should not adversely affect the perception of signs or signals, and secondary lighting must be provided where the failure of primary artificial lighting would endanger a worker’s health or safety.

Compliance with the CDM 2015 Regulations is mandatory in the United Kingdom. The CDM regulations apply to all construction projects, regardless of size and scope, and failure to comply can result in enforcement action by the HSE, as well as legal and financial penalties.

CHAS is here to help contractors comply with the CDM Regulations. CHAS members can access our discounted CDM training modules to help duty holders fulfil their duties, ensure compliance and effectively manage project risks

Become a CHAS contractor to gain access to low-cost training modules. Choose from our three accreditation packages: CHAS Standard (SSIP), CHAS Advanced (SSIP and PAS91) and CHAS Elite (Common Assessment Standard).

For clients, CHAS membership allows you to gain access to our pool of prequalified contractors, allowing you to reduce recruitment time and costs.