Principal Designer duties under CDM 2015

What is a Principal Designer under CDM 2015?

Under the Construction (Design and Management) Regulations 2015 (CDM 2015), the principal designer is the designer appointed by the client to take control of the pre-construction phase on a project involving, or likely to involve, more than one contractor. HSE guidance: principal designers, roles and responsibilities (opens in a new tab)

The role can be carried out by an organisation or an individual. The principal designer must be a designer as defined by CDM and must have the skills, knowledge and experience needed for the role, together with organisational capability where the appointment is an organisation. HSE guidance: are you a principal designer? (opens in a new tab)

The principal designer does not have to produce every design on the project. Their key function is to plan, manage, monitor and coordinate health and safety during the pre-construction phase and to make sure the design team works together to manage foreseeable risks.

Principal Designer duties: Regulation 11 at a glance

When is a Principal Designer required?

A client must appoint a principal designer in writing where a construction project involves, or is likely to involve, more than one contractor. The appointment should be made as early as possible in the design process and, where practicable, at concept stage. Read Regulation 5 on legislation.gov.uk: appointment of the principal designer and the principal contractor (opens in a new tab)

This requirement is not limited to large or notifiable projects. A comparatively small refurbishment, maintenance or fit-out project may still require a principal designer if more than one contractor is involved or is likely to be involved.

If a commercial client fails to make the required appointment, the client takes on the principal designer duties that should have been allocated to the role. Read Regulation 5 on legislation.gov.uk: appointment of the principal designer and the principal contractor (opens in a new tab)

Need to make the appointment? Download our free one-page Principal Designer Appointment Letter.

What are the Principal Designer’s main duties?

The principal designer’s duties are centred on the pre-construction phase, but the role can continue into the construction phase where design work is still being developed or changed. In practice, the principal designer needs arrangements that allow them to remain involved for as long as their CDM functions are required.

The core duties include:

• planning, managing, monitoring and coordinating health and safety in the pre-construction phase;
• using relevant pre-construction information when coordinating design work;
• helping the client assemble and provide pre-construction information;
• working with designers to eliminate foreseeable risks where possible and reduce or control risks that remain;
• ensuring designers cooperate, communicate and coordinate their work;
• checking that designers are carrying out their CDM duties;
• liaising with the principal contractor about design risks and information relevant to the construction phase; and
• preparing, reviewing and updating the health and safety file where required.

Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

Plan, manage, monitor and coordinate the pre-construction phase

The principal designer must put suitable arrangements in place for managing health and safety during the pre-construction phase. This means more than holding occasional design meetings or collecting risk registers. Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

The arrangements should be proportionate to the scale, complexity and risks of the project and should support an effective design process. The principal designer needs sufficient visibility of the design work to identify where coordination is required, where information is missing and where significant or foreseeable risks need further attention.

In doing so, the principal designer must take account of the general principles of prevention, particularly when design, technical and organisational decisions are made about which stages of work will run at the same time or in sequence, and when estimating how long they will take. Where relevant, the content of any construction phase plan and health and safety file must also be taken into account. Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

Monitoring should also be active. If design decisions, interfaces or information flows are not being managed effectively, the principal designer should intervene and coordinate the people involved rather than simply record the issue.

Help the client with pre-construction information

The client is responsible for providing pre-construction information, but the principal designer has an important supporting role. They should help the client identify, assemble and distribute information that designers and contractors need to carry out their duties. HSE guidance: principal designers, roles and responsibilities (opens in a new tab)

Relevant information may include existing drawings, surveys, asbestos information, structural information, information about existing services, site constraints, access arrangements and an existing health and safety file.

The principal designer should also help identify gaps. Where information is missing but reasonably obtainable and necessary for safe design or planning, the project team should address that gap rather than allow design work to proceed on unsupported assumptions.

Our editable PCI Word template includes a register for recording significant information gaps, the action needed, an owner and a target date.

Coordinate designers and design work

One of the principal designer’s most important functions is to coordinate the design team. Individual designers retain their own CDM duties, but the principal designer must make sure their work is coordinated and that health and safety information is communicated between disciplines. Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

This is particularly important where one design affects another. Structural, architectural, mechanical, electrical, temporary works, specialist and contractor-designed elements can create interfaces that no single designer can manage in isolation.

Effective coordination may involve design reviews, risk workshops, clash or interface reviews, agreed design information requirements, action tracking and direct discussion between designers. The exact process should suit the project rather than become paperwork for its own sake.

Eliminate, reduce and control foreseeable design risks

CDM places duties on designers to eliminate foreseeable health and safety risks where reasonably practicable and, where risks cannot be eliminated, to reduce or control them. The principal designer must coordinate this process across the design team. Read Regulation 9 on legislation.gov.uk: duties of designers (opens in a new tab)

The aim is not to produce a design with no risk. Construction, maintenance, use and eventual demolition will always involve risk. The principal designer should instead focus attention on significant and foreseeable risks that can be influenced through design.

Examples might include access for installation and maintenance, structural stability during sequencing, heavy or difficult-to-handle components, work at height, existing services, confined spaces, future cleaning and maintenance access, or interfaces between different systems.

The principal designer should also avoid encouraging indiscriminate design-risk paperwork. Information should be proportionate and useful to those who need it, particularly where a residual risk is unusual, significant or not likely to be obvious to a competent contractor. HSE designer guidance: designers, roles and responsibilities (opens in a new tab)

Worked example: coordinating rooftop plant replacement

Ensure designers comply with their duties

The principal designer is expected to take reasonable steps to ensure designers on the project comply with their CDM duties. That does not mean the principal designer becomes responsible for producing or approving every design on behalf of each designer. Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

It does mean they need enough oversight to identify whether designers are considering pre-construction information, applying the general principles of prevention, coordinating with others and communicating information about significant residual risks.

Where a designer is not meeting those expectations, the principal designer should raise the issue and coordinate the action needed to address it.

Liaise with the Principal Contractor

The principal designer and principal contractor have different areas of control, but their duties overlap at the interface between design and construction. The principal designer should liaise with the principal contractor and provide information about design matters and risks that need to be managed during the construction phase. Read Regulation 11 on legislation.gov.uk: duties of a principal designer in relation to health and safety at the pre-construction phase (opens in a new tab)

The principal contractor can also provide valuable construction knowledge back into the design process, particularly around sequencing, temporary works, access, logistics and buildability. Good CDM coordination should therefore work in both directions rather than treating design and construction as separate silos. HSE principal contractor guidance: principal contractors, roles and responsibilities (opens in a new tab)

Where design continues during construction, this liaison becomes particularly important because the pre-construction phase can continue for those elements even after physical construction has started.

Prepare and update the health and safety file

For projects involving more than one contractor, the principal designer is normally responsible for preparing the health and safety file during the project. The file should contain information likely to be needed to protect health and safety during future construction work, such as maintenance, refurbishment or demolition. Read Regulation 12 on legislation.gov.uk: construction phase plan and health and safety file (opens in a new tab)

The file should be developed as the project progresses rather than assembled as an afterthought at handover. Information should be relevant, proportionate and useful for future work.

If the principal designer’s appointment ends before the end of the project, responsibility for the file passes to the principal contractor, who must then complete it and pass it to the client. Read Regulation 12 on legislation.gov.uk: construction phase plan and health and safety file (opens in a new tab)

How long does the Principal Designer role last?

The principal designer should remain appointed for as long as they are needed to carry out the role. Although the title focuses on the pre-construction phase, design work often continues after construction has begun. HSE guidance: principal designers, roles and responsibilities (opens in a new tab)

A client should therefore avoid ending the appointment automatically at the start of site work if significant design coordination remains. The scope and duration of the appointment should reflect the actual project and the design work still to be completed.

What skills, knowledge and experience does a Principal Designer need?

The principal designer must have the skills, knowledge and experience necessary to carry out the role in a way that secures health and safety. Where the principal designer is an organisation, it must also have the organisational capability needed for the project. Read Regulation 8 on legislation.gov.uk: general duties, including skills, knowledge and experience (opens in a new tab)

The level required should be proportionate to the project. A complex infrastructure, high-rise or technically unusual project will require different capability from a straightforward small refurbishment.

Relevant evidence might include experience of comparable projects, technical construction knowledge, understanding of design risk management and CDM, competent people within the organisation, suitable processes and resources, and relevant continuing professional development.

CDM Principal Designer vs Building Regulations Principal Designer

The term “principal designer” is now used in two different legal frameworks in England, so it is important not to assume the roles are interchangeable.

This guide covers the principal designer role under CDM 2015, which is focused on managing health and safety during the pre-construction phase of construction projects.

A separate principal designer role exists under the Building Regulations framework. That role has different legal functions relating to compliance with the Building Regulations. The same person or organisation may sometimes hold both appointments where they are competent and properly appointed for each role, but one appointment does not automatically satisfy the other.

Principal Designer duties checklist

As a practical sense-check, a CDM principal designer should be able to demonstrate arrangements covering the following:

Appointment and capability

• The appointment is clear, in writing and made early enough to influence the project.
• The scope and duration of the principal designer role match the design work required.
• There is suitable evidence that the principal designer has the skills, knowledge, experience and organisational capability required for the project.

Pre-construction information

• Relevant pre-construction information has been identified, reviewed and shared.
• Gaps in important project information are identified and managed.

Design coordination

• Designers understand their CDM duties and cooperate with one another.
• Design interfaces and significant foreseeable risks are actively coordinated.
• Design changes during construction continue to be coordinated where required.

Design risk

• Designers are taking reasonable steps to eliminate, reduce or control foreseeable risks.
• Significant residual risk information is communicated in a useful and proportionate way.

Liaison and the health and safety file

• There is effective liaison with the client and principal contractor.
• The health and safety file is being developed as the project progresses.

A checklist can support governance, but it does not replace professional judgement. The arrangements need to reflect the project, the design team and the risks involved.

Common Principal Designer mistakes

Treating the role as a document-management exercise

Collecting risk registers and meeting minutes is not the same as coordinating health and safety through design. The role needs active involvement in how designers communicate, make decisions and manage significant foreseeable risks.

Being appointed too late

If the principal designer joins after key design decisions have already been fixed, opportunities to eliminate or reduce risk may already have been lost. Early appointment gives the role meaningful influence.

Assuming every design risk must be transferred to the contractor

Designers should first consider whether foreseeable risks can be eliminated or reduced through design. Residual information should focus on what others genuinely need to know, rather than shifting every possible risk into notes and registers.

Ending the appointment when site work starts

The pre-construction phase can continue for design work carried out during construction. The appointment should reflect the real duration of the principal designer’s functions.

Confusing the CDM and Building Regulations roles

Using the same title for two legal roles can create gaps in responsibility. Appointment documents and project governance should distinguish clearly between them.