Guide
Appoint a Principal Contractor
How to appoint a Principal Contractor under CDM 2015. Covers when appointment is required, who can be appointed, competence requirements, making the appointment in writing, and what happens if you fail to appoint.
If your construction project involves more than one contractor, you must appoint a Principal Contractor before construction work begins. This is a legal duty under the Construction (Design and Management) Regulations 2015 (CDM 2015).
The Principal Contractor takes responsibility for planning, managing, and monitoring health and safety during the construction phase. Without this appointment, you as the client assume all Principal Contractor duties yourself - a significant legal and practical burden.
This guide explains when you must appoint, who can be appointed, how to check competence, and what the appointment should contain.
When you must appoint a Principal Contractor
You must appoint a Principal Contractor when:
- Your project involves more than one contractor, or
- It is reasonably foreseeable that more than one contractor will work on the project at any time
The 'more than one contractor' test applies whether contractors work simultaneously or at different times during the project. If an electrician finishes work in week one and a plumber arrives in week three, you still need a Principal Contractor.
Example scenarios requiring Principal Contractor appointment:
- Office refurbishment with separate contractors for M&E, joinery, and decoration
- New build with main contractor and specialist subcontractors
- Extension project using a builder, roofer, and window installer
- Demolition and rebuild using different specialist firms
When Principal Contractor is NOT required:
- Single contractor project with no subcontractors
- Single contractor using only their own employees (no other contractors)
When to make the appointment
You must appoint the Principal Contractor:
- As soon as practicable after you know you will need one, AND
- In any event before the construction phase begins
In practice, this means appointing the Principal Contractor as part of your procurement process, well before any work starts on site. Early appointment allows the Principal Contractor to:
- Input into the project programme
- Liaise with the Principal Designer
- Plan site logistics and welfare provision
- Prepare the construction phase plan before work starts
Critical point: Construction work must not begin until the Principal Contractor has been appointed and the construction phase plan is in place.
Who can be a Principal Contractor
The Principal Contractor must be:
- A contractor (not a designer, consultant, or the client themselves unless they carry out construction work)
- An organisation or individual with the skills, knowledge, training, experience, and organisational capability to fulfil the role
Typically, the Principal Contractor is:
- The main contractor with overall responsibility for site management
- A construction management firm directly managing the works
- In design-and-build contracts, the design-build contractor
A client can appoint themselves as Principal Contractor only if they are genuinely carrying out construction work and have the competence to fulfil the role. This is unusual in practice.
Organisational capability
Beyond individual skills, the Principal Contractor needs organisational capability to manage health and safety across multiple contractors. Consider whether they have:
- Sufficient staff to plan, manage, and monitor the construction phase
- Experience managing projects of similar size and complexity
- Adequate resources (time, people, systems) allocated to this project
- A health and safety management system appropriate to their activities
What the Principal Contractor must do
Once appointed, the Principal Contractor has specific duties under Regulation 13 of CDM 2015. Understanding these helps you assess competence and set clear expectations.
Key responsibilities in practice
Plan, manage, and monitor the construction phase: The Principal Contractor must ensure work is organised so it can proceed safely. This includes sequencing activities, managing interfaces between contractors, and ensuring adequate time is allowed.
Prepare and maintain the construction phase plan: Before construction starts, the Principal Contractor must prepare a written plan setting out how health and safety will be managed. This must be reviewed and updated throughout the project.
Coordinate contractors: The Principal Contractor ensures all contractors cooperate with each other, follow site rules, and implement their parts of the construction phase plan.
Site induction: Everyone working on site must receive a suitable site-specific induction before starting work. The Principal Contractor provides or coordinates this.
Site security: The Principal Contractor must take steps to prevent unauthorised access to the site.
Welfare facilities: Adequate toilets, washing facilities, drinking water, rest areas, and changing facilities must be provided throughout the construction phase.
Worker consultation: The Principal Contractor must consult workers or their representatives on health, safety, and welfare matters.
Liaise with Principal Designer: Throughout the project, the Principal Contractor maintains communication with the Principal Designer, sharing relevant information about planning and coordination.
How to check competence
Before appointing a Principal Contractor, you must take reasonable steps to satisfy yourself they have the skills, knowledge, training, experience, and organisational capability to fulfil the role.
This is not about ticking boxes. It means genuinely assessing whether this contractor can manage health and safety on this specific project.
-
Review their health and safety policy
Ask for their written health and safety policy. Does it cover the activities relevant to your project? Is it proportionate to their size and the work they do? A generic downloaded policy is a warning sign.
-
Check relevant experience
Ask for evidence of managing similar projects - similar scale, complexity, and type of work. Request project references and case studies. An excellent track record on small domestic works does not prove competence for a multi-million pound commercial project.
-
Assess key personnel
Who will actually manage health and safety on your project? What are their qualifications and experience? A site manager with SMSTS (Site Management Safety Training Scheme) certification is a typical minimum. For complex projects, consider whether they need additional specialist expertise.
-
Review their systems and procedures
How do they manage subcontractors? What site induction do they provide? How do they monitor compliance? How do they manage changes? Ask for examples from previous projects.
-
Check their track record
Ask about accidents, near misses, and enforcement action on recent projects. Check HSE's public register of prosecutions. Consider their insurance claims history. A pattern of incidents suggests systemic problems.
-
Consider industry accreditation
Membership of schemes like CHAS, SafeContractor, Constructionline, or SSIP-approved schemes provides some assurance of baseline competence. But accreditation alone is not sufficient - it shows minimum standards, not project-specific capability.
-
Ask about resources
Will they have adequate staff, time, and budget to manage health and safety on your project? An overstretched contractor cutting corners is a compliance risk.
Proportionate assessment: The depth of competence checking should match the project's risk and complexity. A straightforward office fit-out needs less investigation than a complex demolition or work in a high-risk environment.
Document your assessment: Keep records of what you asked for, what you received, and your conclusions. If something goes wrong, you may need to demonstrate you took reasonable steps.
Making the appointment
The Principal Contractor appointment must be made in writing. A verbal agreement is not sufficient and does not transfer the duties.
What the appointment should include
The written appointment should clearly state:
- The name of the person or organisation being appointed as Principal Contractor
- The project to which the appointment relates
- Confirmation they are accepting the role and its duties under CDM 2015
- The date the appointment takes effect
- Resources allocated (time, staff, budget for health and safety)
Forms of written appointment
The appointment can be made through:
- A clause in the main construction contract
- A separate appointment letter countersigned by the contractor
- A formal CDM appointment document
Many standard construction contracts (JCT, NEC) include provisions for CDM appointments. Ensure these are completed correctly.
Accepting the appointment
The contractor must accept the appointment. Unilateral appointment without acceptance is not effective. Ensure you receive written confirmation that they accept the Principal Contractor role.
Notification to HSE
If your project is notifiable (exceeds certain thresholds), you must include Principal Contractor details in the F10 notification to HSE.
The F10 notification requires Principal Contractor contact details. If you have not yet appointed at the time of notification, you must update the notification once the appointment is made.
The notification (or HSE acknowledgement) must be displayed on site where workers can read it.
If you do not appoint a Principal Contractor
If you fail to appoint a Principal Contractor when one is required, you assume all Principal Contractor duties yourself.
This means you become legally responsible for:
- Planning, managing, and monitoring the construction phase
- Preparing the construction phase plan
- Coordinating all contractors
- Providing site induction
- Ensuring welfare facilities
- Preventing unauthorised access
- Consulting workers
- Liaising with the Principal Designer
For most commercial clients, this is impractical. These duties require construction industry expertise and a site presence. Failing to make an appointment does not remove the duties - it transfers them to you, with all the legal liability that entails.
Enforcement consequence: If you assume Principal Contractor duties by default and fail to fulfil them, you can be prosecuted. HSE will not accept "I didn't know I was the Principal Contractor" as a defence.
Domestic clients
If you are a domestic client (commissioning work on your own home for personal use, not business purposes), different rules apply.
Domestic clients do not have a duty to formally appoint a Principal Contractor. Instead, the duties transfer automatically:
- Multiple contractors: The contractor in control of the construction phase becomes the Principal Contractor by default
- Single contractor: That contractor assumes client duties
Alternatively, a domestic client can enter a written agreement with the Principal Designer to transfer client duties to them.
Who counts as domestic? Only individuals commissioning work on their own home for their own use. Landlords commissioning work on rental properties are commercial clients. Property developers building homes to sell are commercial clients.
Coordination with Principal Designer
The Principal Contractor works alongside the Principal Designer throughout the project. Good coordination between these roles is essential for effective health and safety management.
Information flow
The Principal Designer provides:
- Pre-construction information relevant to the construction phase
- Design risk information and residual risks from design decisions
- Information to assist preparation of the construction phase plan
The Principal Contractor provides:
- Information about how construction will be carried out
- Details of sequence and methods that affect design
- Information for the health and safety file (as-built information, operation and maintenance requirements)
Handover
If the Principal Designer's appointment ends before the construction phase is complete, they must pass the health and safety file to the Principal Contractor. The Principal Contractor then continues updating it and hands it to the client at project completion.
Common mistakes to avoid
Late appointment: Appointing the Principal Contractor after construction has started is a breach. Make the appointment during procurement, before any work begins on site.
Verbal agreement only: A handshake or verbal understanding is not an appointment. It must be in writing.
Appointing without checking competence: You must take reasonable steps to assess competence. Appointing the cheapest bidder without investigation is a breach.
Assuming main contractor is automatically Principal Contractor: The appointment must be explicit. Simply contracting with a main contractor does not make them Principal Contractor unless the contract or separate appointment document states this clearly.
Appointing someone who is not a contractor: The Principal Contractor must be a contractor. Appointing a project manager, consultant, or design firm that does not carry out construction work is invalid.
Not giving adequate resources: If you appoint but then refuse to allocate adequate time, budget, or authority to fulfil the role, you may share liability for failures.
Related guidance
Appointing a Principal Contractor is one part of your CDM duties. Also read:
- CDM client duties - Your overall responsibilities as a construction client
- Appoint a Principal Designer - The parallel appointment for design coordination
- Construction phase plan - What the Principal Contractor must prepare
- Pre-construction information - Information you must provide to duty holders
- F10 notification - When and how to notify HSE of your project