CDM 2015
Duty Holder Guide

Principal Designer

cdm 2015 Principal Designer

CDM 2015 defines the principal designer as the designer with control over the pre-construction phase of the project. There can only be one principal designer and they must be appointed on all projects with more than one contractor.

Principal designers have important duties under CDM, and must also assist with client duties. In this guide, we will take you through your responsibilities step-by-step. We will also link you to tools, resources and checklists to help you carry out your role.


The principal designer is an organisation (or on a smaller project they may be an individual) that has a technical knowledge of the construction industry relevant to the project, and the understanding and skills to manage and coordinate the pre-construction phase, including any design work carried out after construction begins.

Any project with more than one contractor at any time (including subcontractors) needs a principal designer, so this role is required on most construction projects. Any project with a principal contractor also needs a principal designer. The principal designer is appointed by the client, usually in writing, but appointment can also happen automatically on domestic projects.

It is important for the principal designer to establish and maintain good relationships with the client, principal contractor and other designers on the project.

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Pre-Construction Phase
Before Construction Starts

The pre-construction phase is all the work that happens on a project before any work starts on site. This is the very earliest stage of a project and may also be referred to as the planning phase of the project. It's when designers and contractors are selected, and you plan and prepare for the project.

Project set up assistance

One of the important duties of the principal designer is to assist the client in the project set up and in understanding their duties. This will include help in gathering the project information, assisting coordination between the project team and in the production of the pre construction information.

If the client is unfamiliar with construction projects, one of the first things you must do is make them aware of their client duties under CDM.

Establish what type of client you're working with, and remember that some client duties may transfer to you or the principal contractor if you are working with a domestic client.

You should help the client prepare their client brief. This will help outline the clients requirements and share expectations with the rest of the project team, so these requirements can be taken into account when planning the project.

Where the project is notifiable, check that the client has completed and submitted an F10 notification (or they may request you submit the notification on their behalf). Use our free CDM notification calculator to check if the project needs to be notified.

Coordinate the pre-construction phase

The main focus of the principal designer role is to plan, manage and monitor the coordination of the pre-construction phase, including any preparatory work carried out for the project.

This includes not only the preparation of the pre-construction information, but also in coordination with the project team, particularly the client and designers, and overseeing design decisions.

During the pre-construction phase, the principal designer has a responsibility to coordinate health and safety with all designers on the project. You should provide relevant information to designers as it becomes available, and make sure that risks are considered between the different designers, particularly where they may impact each other.

Decisions about the design taken during the pre-construction phase can have a significant effect on health and safety, both during construction and future use. The principal designer has an important role in influencing how risks should be managed.

Design meetings are a good way to bring designers together to:

  1. Ensure everyone carried out their CDM duties
  2. Consider information required for the pre-construction information
  3. Discuss the risks that should be addressed during the pre-construction phase
  4. Decide on the control measures to be adopted
  5. Agree the information that will help prepare the construction phase plan

You should focus your attention on areas with high or unusual risks to health and safety.

Regular meetings with the client throughout the pre-construction phase will provide you with an opportunity to update the client on the development of the pre-construction information, and to raise any potential issues.

If you appoint any designers, as the principal designer you must check they have sufficient skills, knowledge experience and capability to carry out the work. You should also advise the client on this requirement and assist the client in checking this for any designers they appoint. Checks should be carried out before appointment.

Assist compiling the pre-construction information

The client is required to identify and obtain pre-construction information. You should assist the client in doing this where necessary, and this information should be reviewed to identify any potential impacts on health and safety. Where you identify any shortfalls in the information, you will need to advise the client on how to address them.

You should:

  1. Check the adequacy of existing information
  2. Identify any gaps in existing information
  3. Advise the client how any gaps can be filled
  4. Help the client gather any necessary additional information

The principal designer collates the information for passing initially to the designers and then to the principal contractor for the construction phase. Updates may need to be provided, as information becomes available and surveys are carried out to fill any gaps.

You should provide the pre-construction, including updates and additional information as it becomes available, promptly and in a convenient form to contractors and designers that have been appointed or are being considered for appointment.

Identify, eliminate and control foreseeable risks

The principal designer should identify, eliminate, reduce and control risks in their own design, and the overall project design.

Designers must provide health and safety information relating to their design.

When designs are provided, undertake a review of health and safety information provided from designers. Consider any remaining risks, sequencing requirements, assumptions and key decisions. Any unusual risks need to be should be clearly identified and communicated.

Identification of risks is not enough to comply with CDM. You must demonstrate how the significant risks likely to arise during construction, maintenance or use of the building have been addressed.

Principal designers should follow the general principals of prevention, and ensure the design team:

  1. Eliminates the risks where possible
  2. Reduces any remaining risks
  3. Controls risks to an acceptable level

This information is an important part of the pre-construction information that will be provided to the principal contractor.

Ensure designers comply

The principal designer must ensure that the designers comply with their duties during the design stage. This involves finding out how they will consider health and safety and how they will review its effectiveness, focusing attention on areas where there is a high risk to health and safety.

Talk to designers early to find out how they will comply with CDM and consider health and safety during the project lifecycle, including risks at construction, maintenance and use stages. Make it clear what you expect from designers, including how you expect them to work together.

You must ensure that everyone working on the pre-construction phase cooperates with each other. Effective communication should be established and information shared within the project team.

Appropriate checks should be made by you as the principal designer to ensure designers are dealing with design risks as required. These checks should be incorporated into the design process.

Any design risks that cannot be eliminated should be included in information provided from designers, particularly unusual or complex risks that may be missed or misunderstood by others on the project.

Designers should provide regular updates, including information about issues or design changes that could potentially impact on health and safety.

The principal designer should encourage designers to regularly talk and listen to each other throughout the design period.

Advise on time and resources

Clients have a duty to allocate sufficient time and other resources. The principal designer must assist with estimating the period of time required to complete the work or work stages during the pre-construction phase.

You must communicate decisions taken about design, technical and organisational issues during the pre-construction phase, to plan which items or stages can take place at the same time or in a particular sequence, and estimations of the time needed to complete certain items or stages of work.

This information can be included within the pre-construction information and distributed to the project team.

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Construction Phase
When Work Starts On Site

The construction phase is when work that has been planned begins on site. It's when the site gets set up and the construction work could include demolition, maintenance and/or building activities.

Liaise during the construction phase

The principal designer should liaise with the principal contractor and other designers throughout the construction phase, and be able to answer any questions or queries regarding the pre-construction information or design information.

Communication during the construction phase should also focus on any ongoing design work. For example, the discovery of an underground obstruction not previously identified during site investigations might impact the structural design and choice or layout of foundations.

There may be an issue or change that could potentially impact on health and safety during maintenance, operation and demolition, so it is important that communication remains effective throughout the duration of your appointment.

It is a duty of the principal designer to assist the principal contractor in the preparation of the construction phase plan by providing all relevant information (pre-construction information). It is good practice to check the construction phase plan has been produced and that there is no information missing.

Prepare the health and safety file

The principal designer is responsible for preparing the health and safety file and the principal contractor should pass on to them any relevant health and safety information required.

The health and safety file must contain relevant information that should be taken into account for future work on the building after the project has finished.

You should prepare the file, update and revise it as the project progresses.

Requirements for the health and safety file, including its structure, content and format, should be identified before the construction phase and communicated by the principal designer.

The file contains the information needed to ensure the health and safety of anyone carrying out any future construction, demolition, use, cleaning or maintenance work on the building or structure.

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Post-Construction Phase
Project Completion

The post-construction phase is what happens at the end of the project. This may also be referred to as the handover phase of the project. It's when the construction work finishes and the project is signed-off and handed over the client.

Review, update and revise the health and safety file

Early collection of health and safety file information by the principal designer will help to ensure all the required information is obtained.

As information becomes available the health and safety file should be updated ready for handover on project completion.

You may need to continue liaising with the principal contractor to gather the necessary handover information to finalise the health and safety file. It is a good idea to set a timeframe for the collection of information for the health and safety file at the start of the project to ensure the health and safety file can be handed over the client in a timely manner.

Handover the health and safety file

The principal designer should ensure that the health and safety file is handed over to the client. However, if your appointment ends before the project is completed, you must hand over the file to the principal contractor.

If your appointment finishes before the end of the project you must ensure the principal contractor:

  1. Is aware of the risks that have not been eliminated by designers
  2. Understand the ways those risks have been reduced or controlled
  3. Understands the implications for implementing any further design work
  4. Is aware of any issues to take into account when reviewing, updating and completing the health and safety file

Make sure you provide the principal contractor with details of any agreed format, structure and required content for the health and safety file.

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