CDM Duty Holders Explained: Roles and Responsibilities Under CDM 2015

The single most common cause of CDM failures is not bad intent — it is confusion over who is responsible for what. The client thinks the principal designer is handling something; the principal designer thinks it is the principal contractor's job; the contractor assumes the client signed it off. CDM 2015 assigns each duty to a named role, and once you can see the map, most of that confusion disappears.

This guide sets out the five duty holders under the Construction (Design and Management) Regulations 2015, what each is responsible for, when each role exists, and how the duties connect. It is the role-map that sits behind the three CDM documents — pre-construction information, the construction phase plan, and the health and safety file.

The five CDM duty holders

CDM 2015 defines five duty-holder roles. On any given project, one person or organisation may hold more than one role, and some roles only exist on multi-contractor projects:

The two "principal" roles — principal designer and principal contractor — only exist where there is, or it is reasonably foreseeable there will be, more than one contractor. On a true single-contractor project, the lone contractor picks up most of the principal contractor's duties directly.

Client duties

The client sits at the top of the chain, and CDM 2015 deliberately gives the client real, non-delegable duties — because the client controls the budget, the programme and the appointments that determine whether a project can be run safely. Regulation 4 ("Client duties in relation to managing projects") sets these out. A client must:

• make suitable arrangements for managing the project so that health and safety is secured, and maintain and review those arrangements;
• ensure the principal designer and principal contractor are appointed where there is more than one contractor (Regulation 5) — and if the client fails to appoint them, the client takes on their duties by default;
• provide pre-construction information to every designer and contractor, as soon as is practicable (Regulation 4(4) — see our pre-construction information guide);
• ensure a construction phase plan is drawn up before the construction phase begins;
• ensure the health and safety file is prepared and kept available for inspection (Regulation 4(5)(b)), and passed on if the structure changes hands (Regulation 4(7)).

For domestic clients — individuals having work done on their own home, not in connection with a business — CDM 2015 transfers most of these duties automatically to the contractor (single-contractor projects) or principal contractor (multi-contractor projects), so a homeowner does not have to act as a CDM client.

Principal designer role

The principal designer plans, manages and monitors the pre-construction phase. The role is performed by a designer (an organisation or individual with the right design experience) appointed by the client. Regulation 11 ("Duties of a principal designer in relation to health and safety at the pre-construction phase") sets the duties. The principal designer must:

• plan, manage and monitor the pre-construction phase, coordinating health and safety so far as is reasonably practicable;
• help the client collate and issue the pre-construction information to designers and contractors;
• ensure designers comply with their duties and cooperate with one another;
• prepare the health and safety file (Regulation 12(5)) and pass it on if the appointment ends before the project does (Regulation 12(8)).

A common confusion: the principal designer is a CDM role, not necessarily the lead architect. It is whoever the client appoints to control health and safety during design — though in practice it is often the lead design organisation.

Designer duties

A designer is anyone who prepares or modifies a design, or arranges for or instructs someone to do so — architects, engineers, and in some cases contractors making design decisions on site. Regulation 9 ("Duties of designers") requires designers to:

• eliminate, so far as is reasonably practicable, foreseeable health and safety risks in the design;
• where risks cannot be eliminated, reduce or control them through design, and provide information about remaining risks;
• ensure the client is aware of their own duties before starting design work.

The principle is "design out the risk": the cheapest and safest place to remove a hazard is on the drawing board, before it is built in.

Principal contractor duties

The principal contractor plans, manages and monitors the construction phase — the on-site mirror of the principal designer's pre-construction role. Regulation 13 ("Duties of a principal contractor in relation to health and safety at the construction phase") and Regulation 12 set the duties. The principal contractor must:

• plan, manage and monitor the construction phase, coordinating health and safety on site;
• draw up the construction phase plan before setting up the site (Regulation 12(1) — see our construction phase plan guide);
• organise cooperation between contractors and the sharing of information;
• ensure site inductions, control site access, and provide welfare facilities;
• provide the principal designer with information for the health and safety file (Regulation 12(7)).

For the full detail of this role, see our dedicated guide to CDM principal contractor duties.

Contractor duties

A contractor is anyone who carries out, manages or controls construction work. Regulation 15 ("Duties of contractors") requires every contractor to:

• plan, manage and monitor their own work so it is carried out safely;
• comply with directions from the principal designer or principal contractor;
• not start work until satisfied that reasonable steps have been taken to prevent access by unauthorised persons;
• provide their workers with the necessary information, instruction, training and supervision.

On a single-contractor project, where there is no principal contractor, the contractor takes on the additional duty of drawing up the construction phase plan (Regulation 15(5)).

How the roles connect

The roles are designed to hand off to each other across the life of the project:

1. The client appoints the duty holders and provides pre-construction information.
2. The principal designer and designers plan and design the work safely, and start the health and safety file.
3. The principal contractor and contractors build the work safely under the construction phase plan.
4. The health and safety file completes and returns to the client, ready to become pre-construction information for the next project.

That is the whole of CDM 2015 in one sentence: the right information, prepared by the right duty holder, at the right point in the project. For the broader regulatory picture, see our complete CDM compliance guide.

Bottom line

There are five CDM duty holders — client, principal designer, designer, principal contractor, contractor. The two "principal" roles exist only on multi-contractor projects. Each duty in CDM 2015 belongs to a named role, and most CDM failures come from those roles being unclear. Map the roles to your project, appoint in writing under Regulation 5, and the documents — pre-construction information, construction phase plan, health and safety file — fall into place.

To produce two of those documents from a starting structure, download our free CDM document pack template.

Sources

• CDM 2015 Regulation 4 — client duties
• CDM 2015 Regulation 9 — duties of designers
• CDM 2015 Regulation 11 — duties of the principal designer (pre-construction phase)
• CDM 2015 Regulation 13 — duties of the principal contractor (construction phase)
• CDM 2015 Regulation 15 — duties of contractors
• HSE — Managing health and safety in construction (L153)

This guide is for informational purposes and does not constitute legal advice. For project-specific CDM duties, consult your CDM advisor or principal designer. Last reviewed against CDM 2015 (SI 2015/51) on 2026-06-04.