Quick summary: Principal Designer CDM Regulations
Under the Principal Designer CDM Regulations, a Principal Designer is required on a construction project where more than one contractor is, or is reasonably foreseeable to be, involved. Under the Construction (Design and Management) Regulations 2015 (CDM 2015), the Principal Designer takes the lead in planning, managing, monitoring and co-ordinating health and safety during the pre-construction phase.
- When required: where a project involves, or is expected to involve, more than one contractor.
- Main CDM role: co-ordinate health and safety during the design and pre-construction stages.
- Who can do it: an individual or organisation that is a designer and has the skills, knowledge, experience and, where relevant, organisational capability to perform the role properly.
- Domestic projects are covered: CDM 2015 also applies to work carried out for homeowners, although some client duties transfer automatically to other project dutyholders.
- Do not confuse the roles: the CDM Principal Designer and the Building Regulations Principal Designer are separate legal functions, even though the same competent person or organisation may sometimes perform both.
For homeowners, the important point is not simply who has “Principal Designer” written beside their name. You need to know which legal role they have been appointed to perform, what duties that appointment covers and whether they are competent for your particular project.
Unsure who should take responsibility for design-stage compliance?
We can help you understand which design and Building Regulations roles apply to your home project before work gets underway.
What is a Principal Designer under the CDM Regulations?
The Principal Designer CDM Regulations requirements come from the Construction (Design and Management) Regulations 2015, usually shortened to CDM 2015. These regulations are designed to make health and safety part of the way construction projects are planned, designed and managed rather than something considered only after builders arrive on site.
The Principal Designer is the designer appointed to be in control of the pre-construction phase where a project involves more than one contractor. In simple terms, they help make sure foreseeable health and safety risks are considered while design decisions are still being made.
For a homeowner project, this could involve an extension, loft conversion, major refurbishment or other building work involving an architectural designer, structural engineer and several trades.
CDM is therefore relevant alongside the wider approval process covered in our complete guide to complying with Building Regulations. However, the two legal regimes should not be treated as interchangeable.
When is a Principal Designer required under CDM?
A Principal Designer appointment is required where more than one contractor is, or it is reasonably foreseeable that more than one contractor will be, working on the project at any time.
Importantly, this does not mean that two builders have to be physically working in your house on the same day. A project involving different contractors at different stages can still be a multi-contractor project.
Examples of projects where the CDM Principal Designer role may arise
- an extension involving a main builder plus separate electrical, plumbing or roofing contractors;
- a loft conversion involving structural, roofing and specialist trades;
- a renovation where several separately appointed trades are used;
- a garage or basement conversion involving several contractors; or
- a larger residential project with an architect, engineer and multiple construction contractors.
What if there is no Principal Designer appointment?
Domestic clients receive special treatment under CDM 2015. Where the required appointments are not made by a domestic client, the regulations provide for the relevant duties to pass to the designer controlling the pre-construction phase and the contractor controlling the construction phase.
However, relying on a role arising by default is rarely the clearest way to run a project. Establishing responsibilities early helps everybody understand who is controlling design risk, who is controlling the construction stage and how important project information will be exchanged.
What are the Principal Designer duties under CDM 2015?
The Principal Designer has a management and co-ordination role. They are not expected to personally design every element of the project or remove every possible construction risk.
Instead, the role centres on ensuring that health and safety is properly considered as the design develops.
Principal Designer CDM responsibilities include:
- planning, managing and monitoring the pre-construction phase;
- co-ordinating health and safety matters during that phase;
- helping designers apply the general principles of prevention when foreseeable risks are considered;
- making sure designers have relevant pre-construction information;
- helping ensure designers fulfil their own CDM duties;
- working with the Principal Contractor and sharing relevant health and safety information;
- liaising with the client about information required for safe design and construction; and
- preparing, reviewing and updating the health and safety file where the regulations require one.
What does that mean in a normal home project?
Imagine that an extension requires a large steel beam. The structural engineer may design the beam, while the architectural designer considers the layout and the builder considers how it can actually be installed.
The Principal Designer's role is not necessarily to calculate that beam. Instead, they should help ensure that significant foreseeable risks created by the design are identified, considered, communicated and co-ordinated between the relevant people.
Who can be a Principal Designer under CDM 2015?
The role is not reserved exclusively for architects. A Principal Designer may be an individual or an organisation, provided they meet the legal requirements for the role and are capable of controlling the pre-construction phase.
Under CDM 2015, designers and contractors accepting appointments must have the necessary skills, knowledge and experience. Where an organisation is appointed, it must also have the necessary organisational capability.
A suitable CDM Principal Designer therefore needs to be able to:
- understand the design and construction issues relevant to the project;
- identify and manage foreseeable health and safety risks arising from design;
- co-ordinate several designers where necessary;
- communicate effectively with the client and construction team;
- understand their duties under CDM 2015; and
- devote sufficient time and resources to the role.
A job title by itself is not proof of competence. Likewise, appointing somebody simply because they produced the drawings does not automatically mean they are suitable to manage the CDM pre-construction function.
If your project is also moving towards a Building Control submission, our guide to preparing for the Building Regulations application process explains the wider approval route.
Principal Designer CDM and Building Regulations: what is the difference?
This is now one of the most important distinctions for homeowners to understand.
Since changes to the Building Regulations dutyholder regime in England, the term Principal Designer is used in two different regulatory systems.
CDM Principal Designer vs Building Regulations dutyholder
Under CDM 2015:
- the focus is health and safety;
- the Principal Designer controls the pre-construction phase;
- foreseeable risks arising from design must be managed and co-ordinated; and
- the role works closely with the Principal Contractor responsible for the construction phase.
Under the Building Regulations dutyholder regime in England:
- the focus is Building Regulations compliance;
- the Principal Designer manages and co-ordinates design work in relation to compliance;
- designers must work together so that the design, if built, complies with the applicable requirements; and
- specific competence requirements apply to the Building Regulations role.
So, although the titles sound identical, the legal responsibilities are not.
For more detail on the second role, see our separate explanation of the Building Regulations design dutyholder. You may also find our guide to the difference between planning approval and Building Regulations useful if you are still working out which permissions apply.
Not sure which Principal Designer role applies?
We can help you separate the CDM responsibilities from the Building Regulations requirements and make sure the design stage of your home project is properly organised.
Can the Principal Designer also be the Principal Contractor?
Potentially, yes. CDM 2015 does not create a blanket rule preventing the same person or organisation from performing both roles.
However, they must actually satisfy the requirements of each role. The Principal Designer must be a designer with control over the pre-construction phase, while the Principal Contractor must be a contractor with control over the construction phase.
Therefore, one business taking both appointments can make sense on some design-and-build projects. On others, separate appointments will be more appropriate.
Principal Designer CDM requirements: homeowner step-by-step checklist
You do not need to become a CDM expert before extending or renovating your home. However, asking a few sensible questions at the beginning can prevent confusion later.
Step-by-step: checking the Principal Designer arrangements
- List who will be involved. Identify the designers, builders and specialist contractors you expect to use.
- Decide whether multiple contractors are foreseeable. Do not look only at who will be on site first. Consider the whole construction project.
- Identify who controls the design phase. Establish who is actually in a position to plan, manage, monitor and co-ordinate pre-construction health and safety matters.
- Check competence. Ask how the proposed dutyholder's skills, knowledge, experience and resources relate to your type of project.
- Make responsibilities clear in writing. Avoid relying simply on assumptions or informal conversations about who is “handling CDM”.
- Clarify whether the Building Regulations role is separate. If the same organisation is taking both appointments, make sure this is explicit.
- Keep information flowing. Surveys, structural information, design changes and significant risks should reach the people who need them.
- Keep your project records. Retain drawings, approvals and compliance information for future reference.
Our guide to the project certificates and compliance documents worth keeping explains what homeowners should retain once construction progresses towards completion.
Common Principal Designer CDM mistakes to avoid
Assuming CDM does not apply to domestic projects
CDM 2015 does cover domestic construction work. The way some client duties operate is different for domestic clients, but the project is not simply outside CDM because the client is a homeowner.
Confusing the CDM role with Building Regulations compliance
This is increasingly common because both regimes use the terms Principal Designer and Principal Contractor. Always establish which appointment is being discussed.
Choosing somebody who cannot control the design phase
The Principal Designer needs meaningful influence over the design process. A nominal appointment made to somebody who is not genuinely involved in controlling or co-ordinating the design is unlikely to achieve the purpose of the role.
Making the appointment too late
The value of the role is greatest while important design decisions are still being made. Leaving health and safety co-ordination until construction is about to start can mean significant risks have already been designed into the project.
Failing to communicate design changes
Extensions and renovations often change once walls are opened or structural conditions become clearer. Those changes should be communicated to the relevant designers and contractors rather than being treated as isolated site decisions.
Where design changes affect technical compliance as well, our guide to how Building Control works during a project provides useful background.
Principal Designer CDM Regulations: what homeowners should remember
The Principal Designer role under CDM 2015 is fundamentally about managing and co-ordinating health and safety during the design and pre-construction phase.
For most homeowners, the key question is whether more than one contractor will be involved. If so, the Principal Designer and Principal Contractor arrangements need to be considered from the outset rather than once building work is already underway.
Equally, do not confuse a CDM appointment with the separate Principal Designer role now used within the Building Regulations dutyholder regime in England. One competent organisation may sometimes perform both, but the duties, appointments and purpose of the roles remain distinct.
Getting those responsibilities clear early makes it easier for your architectural designer, engineers and contractors to exchange information, manage changes and keep the project moving in a controlled way.
FAQs: Principal Designer CDM Regulations
What is a Principal Designer under CDM?
Under CDM 2015, the Principal Designer is the designer appointed by the client to control the pre-construction phase on a project involving more than one contractor. Their central role is to plan, manage, monitor and co-ordinate health and safety during that phase.
When is a Principal Designer required under CDM?
A Principal Designer is required where more than one contractor is, or it is reasonably foreseeable that more than one contractor will be, working on a construction project. The appointment should therefore be considered early, while the project team and design process are being organised.
Who can be a Principal Designer under CDM 2015?
The role can be undertaken by an individual or organisation that is a designer and has the appropriate skills, knowledge and experience to fulfil the appointment. An organisation must also have sufficient organisational capability. Most importantly, the appointee must be capable of controlling the pre-construction phase.
What are the Principal Designer duties under CDM?
The duties centre on planning, managing, monitoring and co-ordinating the pre-construction phase, helping designers manage foreseeable health and safety risks, ensuring relevant information is available and co-operating with the Principal Contractor and other members of the project team.
Can the Principal Designer and Principal Contractor be the same?
They can potentially be the same individual or organisation where that party meets the requirements of both roles and is genuinely capable of controlling the relevant design and construction phases. Combining the roles does not remove any of the individual legal duties.
Is the CDM Principal Designer the same as the Building Regulations Principal Designer?
No. The CDM role is concerned primarily with health and safety arising from design and construction. The Building Regulations role in England is concerned with managing and co-ordinating design work so that it complies with the relevant Building Regulations requirements. The same competent person or organisation may sometimes fulfil both roles, but they are separate legal functions.
When is a Building Regulations Principal Designer required?
In England, the Building Regulations dutyholder framework requires a Principal Designer where more than one designer is working, or it is reasonably foreseeable that more than one designer will work, on a project. This should be considered separately from the test for appointing a Principal Designer under CDM 2015.
What happens if a domestic client does not appoint a CDM Principal Designer?
CDM 2015 contains provisions for domestic clients. Where the appointments required for a multi-contractor project have not been made, the designer in control of the pre-construction phase takes the Principal Designer role and the contractor controlling the construction phase takes the Principal Contractor role. It is nevertheless much clearer to establish responsibilities before work progresses.
Next steps & useful guides
If you are preparing a residential building project, these related PME guides will help you understand the wider approval and compliance process:
- Understand the overall Building Regulations process for homeowners
- Read our detailed guide to the Building Regulations design dutyholder role
- See what is involved when making a Building Regulations application
- Understand the role of Building Control during construction
- Learn how the Approved Documents support Building Regulations compliance
- See what information is normally included in technical Building Regulations plans
- Find out which certificates and project records you should keep
- Main legislation Construction (Design and Management) Regulations 2015 – usually called CDM 2015.
- When the role is required Where more than one contractor is, or is reasonably foreseeable to be, involved in the project.
- Main responsibility Plan, manage, monitor and co-ordinate health and safety during the pre-construction phase.
- Who can perform it? A suitable individual or organisation that is a designer, can control the pre-construction phase and has the competence and capability required for the project.
- Domestic homeowners Domestic projects are covered by CDM 2015, although special provisions determine how certain client duties are carried out.
- CDM vs Building Regulations They are separate regulatory roles. CDM focuses on health and safety; the Building Regulations role in England focuses on design compliance with Building Regulations.
- Same person for both roles? Potentially, provided that person or organisation is suitable and competent for each role and the required appointments are made clearly.
Planning a home extension or renovation? Ask Plans Made Easy which design and compliance responsibilities may apply to your project.
Official guidance and further reading
CDM and Building Regulations duties are legal requirements, so it is sensible to check the current official guidance for your project:
- Health and Safety Executive – official CDM 2015 guidance
- UK legislation – Construction (Design and Management) Regulations 2015
- GOV.UK – Building Regulations dutyholder and competence guidance
- Planning Portal – national planning and Building Regulations guidance
Ready to move your project forward?
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