CDM stands for Construction (Design and Management). The CDM Regulations 2015 are the main UK health and safety regulations for construction projects. They apply to all construction work and set out duties for everyone involved — from clients and designers to contractors and workers.
What's your role in the construction project?
Let's point you to the most relevant information.
What is CDM?
CDM stands for Construction (Design and Management). The CDM Regulations 2015 are the primary health and safety regulations for construction projects in the UK.
The regulations aim to:
- Integrate health and safety into the project from the start, not as an afterthought
- Define clear roles and responsibilities for everyone involved in construction work
- Improve planning and management to reduce accidents, injuries, and ill health
- Ensure information flows between all parties throughout the project lifecycle and beyond
CDM isn't just about big construction sites. The regulations apply to all construction projects, regardless of size or duration. Even small maintenance jobs are covered, though the level of compliance required is proportionate to the risk.
What counts as construction work?
The CDM Regulations apply to all construction work. This is broader than you might think.
Construction work includes:
- Building, altering, converting, fitting out, commissioning, renovating, repairing, upkeep, redecoration, decommissioning, demolition, or dismantling structures
- Installing, commissioning, maintenance, repair, or removal of mechanical, electrical, gas, compressed air, hydraulic, telecommunications, computer, or similar services
- Cleaning windows or facades that involves working at height or using water fed poles
- Removal of asbestos
- Temporary works (scaffolding, shoring, falsework)
- Site clearance and earthworks
- Painting and decorating when part of a construction project
- Installation of systems (heating, ventilation, fire detection, etc.)
NOT usually construction work:
- Routine maintenance by permanent staff (though health and safety planning is still needed)
- Cleaning work that doesn't involve work at height or specialist access equipment
- Tree surgery
- Archaeology
- Delivering materials to site (unless also installing them)
If you're commissioning work that involves structural alterations, working at height, services installation, or anything beyond simple maintenance, CDM almost certainly applies.
The five CDM duty holders
The CDM Regulations define five key roles with specific duties:
1. Client
The person or organisation commissioning the construction work.
Key duties:
- Make suitable arrangements for managing the project
- Appoint competent designers and contractors
- Ensure sufficient time and resources are allocated
- Provide pre-construction information to designers and contractors
- Ensure the Principal Designer and Principal Contractor carry out their duties
- Ensure a Construction Phase Plan is in place before work starts
- Ensure the Health and Safety File is prepared and retained
Clients can't delegate or transfer their CDM duties. Even if you appoint a project manager or agent, you remain legally responsible for ensuring your CDM duties are fulfilled.
2. Principal Designer
The designer appointed by the client on notifiable projects to control the pre-construction phase of the project.
Key duties:
- Plan, manage, monitor, and coordinate health and safety in the pre-construction phase
- Help and advise the client in bringing together pre-construction information
- Identify, eliminate, or control foreseeable risks
- Ensure designers carry out their duties
- Prepare and provide relevant information to other duty holders
- Liaise with the Principal Contractor for the smooth handover of information
- Prepare the Health and Safety File
The Principal Designer is usually an organisation or individual in the design team (architect, structural engineer, etc.) with knowledge of the project and design process.
3. Designer
Any individual or organisation that prepares or modifies designs for the construction project.
Designers include architects, engineers, surveyors, interior designers, and even contractors when they design temporary works.
Key duties:
- Eliminate foreseeable risks to health and safety so far as reasonably practicable
- Reduce risks that cannot be eliminated
- Provide design information about remaining risks
- Consider buildability, maintenance, and eventual demolition
- Cooperate with other designers and duty holders
- Communicate design decisions and their health and safety implications
Good design decisions can eliminate risks entirely. For example, specifying materials that don't require cutting at height, designing permanent edge protection, or choosing systems that reduce manual handling.
4. Principal Contractor
The contractor appointed by the client on notifiable projects to control the construction phase.
Key duties:
- Plan, manage, monitor, and coordinate the construction phase
- Liaise with the Principal Designer for the duration of the project
- Prepare the Construction Phase Plan before the construction phase begins
- Organise cooperation between contractors
- Ensure suitable site inductions are provided
- Prevent unauthorised access to the site
- Ensure welfare facilities are provided
- Ensure workers have necessary information, instruction, and training
- Consult and engage with workers
The Principal Contractor is typically the main or lead contractor on site.
5. Contractor
Any individual or organisation that carries out, manages, or controls construction work.
This includes main contractors, sub-contractors, self-employed tradespeople, and anyone who directly employs or engages construction workers.
Key duties:
- Plan, manage, and monitor construction work under their control
- Ensure workers under their control have necessary skills, knowledge, training, and experience
- Ensure welfare facilities are available
- Provide information about risks and how they will be controlled
- Comply with the Construction Phase Plan
- Cooperate with other duty holders
- Report obvious risks they become aware of
Principal Designer vs Principal Contractor
Principal Designer
- •Pre-construction phase leadership
- •Coordinates designers
- •Manages design-related health and safety
- •Prepares pre-construction information
- •Creates the Health and Safety File
- •Appointed only on notifiable projects
Principal Contractor
- •Construction phase leadership
- •Coordinates contractors on site
- •Manages on-site health and safety
- •Prepares Construction Phase Plan
- •Updates the Health and Safety File
- •Appointed only on notifiable projects
Bottom line: Both roles are only required on notifiable projects. On smaller projects, these coordinating duties still need to be managed, but formal appointments aren't required.
When does CDM apply?
CDM applies to all construction projects.
However, the specific duties depend on:
- Whether the client is commercial or domestic
- Whether the project is notifiable
Commercial vs Domestic Clients
Commercial client: A business or organisation carrying out a trade, business, or undertaking (whether for profit or not).
Examples: companies, public sector organisations, charities, partnerships, sole traders commissioning work on business premises.
Commercial clients have full CDM duties.
Domestic client: A person who commissions work on their own home (or the home of a family member) where the home is not used for business purposes.
Examples: homeowners having an extension built, loft conversion, new kitchen.
Most CDM client duties are automatically transferred to:
- The contractor (on non-notifiable projects)
- The Principal Designer or Principal Contractor (on notifiable projects)
However, domestic clients still need to appoint competent contractors and check basic arrangements are in place.
Landlords are NOT domestic clients when commissioning work on rental properties. If you're a landlord, you're a commercial client with full CDM duties, even for residential properties.
Notifiable Projects
A project is notifiable if the construction work is expected to:
- Last more than 30 working days and involve more than 20 workers at any point, OR
- Exceed 500 person days of work (e.g., 10 workers for 50 days)
If a project is notifiable, the client must:
- Notify the Health and Safety Executive (HSE) using form F10 before construction work starts
- Appoint a Principal Designer
- Appoint a Principal Contractor
- Display the F10 notice on site
If a project is not notifiable:
- F10 notification is not required
- Principal Designer and Principal Contractor appointments are not required
- But the work still needs to be planned and managed safely, and other CDM duties still apply
Notifiable Project Key Milestones
Client checks competence of designers and contractors before appointing them
Appoint Principal Designer to coordinate pre-construction phase
Notify HSE at least 2 weeks before construction phase begins
Appoint Principal Contractor to manage construction phase
Principal Contractor prepares plan; client ensures it's in place before work starts
Principal Designer creates and maintains; handed to client at project end
The F10 Notification
The F10 is a notification form sent to the HSE for notifiable projects.
When to submit: At least 2 weeks before the construction phase begins (or as soon as possible if the timescale makes that impractical).
Who submits it: The client. (Though in practice, the Principal Designer or Principal Contractor often submits it on behalf of the client.)
What information is required:
- Project details (address, description, start date)
- Client details
- Principal Designer details
- Principal Contractor details
- Approximate timescales and number of workers
- Declaration signed by or on behalf of the client
How to submit: Online via the HSE website or by post.
Construction work must not start until the HSE has been notified. Starting work on a notifiable project without notification is a breach of CDM and can result in enforcement action.
Construction Phase Plan
The Construction Phase Plan (CPP) is a key document that sets out how health and safety will be managed during construction.
Who prepares it:
- On notifiable projects: the Principal Contractor
- On non-notifiable projects: the contractor
When: Before construction work starts. The client must ensure a suitable plan is in place before allowing construction to begin.
What it should include:
- Description of the project and programme
- Management arrangements (who does what)
- Health and safety aims and how they'll be achieved
- Arrangements for controlling significant risks (method statements, permits to work)
- Site rules
- How health and safety information will be communicated
- Arrangements for consulting workers
- Welfare facilities
- Emergency procedures
- Details of any specific risks and how they'll be managed
The Construction Phase Plan should be proportionate to the project. For a simple, low-risk job, a few pages may be adequate. For complex, high-risk work, it needs to be comprehensive.
The Construction Phase Plan is a live document. It should be reviewed and updated throughout the project as circumstances change.
Health and Safety File
The Health and Safety File is a record of information for the client that focuses on health and safety. It should contain information needed to allow future construction work (maintenance, refurbishment, demolition) to be carried out safely.
Who prepares it:
- The Principal Designer (or designer on non-notifiable projects without a Principal Designer)
When: Starts during design and is added to throughout the project. Handed to the client at the end of the project.
What it should include:
- Brief description of the work carried out
- Significant residual risks and how they should be managed
- Key structural principles and details
- Hazardous materials (asbestos, lead, specialist coatings)
- Removal or dismantling information
- Information about plant and equipment (lifting equipment, cleaning systems, etc.)
- Health and safety information in design drawings, specifications, surveys
- Information about the structure, services, and materials that will be needed for future work
What it should NOT include:
- Construction Phase Plans (unless relevant to future work)
- Pre-construction information (unless relevant to future work)
- Routine maintenance information that poses no specific health and safety risks
- General project management information
Client's duty: The client must keep the Health and Safety File available for anyone who needs it for future construction work on the structure. If the property is sold, the file should be passed to the new owner.
Developer fined £200,000 for CDM failures
A property developer undertook a major residential conversion project. HSE inspectors found multiple CDM breaches during and after the project.
- ✗No Principal Designer appointed despite project being notifiable
- ✗HSE not notified (no F10 submitted)
- ✗No Construction Phase Plan in place when work started
- ✗Inadequate welfare facilities for workers
- ✗No Health and Safety File prepared
- ✗Poor control of work at height and structural work
The developer was prosecuted and fined £200,000 plus £50,000 costs. HSE issued a prohibition notice stopping work until arrangements improved.
CDM duties apply to all projects regardless of the client's familiarity with construction. Appointing the right people early and ensuring proper planning prevents both safety risks and legal consequences.
Key duties summary for each role
Client duties checklist
- Make suitable arrangements for managing the project
- Check competence and resources of all appointees
- Appoint Principal Designer and Principal Contractor (if project is notifiable)
- Submit F10 notification (if project is notifiable)
- Provide pre-construction information to designers and contractors
- Ensure Construction Phase Plan is in place before work starts
- Ensure adequate welfare facilities will be provided
- Ensure suitable management arrangements are maintained throughout
- Receive and keep the Health and Safety File
- Allow sufficient time and resources for all stages of the project
Principal Designer duties checklist
- Plan, manage, and monitor health and safety in the pre-construction phase
- Coordinate designers and ensure they fulfil their duties
- Help client gather and provide pre-construction information
- Identify, eliminate, or control foreseeable risks in design
- Ensure design information includes health and safety risks that can't be eliminated
- Liaise with Principal Contractor throughout the project
- Prepare Health and Safety File
- Provide information to Principal Contractor for Construction Phase Plan
Designer duties checklist
- Eliminate foreseeable risks in design so far as reasonably practicable
- Reduce risks that cannot be eliminated
- Design to avoid risks during construction, maintenance, and use
- Provide information about remaining risks
- Coordinate with other designers
- Cooperate with Principal Designer (if appointed)
- Check client is aware of their duties
Principal Contractor duties checklist
- Plan, manage, monitor, and coordinate construction phase
- Liaise with Principal Designer
- Prepare Construction Phase Plan before construction starts
- Keep Construction Phase Plan updated
- Organise cooperation between contractors
- Coordinate implementation of construction health and safety standards
- Ensure suitable site inductions
- Provide welfare facilities
- Prevent unauthorised site access
- Display F10 notice on site
- Provide relevant parts of Health and Safety File information to contractors
- Consult and engage with workers
Contractor duties checklist
- Plan, manage, and monitor work under your control
- Check own competence and that of workers
- Ensure workers have site induction
- Provide information, instruction, and training to workers
- Not start work unless Construction Phase Plan is in place
- Comply with Construction Phase Plan
- Comply with Principal Contractor's site rules
- Inform Principal Contractor of problems with plan or risks identified
- Provide welfare facilities (if no Principal Contractor)
- Cooperate with other duty holders
Even if you're not required to formally appoint a Principal Designer or Principal Contractor, someone still needs to carry out the planning, coordination, and management tasks. On smaller projects, the designer or main contractor often fulfils these functions informally.
Common CDM mistakes to avoid
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Assuming CDM doesn't apply to small projects — All construction work is covered by CDM. The requirements are proportionate to the risks, but they still apply.
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Appointing someone who doesn't understand their role — Competence is key. Duty holders need to understand what their CDM role requires.
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Not notifying the HSE when required — If your project is notifiable, the F10 must be submitted before work starts.
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Starting work without a Construction Phase Plan — Clients must not allow construction to start until a suitable plan is in place.
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Treating the Health and Safety File as a box-ticking exercise — It should be a useful record for future work, not a dumping ground for all project paperwork.
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Failing to allow adequate time — Health and safety planning takes time. Rushing design or construction increases risks.
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Not providing pre-construction information — Designers and contractors need to know about existing risks (asbestos, ground conditions, existing services, etc.).
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Ignoring ongoing duties — CDM isn't just about initial appointments. Duty holders have ongoing responsibilities throughout the project.
Frequently asked questions
Yes. CDM applies to all construction projects, regardless of size or duration. However, the level of compliance is proportionate to the risk. Small, simple projects have less onerous requirements than large, complex ones. Notifiable projects (over 30 days or 500 person days) have additional duties including appointing a Principal Designer and Principal Contractor.
The client is responsible for ensuring adequate resources (including time and money) are available. CDM compliance costs should be factored into the project budget from the start. Designers, contractors, and coordinators include their CDM work in their fees.
No. The same organisation cannot be both Principal Designer and Principal Contractor. This is to maintain the separation between design coordination and construction coordination. However, an organisation can be a designer and a contractor on the same project, just not both principal roles.
On notifiable projects, if the client fails to appoint a Principal Designer, the role automatically defaults to the client. This means the client takes on all Principal Designer duties, which is rarely practical. The same applies for Principal Contractor.
The client must keep the Health and Safety File for as long as they own or control the structure. If the property is sold or transferred, the file should be passed to the new owner. It's needed for any future construction work on the building.
Failure to comply with CDM Regulations is a criminal offence. The HSE can issue improvement notices, prohibition notices, and prosecute. Penalties include unlimited fines and up to 2 years imprisonment for serious breaches. Directors and senior managers can be personally prosecuted under the Health and Safety at Work Act.
No. The role of CDM Coordinator was abolished when the 2015 regulations came into force. It was replaced by the Principal Designer role, which has a broader remit and more clearly defined duties.
Technically, a domestic client's duties are transferred to the Principal Designer or Principal Contractor. However, it's not practical or advisable for a homeowner to take on these specialist roles. It's better to ensure competent professionals are appointed to fulfil these duties.
Next steps
Not sure whether your project needs CDM appointments or F10 notification?
Want to understand what a Principal Designer actually does day-to-day?
Principal Designer duties explained →
Unsure who should be appointed as Principal Designer or Principal Contractor? A CDM specialist can review your project and advise on competence, appointments, and your specific duties.
Related articles:
- HSG150: Complete Guide to Construction Safety — The HSE's essential construction guidance explained
- Do I need CDM appointments?
- Principal Designer duties
- Construction Phase Plan explained
HSE guidance:
- HSG150 HSE Reference — Official HSE document summary
Useful tools: