The CDM Principal Designer and the Building Regulations Principal Designer share the same job title, but they are separate statutory roles with different purposes. The CDM role manages health and safety risk during the pre-construction phase, while the Building Regulations role manages and coordinates design work so that, if built, it complies with the Building Regulations.
The same person or organisation can carry out both roles on a project in England, but one appointment does not automatically cover the other. Government guidance confirms that where the CDM Principal Designer is also to act as the Building Regulations Principal Designer, the client must confirm that arrangement in writing.
Refurbishment works on a scaffolded building in the City of London. Photograph: London Construction Magazine
CDM Principal Designer and Building Regulations Principal Designer compared
| Point | CDM Principal Designer | Building Regulations Principal Designer |
|---|---|---|
| Legal regime | Construction (Design and Management) Regulations 2015 | Building Regulations 2010, as amended in England in 2023 |
| Main purpose | Manage and coordinate pre-construction health and safety risk | Manage and coordinate design compliance with Building Regulations |
| Geographical scope | Great Britain | The dutyholder regime discussed here applies in England |
| Who must hold the role? | A designer with control over the pre-construction phase | A designer with control over the design work |
| Core competence | Construction health and safety, design risk and pre-construction coordination | Building Regulations compliance and design coordination |
| Can the same organisation do both? | Yes, provided it is competent for both roles and the Building Regulations appointment is confirmed in writing | |
What does the CDM Principal Designer actually do?
Under Regulation 5 of CDM 2015, a client must appoint a Principal Designer in writing where more than one contractor is involved, or where it is reasonably foreseeable that more than one contractor will work on the project. The appointment must be made as soon as practicable and before the construction phase begins.
The Health and Safety Executive describes the CDM Principal Designer as the designer controlling the pre-construction phase. The role must plan, manage, monitor and coordinate health and safety during that phase, help the client assemble pre-construction information, coordinate designers, eliminate or reduce foreseeable risks and liaise with the Principal Contractor.
The focus is therefore not whether a design satisfies every technical requirement of the Building Regulations. It is whether design and planning decisions properly address foreseeable risks to people constructing, using, maintaining and eventually altering or demolishing the asset. LCM's separate guide to Principal Designer duties under CDM examines those pre-construction responsibilities in more detail.
What does the Building Regulations Principal Designer do?
The Building Regulations role was introduced into Part 2A of the Building Regulations 2010 by the Building Regulations etc. (Amendment) (England) Regulations 2023. Its purpose is different. Building Safety Regulator guidance says the Principal Designer must be part of the design team and must have enough influence over design decisions to plan, manage, monitor and coordinate design work.
Regulation 11M requires the Building Regulations Principal Designer to coordinate the design so that all reasonable steps are taken to ensure that, if the building work were carried out in accordance with the design, it would comply with the relevant requirements. Individual designers remain responsible for their own design work; the Principal Designer coordinates the overall compliance process.
There is an important appointment point here. Regulation 11D, introduced by the 2023 amendment regulations, requires the client to appoint a designer with control over the design work as Principal Designer where more than one contractor is involved or is reasonably foreseeable. Government guidance also explains that where only one designer is involved, that designer performs the Principal Designer function, and describes written appointments where more than one designer or contractor is working on the project.
LCM clarification: the safest way to understand the regime is not to decide whether the role exists by counting architects and engineers alone. Regulation 11D's formal appointment trigger is linked to contractor numbers, while the wider Part 2A regime still places design-compliance duties on designers and requires clear control of design work. The appointment and scope should therefore be resolved before work begins, not reconstructed later from project titles.
Can the same Principal Designer perform both roles?
Yes. The legislation expressly allows it. Regulation 11D permits a client to certify in writing that the person who is the CDM Principal Designer is also treated as appointed as Principal Designer for Building Regulations purposes. The Government's guidance makes the same point.
That does not mean two completely separate appointment documents are legally required. A properly drafted appointment can address both regimes. What matters is that it is explicit about which statutory roles are being accepted and that the appointee is competent to perform both.
An appointment letter saying only “Principal Designer” creates avoidable uncertainty. A client should be able to establish immediately whether the consultant is appointed under CDM 2015, the Building Regulations 2010, or both. On complex projects this distinction also affects design responsibility, information management, insurance and regulatory submissions. LCM has previously examined how the two Principal Designer responsibilities interact on higher-risk buildings.
The competence tests are different
Competence for the two roles should not be treated as interchangeable. CDM competence is centred on the ability to manage pre-construction health and safety risk. Building Regulations competence requires the skills, knowledge, experience and behaviours needed to manage design compliance, or appropriate organisational capability where an organisation is appointed.
There is no general rule that a Building Regulations Principal Designer must hold a particular professional title or specific training certificate. Government guidance says Principal Designers are not expected to be specialists in every design discipline, but they must know enough about the Building Regulations to assess and coordinate compliance across the design team.
PAS 8671 is also frequently misunderstood. The Government describes PAS 8671 as a recommended competence framework that can help demonstrate and assess Principal Designer competence. Compliance with PAS 8671 does not, by itself, guarantee that statutory competence requirements have been met.
What changes on a higher-risk building?
The distinction becomes particularly important on higher-risk building work. For projects requiring Building Safety Regulator building control approval, the Building Regulations Principal Designer must be appointed before the building control approval application is submitted.
The Building Regulations Principal Designer also has additional higher-risk building duties, including operating a mandatory occurrence reporting system, making required reports to the Building Safety Regulator and maintaining design information within the golden thread. BSR guidance for higher-risk building design and construction sets out the wider regulatory process.
A CDM Principal Designer appointment does not, by itself, make that consultant responsible for Gateway 2, Building Regulations compliance or the higher-risk building golden thread. Those obligations arise from the Building Regulations role where the same party has also been properly appointed to it. LCM's analysis of Building Regulations Principal Designer appointments at Gateway 2 explains why simply having the title on an organisation chart is not enough if the project cannot demonstrate genuine design control.
What happens if no Principal Designer is appointed?
For a commercial project under CDM 2015, if the client fails to appoint a required Principal Designer, the client must fulfil the Principal Designer duties. The Building Regulations contain a similar mechanism: where the client fails to make the required appointment, the client must fulfil the Principal Designer duties until another person is appointed.
Domestic projects work differently. Under CDM, where a domestic client does not appoint a Principal Designer on a multi-contractor project, the designer in control of the pre-construction phase carries out the role. Under the Building Regulations dutyholder regime, the designer in control of the design phase becomes the Principal Designer where the domestic client does not make the appointment.
For clients and consultants, the practical next step is straightforward: check the appointment before design responsibility becomes fragmented. The document should identify the statutory regime, the scope of the role, who controls the relevant phase, how competence has been assessed and whether the same organisation is accepting both Principal Designer duties. On higher-risk buildings, that position needs to be settled before the Building Safety Regulator application, not after it.
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Expert Verification & Authorship: Mihai Chelmus Founder & Editor, London Construction Magazine | Construction Testing & Investigation Specialist |