CDM Regulations 2015 – What Principal Designers Need to Know!

The CDM Regulations 2015 came into force on 6th April 2015 and replaced the CDM Regulations 2007; these being the main set of regulations for managing the health, safety and welfare on construction projects.

The CDM Regulations apply to all building and construction work and includes new build, demolition, refurbishment, extensions, conversions, repair and maintenance. The CDM Regulations place responsibility for managing health and safety of a construction project on three main duty holders, these being the Client, the Principal Designer and the Principal Contractor.

The overall aim of the regulations is to make health and safety an essential and integral part of the planning and management of projects, so as to reduce the health and safety risks of those who work on the structure, those who will use it as a work place, or others who work on the structure once it’s complete.


A Principal Designer is the Designer with control over the pre-construction phase of the project. This is the very earliest stage of a project from concept design through to planning the delivery of the construction work. The Principal Designer must be appointed in writing by the Client.

The Principal Designer can be an organisation or an individual that has the technical knowledge of the construction industry relevant to the project and the skills, knowledge and experience to understand, manage and coordinate the pre-construction phase, including any design work carried out after construction begins.  The Principal Designer may also have separate duties as Designers.

In liaison with the Client and Principal Contractor, the Principal Designer has an important role in influencing how the risks to health and safety should be managed and incorporated into the wider management of a project. Decisions about the design taken during the pre-construction phase can have a significant effect on whether the project is delivered in a way that secures health and safety. The Principal Designer’s role involves coordinating the work of others in the project team. The extent of these duties will be dependent upon the type, nature and complexity of the project.  On some projects you may need CDM Advisor/Consultant to help you comply with these duties.

Regardless of the size or duration of your project, the CDM Regulations separates construction projects into two, projects with only one contractor or projects that are likely to involve more than one contractor (this will be the majority of projects).   If you are in doubt, you should assume that the project will require more than one contractor.


Planning, managing, monitoring and coordinating the pre-construction phase

In carrying out the duty to plan, manage, monitor and coordinate the pre-construction phase, Principal Designers must take account of the general principles of prevention and, where relevant, the content of the Pre-Construction Information, any Construction Phase Plan and any existing Health and Safety File.  This information should be taken into account particularly when decisions are being taken about design, technical and organisational issues to plan which items or stages of work can take place at the same time or in what sequence; and when estimating the time needed to complete certain items or stages of work.

The Principal Designer’s work should focus on ensuring the design work in the pre-construction phase contributes to the delivery of positive health and safety outcomes. Bringing together Designers as early as possible in the project, and then on a regular basis, to ensure everyone carries out their duties, will help to achieve this.

If the Principal Designer appoints a Designer, they must check they have sufficient skills, knowledge, experience and (if they are an organisation) the organisational capability to carry out the work.

Identifying, eliminating or controlling foreseeable risks

Principal Designers must ensure, as far as is reasonably practicable, that foreseeable risks to health and safety are identified. The risks that should be identified are the significant ones, which are likely to arise during construction work, or during maintenance, cleaning or using the building as a workplace.

Identifying insignificant risks is not an effective way of alerting other duty holders to the important design issues they need to know about. Designers should be able to demonstrate they have addressed only the significant risks. Once the risks have been identified, Principal Designers must follow the approach to managing them set out in the general principles of prevention.  The Principal Designer must, as far as reasonably practicable, ensure that the design team: (a) eliminate the risks associated with design elements (b) reduce any remaining risks; or (c) control them.

Ensuring coordination and cooperation

Principal Designers must ensure as far as reasonably practicable that everyone involved in working on the pre-construction phase cooperates with each other, that Designers comply with their duties (appropriate checks should be made to ensure Designers are dealing with design risks appropriately) and that Designers provide information about elements of the design which present significant risks that cannot be eliminated. This should include information about unusual or complex risks that are more likely to be missed or misunderstood by contractors or others on the project.

Providing pre-construction information

Pre-construction information is information already in the Client’s possession or which is reasonably obtainable. It must be relevant, have an appropriate level of detail and be proportionate to the nature of risks involved in the project. The Principal Designer must help the Client bring together the information the Client already holds. The Principal Designer should then assess the adequacy of existing information to identify any gaps in the information and advise the Client on how the gaps can be filled and help them in gathering the necessary additional information.  This additional information should be issued in a convenient form to help Designers and Contractors who are being considered for appointment, or have already been appointed, to carry out their duties.

Liaising with the Principal Contractor

The Principal Designer must liaise with the Principal Contractor for the duration of their appointment. During the pre-construction phase this must cover sharing information that may affect the planning, management, monitoring and coordination of the construction phase – in particular, the information needed by the Principal Contractor to prepare the construction phase plan. Liaison should also extend into the construction phase to deal with ongoing design and obtaining information for the health and safety file.

If the Principal Designer’s appointment finishes before the end of the project, they must ensure that the Principal Contractor has all the relevant information so that the Principal Contractor is aware of the risks which have not been eliminated in the designs.

The Health and Safety File

The health and safety file is only required for projects involving more than one contractor. It must contain relevant information about the project which should be taken into account when any construction work is carried out on the building after the current project has finished. Information included should only be that which is needed to plan and carry out future work safely and without risks to health.

The Principal Designer must prepare the file, and review, update and revise it as the project progresses. If their appointment continues to the end of the project they must also pass the completed file to the Client to keep. If the Principal Designer’s appointment finishes before the end of the project, the file must be passed to the Principal Contractor. The Principal Contractor must then take responsibility for reviewing, updating and revising it and passing it on to the Client.

The Principal Designer

The Principal Designer role is purely a health and safety co-ordination role required during the Pre-Construction Phase of a project.  As a Principal Designer, you have specific health and safety responsibilities, however, Marpal, as CDM Consultants can help to ease the burden.

For further information on CDM or the role of the Principal Designer, please contact Paul Littlewood by phone (01332 668877) or email ([email protected]).

Marpal - CDM Consultancy - Long CTA

CDM Regulations 2015: Client Information Sheet

CDM Regulations 2015: Client Information Sheet


CDM Regulations 2015: Principal Designer Information Sheet

CDM Regulations 2015: Principal Designer Information Sheet


CDM Regulations 2015: Principal Contractor Information Sheet

CDM Regulations 2015: Principal Contractor Information Sheet