What is a CDM Principal Designer?
Understanding the Principal Designer role under the CDM Regulations
Part of our Consultants series
Successful building projects rely on clear roles and responsibilities. Among these, the Principal Designer is a legally defined duty holder under the Construction Design and Management Regulations 2015, often known as CDM 2015. This role exists to ensure that health and safety are considered and coordinated during the design stage of a project.
Although architects frequently act as Principal Designer, they are not the only professionals who may do so. Engineers, project managers, building surveyors, and specialist construction health and safety consultants may also take this appointment, provided they are suitably competent.
This article forms part of our Consultants series, which explains key specialist roles in high end residential projects and how they interact with the architect.
Why the CDM Regulations exist
The CDM Regulations were introduced to raise health and safety standards across the construction industry and to ensure that risk management begins at the earliest stage of a project. Historically, safety planning was often left to the construction phase. CDM 2015 shifted responsibility upstream so that designers and clients must consider how a building will be constructed, used, maintained, and ultimately adapted or removed.
The aim is to eliminate hazards where possible, reduce unavoidable risks, and ensure that clear information is provided to those responsible for building the project.
When a Principal Designer is required
A Principal Designer must be appointed on any project where more than one contractor will be working. This applies to almost all residential refurbishments, extensions, and new build homes.
The client must appoint the Principal Designer in writing before construction begins. If the client does not make a formal appointment, they automatically take on the legal duties themselves.
Domestic clients benefit from some simplified arrangements, but on higher value or more complex residential projects, it remains essential that formal appointments are made early and that they are made to competent people.
What the Principal Designer does
The Principal Designer plans, manages, monitors, and coordinates health and safety during the pre construction phase. Their responsibilities include
Ensuring that foreseeable risks are identified and addressed through design
Coordinating and communicating with the wider design team so that each designer understands and fulfils their legal duties
Assisting and advising the client regarding their own responsibilities under CDM
Preparing and updating the pre construction information pack
Working with the client to ensure the Principal Contractor receives the information required to plan safe construction methods
Collating information for the health and safety file that must be provided to the client at the end of the project
The role does not replace the duties of individual designers. Instead, it ensures that there is clear leadership and coordination so that risks are not overlooked or duplicated.
The link between the Principal Designer and the architect
In many projects, the architect naturally acts as Principal Designer because the architect leads the design team and is already responsible for coordinating information. The role sits comfortably alongside the task of ensuring that the project design is well managed, clear, and coordinated.
However, the Principal Designer appointment introduces distinct statutory duties. These include structured record keeping, risk reviews, and formal communication processes. An architect who accepts this role must therefore be trained and equipped to deliver it in a compliant manner.
Other professionals who may act as Principal Designer
The CDM Regulations do not state that the Principal Designer must be an architect. The only legal requirement is that the appointed party is competent.
Depending on the project, this role may be performed by
A project manager with design coordination experience
A structural or civil engineer, particularly on technically complex projects
A building surveyor, especially on refurbishment schemes with limited architectural scope
A specialist health and safety consultant with expertise in design stage coordination
On some larger projects the Principal Designer role may be fulfilled by a multidisciplinary consultancy with both design and safety specialists.
The key requirement is that the party has the right skills, knowledge, experience, and organisational capability to manage the role.
The F10 form
For any notifiable project under CDM 2015, the client must ensure that the F10 notification form is submitted to the Health and Safety Executive.
A project becomes notifiable when
Construction work lasts longer than thirty working days and involves more than twenty people working simultaneously, or
The project exceeds five hundred person days of construction work in total
The Principal Designer usually prepares and submits the F10 form on behalf of the client, but it remains the client’s legal responsibility to ensure this has been done.
Working with the Principal Contractor
Once construction begins, the Principal Contractor takes charge of health and safety on site. The Principal Designer continues to contribute where relevant, particularly if design information evolves during the build.
Clear communication between the Principal Designer and Principal Contractor helps ensure that design intent, risk control measures, and any changes are properly understood and implemented.
Why appointing the right Principal Designer matters
Appointing an experienced Principal Designer helps ensure
Fewer delays due to safety related issues
Better coordination between designers and contractors
Increased clarity for clients regarding legal duties
Safer construction methods and future maintenance strategies
Well documented decision making and risk management
For high end residential projects, this role provides reassurance that complex elements such as deep basements, existing building interfaces, bespoke details, and specialist materials have been assessed from a safety perspective from the very beginning.
What clients need to know
On any project with more than one contractor, the client must
Appoint a competent Principal Designer in writing
Provide relevant information about the site and any existing structures
Allow sufficient time and resources for proper design and planning
Ensure the F10 form is submitted where required
Work collaboratively with the Principal Designer and Principal Contractor
If no Principal Designer is appointed, the client assumes the duties themselves. It is therefore essential that the appointment is made and that it is made early.
Summary
The Principal Designer role ensures that safety is considered during design and that risks are addressed before construction begins. Although architects commonly fulfil this role, it may also be performed by other suitably competent professionals.
The formal appointment of a Principal Designer, along with the correct submission of the F10 form where required, is a legal obligation and a key element of a well structured residential project.