Do I need a CDM Principal Designer?

The legal trigger is not project value, duration, planning permission or whether the project is notifiable to HSE. Under the Construction (Design and Management) Regulations 2015 (CDM 2015), a commercial client must appoint a Principal Designer in writing where a project involves, or is likely to involve, more than one contractor.

The appointment must be made as soon as practicable and, in any event, before the construction phase begins. HSE also advises appointment as early as possible in the design process and, where practicable, at concept stage. Early appointment matters because decisions about structure, access, sequencing, maintenance and temporary works can create or remove risk long before operatives arrive on site.

The Principal Designer must be a designer under CDM, have control over the pre-construction phase, and have the skills, knowledge and experience—and, for an organisation, organisational capability—needed for the particular project. A title on an appointment letter is not a substitute for real authority, time and competence.

A three-part decision test

If the answers are “yes”, “yes” and “commercial”, the client must make the written appointment. If the project is domestic, the Principal Designer function still needs to be dealt with, but CDM transfers client duties in the way explained below.

What does “more than one contractor” mean?

A contractor is a person or business that carries out, manages or controls construction work. In practical procurement terms, a project with a main builder plus separately engaged or subcontracted electrical, plumbing, roofing, scaffolding or groundworks businesses is likely to be a multi-contractor project.

The trades do not need to work at the same time for the trigger to matter. The question is whether the project involves, or is likely to involve, more than one contractor over its course. A client should therefore consider the intended supply chain, not just who is named when the first design is produced.

A genuine single-contractor project does not require a Principal Designer appointment under regulation 5. That does not remove the client's management duties, the designer's duties or the contractor's duty to prepare a Construction Phase Plan before construction starts.

What if the client is a homeowner?

A domestic client is someone having construction work carried out on their own home, or the home of a family member, where the work is not done in connection with a business. CDM still applies, but most domestic-client duties normally pass to other project duty holders.

On a domestic project involving more than one contractor, the Principal Contractor normally carries the client duties. Where the domestic client has not appointed a Principal Designer, HSE states that the Principal Designer role must be carried out by the designer in control of the pre-construction phase. A Principal Designer may also agree in writing to take on the domestic client's duties in addition to the Principal Designer duties.

Domestic status should not be assumed merely because the building is residential. Work commissioned as part of a landlord's, developer's or other business activity is generally a commercial-client project for CDM purposes.

Who appoints the Principal Designer, and when?

The client makes the appointment in writing. For a commercial multi-contractor project, the appointment should identify the project, the duty-holder role, the scope of authority, coordination arrangements and the period of appointment. It should be completed early enough for the Principal Designer to influence the design—not signed retrospectively after construction has started.

The role should continue for as long as Principal Designer functions need to be performed. Design often continues during construction through specialist design, temporary works, product substitutions and site-led changes. If the appointment ends before the project does, HSE says the Principal Designer should fully brief the Principal Contractor on relevant design matters and pass the Health and Safety File to them.

If a commercial client fails to appoint a Principal Designer when required, the client must fulfil the Principal Designer duties. Appointing someone unsuitable can also leave the client exposed because clients must take reasonable steps to ensure duty holders comply with their duties.

What should the CDM Principal Designer actually do?

The role is active coordination of health and safety during the pre-construction phase. HSE summarises the core functions as:

• planning, managing, monitoring and coordinating health and safety in the pre-construction phase;
• helping the client assemble relevant pre-construction information and ensuring designers and contractors receive what they need;
• working with designers to eliminate foreseeable risks where possible and reduce or control those that remain;
• ensuring cooperation and communication between those involved in pre-construction work;
• liaising with the Principal Contractor about risks that must be managed during construction; and
• preparing, reviewing and updating the Health and Safety File as the project progresses.

The CDM Principal Designer is not automatically responsible for managing the construction site, writing every contractor's RAMS, approving all designs or taking over the client's retained duties. Those responsibilities remain with the relevant duty holders. The scope must also not be confused with the separate Principal Designer role under the Building Regulations in England; one organisation may hold both appointments only where it is competent and separately appointed for each legal role.

Questions to ask before appointing

Before making the appointment, a client should test more than availability and price. Useful questions include:

• Does the proposed Principal Designer understand the project's construction methods, design disciplines and significant risks?
• Who will lead the role day to day, and do they have enough time and authority?
• How will design risks, actions and decisions be recorded and closed out?
• How will the Principal Designer obtain and distribute pre-construction information?
• How will they coordinate with the Principal Contractor when design continues during construction?
• What relevant competence, experience and organisational arrangements can they demonstrate?

For larger or higher-risk work, the competence review should be proportionate to the complexity and risk profile rather than relying only on a general qualification or professional membership.

What should I do next?

1. List every contractor and specialist business likely to carry out or control construction work.
2. Confirm whether the client is commercial or domestic and record the reasoning.
3. Identify which designer controls the pre-construction phase and whether it has suitable competence and capacity.
4. Make the required written appointments early, with a clear scope and authority.
5. Provide the project brief, surveys, existing information and known constraints so coordination can begin.

IMERI H&S Partners provides CDM Principal Designer services and pre-construction support for projects in Watford, Hertfordshire, London and the South East. If you are unsure whether the role is required, send us the project scope, procurement plan, known designers and anticipated contractors. We can review the position and propose a defined scope where support is needed.