Principal designer

What are the CDM principal designer's duties?

Short answer

Regulation 11 of CDM 2015 requires the principal designer to plan, manage and monitor the pre-construction phase and coordinate health and safety through it; to identify, eliminate or control foreseeable risks; to ensure every designer complies with their own duties; to help the client provide the pre-construction information and get it to the designers and contractors who need it; and to liaise with the principal contractor. Regulation 12(5) adds preparing the health and safety file.

The duties, one by one

  1. Plan, manage and monitor the pre-construction phase

    Regulation 11(1). Coordinate health and safety through it so the project can be carried out without risks to health or safety so far as is reasonably practicable. On a small project this is mostly about sequence and information rather than meetings.

  2. Take account of the general principles of prevention

    Regulation 11(2), when decisions are being taken about design, technical and organisational aspects, and when estimating how long the work will take. Time is a safety decision as much as a programme one.

  3. Identify, eliminate or control foreseeable risks

    Regulation 11(3), for anyone building, anyone maintaining or cleaning the structure afterwards, and anyone who will use it as a workplace.

  4. Ensure designers comply

    Regulation 11(4). Not merely hope they have. This is why a principal designer has to ask each designer what their design leaves behind, and record the answer.

  5. Ensure cooperation

    Regulation 11(5). Everyone working on the pre-construction phase cooperates with the client, the principal designer and each other.

  6. Assist with, and issue, the pre-construction information

    Regulation 11(6). Help the client bring it together and provide it promptly and in a convenient form to every designer and contractor.

  7. Liaise with the principal contractor

    Regulation 11(7), for the duration of the appointment, sharing anything relevant to planning, managing and monitoring the construction phase.

  8. Prepare the health and safety file

    Regulation 12(5), appropriate to the characteristics of the project, keeping it reviewed and updated, and passing it to the client at the end or to the principal contractor if the appointment finishes first.

What is not a principal designer duty

How long the duties last

The pre-construction phase is not over when the builder arrives. It runs for as long as design work continues, which on most projects means well into construction: structural details, contractor designed elements, substitutions, and changes the client instructs. That is why most appointments sensibly run through to completion. More on timing.

Written by Robbie Thompson, BA (Hons) Dip Arch, SMSTSLast reviewed 28 August 2026How we write this

Sources

  1. CDM 2015, regulation 11: duties of a principal designer legislation.gov.uk
  2. CDM 2015, regulation 12: construction phase plan and health and safety file legislation.gov.uk
  3. CDM 2015, regulation 7: application to domestic clients legislation.gov.uk
  4. HSE: principal designers, roles and responsibilities hse.gov.uk
  5. Managing health and safety in construction, L153 HSE guidance on the Regulations

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