The client
The client is the person or organisation for whom the construction work is carried out. On commercial projects, this is usually the developer, building owner, or occupier commissioning the work. On domestic projects, the homeowner is the client.
The client has overarching duties that cannot be delegated to other duty holders. These include making suitable arrangements for managing the project (including allocating sufficient time and resources), ensuring that relevant information is provided to designers and contractors before work begins, ensuring that a construction phase plan is in place before work starts, and ensuring that a health and safety file is prepared for the completed structure.
The client must also ensure that the principal designer and principal contractor carry out their duties. This does not mean the client must supervise their work day-to-day, but the client must take reasonable steps to satisfy themselves that the appointees are competent and performing their roles.
The principal designer
The principal designer must be appointed on any project with more than one contractor. They must be a designer (an organisation or individual that prepares or modifies designs) and must have the skills, knowledge, experience, and organisational capability to fulfil the role.
The principal designer's duties focus on the pre-construction phase: planning, managing, and monitoring the pre-construction phase, coordinating health and safety matters during design, ensuring designers comply with their CDM duties, assisting the client in providing pre-construction information, and preparing and updating the health and safety file.
In practice, the principal designer should be the design team leader. On most projects, this is the lead architect or consulting engineer. The appointment should be made as early as possible — ideally at RIBA Stage 1 (Preparation and Briefing) — so that health and safety is embedded in the design from the start.
The principal contractor
The principal contractor must be appointed on any project with more than one contractor. They must be a contractor and must have the skills, knowledge, experience, and organisational capability to fulfil the role.
The principal contractor's duties focus on the construction phase: planning, managing, and monitoring the construction phase, coordinating the work of all contractors, drawing up the construction phase plan, organising cooperation between contractors, ensuring every contractor and worker receives a suitable site induction, ensuring the site is secured, and consulting and engaging with workers on health and safety matters.
On most projects, the main contractor (or managing contractor) is appointed as principal contractor. The appointment should be made early enough to allow the construction phase plan to be prepared before work begins.
Designers
Every designer on a construction project has duties under CDM 2015. A designer is anyone who prepares or modifies a design (including drawings, design details, specifications, and bills of quantities) relating to a structure, or who arranges for or instructs someone under their control to do so.
Designers must not commence work unless satisfied that the client is aware of their CDM duties. When preparing or modifying designs, designers must eliminate foreseeable risks to health and safety so far as is reasonably practicable, reduce risks that cannot be eliminated, and provide information about remaining risks to other duty holders. This hierarchy (eliminate, reduce, inform) is the core design duty.
Contractors
Every contractor (including specialist subcontractors) has duties under CDM 2015. Contractors must not carry out construction work unless satisfied that the client is aware of their CDM duties and that there is a construction phase plan in place for the project.
Contractors must plan, manage, and monitor their own work and that of any workers under their control, ensure that any part of the design they prepare complies with designer duties, provide information and instruction to their workers, comply with the principal contractor's directions and site rules, and cooperate with the principal contractor and other contractors.
The appointment chain
Appointments must be in writing. The client appoints the principal designer and the principal contractor. The principal contractor may appoint subcontractors. Each appointment should confirm the scope of the role, the competence of the appointee, and the resources available.
If the client fails to appoint a principal designer or principal contractor when required, the client assumes those duties by default. This is rarely a good outcome — clients are typically not equipped to coordinate health and safety during design or manage the construction phase.