Construction & Property

Appoint a Principal Designer

Your duty as a construction client to appoint a Principal Designer when your project will involve more than one contractor. Covers who can be appointed, competence requirements, and what happens if you do not appoint.

UK-wide
Guide summary

If your construction project involves more than one contractor at any time, you must appoint a Principal Designer. They coordinate health and safety during the design phase. Appoint them in writing before construction starts, ideally before design work begins.

  • Appoint a Principal Designer if multiple contractors work on your project
  • Must be in writing before construction begins
  • Ideally appoint before design work starts
  • Principal Designer must be a competent designer
  • They coordinate health and safety in design
  • Check their skills and experience before appointing
  • Examples: architects, design firms, lead consultants
  • No need if only one contractor works on project
  • Late appointment reduces safety benefits
  • Keep written evidence of appointment
On this page
UK-wide

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If you are commissioning construction work that will involve more than one contractor at any time, you must appoint a Principal Designer under the Construction (Design and Management) Regulations 2015 (CDM 2015).

The Principal Designer coordinates health and safety during the pre-construction phase. They ensure that whoever designs the project considers how to eliminate or reduce risks to workers during construction, and to anyone who will later maintain, clean, or use the building.

Appointing the right person early makes your project safer and helps you meet your legal duties as a client.

When you must appoint a Principal Designer

You must appoint a Principal Designer if your project will have more than one contractor working on it at any time. This includes contractors working:

  • At the same time (overlapping)
  • One after another (sequentially)
  • On different parts of the project

It does not matter whether contractors are on site simultaneously. If two or more contractors will work on the project at any point, you need a Principal Designer.

Examples requiring Principal Designer appointment

  • An office fit-out using a main contractor plus separate M&E contractor
  • A house extension where one builder does groundwork and another does the build
  • A refurbishment with separate structural, electrical, and plumbing contractors
  • A development using a demolition contractor followed by a building contractor

When you do not need to appoint

If your project will use only one contractor throughout, you do not need to appoint a Principal Designer. However, you still have other CDM duties as a client.

When to make the appointment

You must appoint the Principal Designer:

  • As soon as practicable after recognising you need one
  • In any event before the construction phase begins

Ideally, appoint them before design work starts. The earlier they are involved, the more effectively they can coordinate health and safety into the design from the outset.

Late appointment undermines the purpose of CDM. If the Principal Designer joins after key design decisions are made, they cannot influence those decisions to reduce risk.

Minimum legal timing
Before construction phase begins
Recommended timing
Before design work starts
Appointment format
Must be in writing

Who can be Principal Designer

The Principal Designer must be:

  • A designer (someone who prepares or modifies designs for the project)
  • In control of the pre-construction phase (able to coordinate and direct design work)
  • Competent to fulfil the role (has the skills, knowledge, and experience needed)

This can be an organisation or an individual. Common appointees include:

Architects
Particularly those leading the design team with CDM experience
Multi-disciplinary design practices
Engineering consultancies, design and build contractors with in-house design capability
Lead consultants
Project managers or lead consultants with design oversight and CDM competence
Contractors with design capability
Design and build contractors who prepare designs as part of their scope

What the Principal Designer is not

The Principal Designer role is not the same as CDM Coordinator from the previous regulations. CDM Coordinators were abolished in 2015. The Principal Designer must be a designer with genuine control over design work, not a separate advisor.

A health and safety consultant who does not prepare designs cannot be a Principal Designer. However, they can support the Principal Designer with advice.

The CDM principal designer is also not the same as the Building Regulations principal designer. Since 1 October 2023, Part 2A of the Building Regulations 2010 (inserted by SI 2023/911) has created a separate statutory "principal designer" role for all building work in England that is subject to building regulations and involves more than one contractor. The competence criteria differ - the Building Regulations principal designer must be able to plan, manage and monitor the design work so the design complies with building regulations - and the appointment is legally separate. An England client with more than one contractor on building-regs work needs both appointments. The same firm can hold both roles, but each appointment must be made explicitly.

How to check competence

Before appointing someone as Principal Designer, you must take reasonable steps to satisfy yourself they have the skills, knowledge, training, and experience to fulfil the role.

The level of competence needed depends on the project's complexity and risks. A simple refurbishment needs less specialist expertise than a major demolition or high-rise development.

What to look for

  1. 1

    Relevant design experience

    They should have experience designing projects of similar type and complexity. Ask for examples of comparable projects where they acted as lead designer or Principal Designer.

  2. 2

    Understanding of CDM duties

    They must understand Principal Designer responsibilities under CDM 2015, particularly Regulations 11 and 12. Ask how they would fulfil these duties on your project.

  3. 3

    Health and safety knowledge

    They need knowledge of construction health and safety hazards and how design decisions can eliminate or reduce risks. Look for relevant qualifications or training.

  4. 4

    Coordination capability

    They must be able to coordinate other designers and communicate effectively with the client and Principal Contractor. Ask about their approach to coordination.

  5. 5

    Organisational capacity

    If appointing an organisation, check they have sufficient resources and systems to deliver the role effectively on your project.

Evidence of competence

You might ask for:

  • Examples of previous Principal Designer appointments
  • Relevant professional qualifications (ARB, RIBA, ICE, CIAT, etc.)
  • CDM or health and safety training certificates
  • Membership of professional bodies requiring CPD
  • References from previous clients
  • Case studies showing how they managed pre-construction health and safety

You do not need to conduct an elaborate assessment. The check should be proportionate to the project. For a major project, detailed due diligence is appropriate. For a straightforward project, confirming relevant experience and asking the right questions may be sufficient.

What the Principal Designer does

Once appointed, the Principal Designer has specific duties under Regulation 11 of CDM 2015:

Key responsibilities in practice

  1. 1

    Plan, manage and monitor the pre-construction phase

    Take control of health and safety planning before construction starts. Ensure designers have enough time and information to consider risks. Monitor progress and intervene if health and safety is being overlooked.

  2. 2

    Identify and manage design risks

    Work with designers to identify foreseeable risks from the design. Apply the hierarchy: eliminate risks where possible, reduce risks that cannot be eliminated, and communicate remaining risks to the Principal Contractor.

  3. 3

    Coordinate all designers

    Ensure different designers (architect, structural engineer, M&E consultants) communicate with each other about health and safety. Prevent gaps or contradictions in how risks are addressed.

  4. 4

    Help the client with pre-construction information

    Assist the client to gather and provide pre-construction information to designers and contractors. Make sure everyone has what they need to design and plan safely.

  5. 5

    Prepare the health and safety file

    Create and maintain a health and safety file containing information needed for future construction, maintenance, and demolition work. Pass it to the Principal Contractor during construction and to the client at project end.

  6. 6

    Liaise with the Principal Contractor

    Maintain contact with the Principal Contractor throughout your appointment. Share relevant information about design decisions, residual risks, and pre-construction planning that affects construction phase safety.

Making the appointment

The appointment must be in writing. This could be:

  • A specific letter of appointment
  • A clause in their professional services contract
  • An exchange of emails confirming the appointment

What to include

The written appointment should make clear:

  • That you are appointing them as Principal Designer under CDM 2015
  • That they accept the duties under Regulations 11 and 12
  • The project to which the appointment applies
  • When their appointment starts (and, if known, when it ends)

Keep a copy of the written appointment. HSE may ask for evidence of appointments during inspections or investigations.

For notifiable projects

If your project is notifiable (exceeds the thresholds for F10 notification), you must include the Principal Designer's contact details in your notification to HSE.

If you do not appoint a Principal Designer

If you fail to appoint a Principal Designer when your project requires one, you assume all Principal Designer duties yourself.

This means you, as the client, become responsible for:

  • Planning, managing, and monitoring the pre-construction phase
  • Identifying and managing design risks
  • Coordinating all designers
  • Preparing the health and safety file
  • Liaising with the Principal Contractor

For most commercial clients, this is not practical. These duties require design expertise and knowledge of construction health and safety that most clients do not have.

Failing to appoint does not remove the duties - it transfers them to you. You could face prosecution for breach of Principal Designer duties if you fail to fulfil them.

Domestic clients

If you are a domestic client (having work done on your own home for personal use, not as part of a business), different rules apply.

Domestic clients do not have to make CDM appointments themselves. Instead:

  • If no Principal Designer is appointed, the designer in control of the pre-construction phase automatically becomes the Principal Designer by default
  • Alternatively, a domestic client can enter a written agreement with the Principal Designer for them to take on client duties as well

Are you a domestic client?

You are a domestic client only if the work is on your own home for personal use. You are not a domestic client if you are:

  • A landlord commissioning work on rental property (this is a business activity)
  • A property developer building homes for sale (this is a business activity)
  • Having work done on commercial premises

If you commission work as part of any business, you are a commercial client with full appointment duties.

Penalties for non-compliance

Failing to appoint a Principal Designer when required is a breach of CDM 2015. It is also a breach if you appoint someone who is not competent.

Beyond criminal penalties, failure to appoint properly can result in:

  • Civil liability if accidents occur due to poor pre-construction planning
  • Insurance complications
  • Delays and additional costs from HSE enforcement action
  • Reputational damage

Appointment checklist

Before your project's pre-construction phase begins:

  1. 1

    Determine if you need a Principal Designer

    Will more than one contractor work on the project at any time? If yes, you must appoint one.

  2. 2

    Appoint early

    Appoint as soon as practicable, ideally before design work starts. Must be before construction phase begins at the latest.

  3. 3

    Check competence

    Take reasonable steps to verify they have the skills, knowledge, and experience for your project's complexity.

  4. 4

    Confirm they are a designer

    The appointee must be a designer with control over the pre-construction phase, not just a health and safety advisor.

  5. 5

    Make the appointment in writing

    Document the appointment clearly. Keep a copy for your records.

  6. 6

    Include in F10 notification

    If your project is notifiable, include the Principal Designer's contact details in your notification to HSE.

  7. 7

    Provide pre-construction information

    Give them all relevant information about the site and project so they can fulfil their duties.

Related guides

This guide focuses on appointing a Principal Designer. For related CDM requirements, see:

CDM 2015: your duties as a construction client (opens in a new tab)

You must also appoint a Principal Contractor for multi-contractor projects. The Principal Contractor coordinates health and safety during the construction phase.