CDM Principal Designer vs Building Regulations Principal Designer

There are two separate Principal Designer roles on projects in England. The CDM Principal Designer manages and coordinates health and safety during the pre-construction phase under the Construction (Design and Management) Regulations 2015. The Building Regulations Principal Designer manages and coordinates design work so that it complies with the Building Regulations.

The roles overlap because both involve the design team, information and coordination. Their legal tests, objectives and required competence are nevertheless different. Naming an architect, consultant or other organisation as “Principal Designer” without identifying the applicable regulations leaves a dangerous ambiguity.

What is the difference?

The CDM Principal Designer

HSE describes the CDM Principal Designer as the designer appointed by the client to take control of the pre-construction phase on a project involving more than one contractor. Its main functions include:

• planning, managing, monitoring and coordinating health and safety in the pre-construction phase;
• helping the client assemble and provide relevant pre-construction information;
• working with designers to eliminate foreseeable risks where possible and reduce or control those that remain;
• ensuring designers communicate and cooperate;
• liaising with the Principal Contractor about risks that need managing during construction; and
• preparing, reviewing and updating the Health and Safety File.

This is not a general design-approval role. The CDM Principal Designer coordinates how health and safety is addressed through design and pre-construction decisions; each designer remains responsible for complying with their own CDM duties.

The Building Regulations Principal Designer

The Building Regulations duty-holder regime described here applies in England. The Principal Designer must be part of the design team and must plan, manage, monitor and coordinate matters relating to the design work. Official guidance identifies duties including:

• taking reasonable steps to ensure designers comply with their Building Regulations duties;
• assessing design work so that designers produce compliant designs;
• coordinating and sharing relevant information with the Principal Contractor;
• supporting cooperation and communication between clients, designers and contractors; and
• considering comments from the Principal Contractor relating to Building Regulations compliance.

The role does not replace the duties of individual designers, the client, contractors or building control. It also does not mean that the Principal Designer personally designs every element or gives a guarantee that approval will be granted.

When does the client need to appoint each role?

CDM appointment trigger

For a commercial project involving, or likely to involve, more than one contractor, the client must appoint a CDM Principal Designer in writing. The appointment must be made as soon as practicable and before the construction phase begins. The trigger concerns the number of contracting businesses across the project, including subcontractors—not simply the number of direct contracts held by the client.

Our separate guide explains the CDM test, including domestic-client arrangements: Do I need a CDM Principal Designer?

Building Regulations appointment trigger in England

For design and building work covered by the Building Regulations duty-holder regime, official guidance says that where more than one designer or contractor works on the project, the client must appoint in writing a Principal Designer to control the design work and a Principal Contractor to control the building work. Where there is only one designer, that designer is the Principal Designer; where there is only one contractor, that contractor is the Principal Contractor.

The Building Regulations role is not restricted to higher-risk buildings. Higher-risk building work brings additional procedures and duties, but the core duty-holder requirements apply more widely to building work in England that is within the Building Regulations regime.

Can the same organisation be appointed for both?

Yes, but it is not automatic. GOV.UK confirms that the CDM Principal Designer and Principal Contractor can also carry out the corresponding Building Regulations roles. If they are the same, the client must confirm this in writing. The appointee must still be competent for both legal functions.

A familiar name or an existing CDM appointment is not enough. The proposed appointee may be strong in construction health and safety coordination but lack the technical Building Regulations knowledge or design-control capability needed for the Building Regulations role. The reverse can also be true: a technically capable lead designer may not have suitable CDM risk-management arrangements.

A clear dual appointment should identify:

• the exact organisation appointed under each set of regulations;
• the scope, start point, duration and limits of each appointment;
• the competent individuals who will lead the functions where an organisation is appointed;
• access to the design team, client and Principal Contractor;
• information, meeting, review and change-control arrangements; and
• how gaps, conflicts and unresolved risks or compliance matters will be escalated.

Do the competence requirements differ?

Yes. Both regimes require competence, but it must be assessed against the work and the particular legal role.

For CDM, an individual needs the skills, knowledge and experience—and an organisation needs the organisational capability—necessary to perform the role in a way that secures health and safety. The assessment should reflect the project's scale, complexity and risk profile.

Under the Building Regulations regime, individuals must have the necessary skills, knowledge, experience and behaviours, while organisations must have the organisational capability to carry out their functions. The Building Regulations Principal Designer is expected to understand enough of the technical and regulatory framework to assess and coordinate whether design work complies with relevant requirements. Official guidance also stresses that the appointee should be part of the design team, not a detached third party with no influence over design decisions.

How should separate Principal Designers work together?

Where different organisations hold the two roles, GOV.UK says they need to work together and share relevant information. A sensible coordination arrangement should prevent two parallel design-management systems from missing the same change.

In practice, clients and design teams should agree:

• a coordinated design programme and responsibility matrix;
• which meetings each Principal Designer attends and chairs;
• how CDM design risks and Building Regulations compliance matters are recorded;
• how technical queries, design changes and contractor proposals are reviewed;
• what information moves to the Principal Contractor and when;
• how unresolved matters are reported to the client; and
• handover arrangements if either appointment changes.

One issue may engage both regimes. A change to a façade, stair, structural opening or maintenance-access arrangement could affect Building Regulations compliance and create construction or future-use risks. The two Principal Designers should coordinate their reviews without assuming that one legal test satisfies the other.

What about higher-risk buildings?

Higher-risk building work in England brings additional Building Safety Regulator procedures, including competence declarations, change control, mandatory occurrence reporting and golden-thread information requirements. Those extra requirements do not remove or merge the CDM duties. The project still needs both regimes to be addressed by appropriately competent duty holders.

A client checklist before design progresses

1. Confirm whether the work is a CDM construction project and whether more than one contractor is likely.
2. Confirm that the project involves work within the Building Regulations duty-holder regime in England.
3. Name the proposed appointee for each Principal Designer role—do not use an unexplained “PD” abbreviation.
4. Assess competence and organisational capability separately against each role and the project risks.
5. Make the required written appointments and give the appointees sufficient authority, time and information.
6. Agree how the two functions will coordinate design reviews, changes and information supplied to the Principal Contractor.
7. Revisit the arrangements if the design lead, procurement route, contractor structure or project classification changes.

IMERI H&S Partners provides CDM Principal Designer services for projects in Watford, Hertfordshire, London and the South East. Our service is concerned with the CDM 2015 role. Where a Building Regulations Principal Designer is also required, that appointment and its competence assessment must be dealt with expressly rather than assumed to be included.