Are you planning or undertaking construction work?
Quick check to understand your CDM duties
Why CDM matters
Construction is one of the UK's most dangerous industries. Every year, dozens of workers are killed and thousands seriously injured in preventable accidents. Many of these stem from failures in planning, coordination, and risk management.
The Construction (Design and Management) Regulations 2015 exist to ensure health and safety is considered from the earliest design stages through to demolition. When applied properly, CDM saves lives.
CDM 2015 applies to all construction projects in Great Britain. It places legal duties on everyone involved — from clients who commission work, through designers and principal designers, to contractors who carry it out. Ignoring these duties can result in prosecution, unlimited fines, and imprisonment.
What is construction work?
CDM applies to all construction work, which includes:
- Building, alteration, conversion, fitting out, commissioning, renovation, repair, maintenance, redecoration, or demolition of a structure
- Installation, commissioning, maintenance, or removal of mechanical, electrical, gas, compressed air, hydraulic, telecommunications, computer, or similar services
- Site clearance, groundworks, excavation, tunnelling, laying foundations
- Assembly or disassembly of prefabricated elements
- Removal of structures or waste resulting from construction work
Even minor works can be construction work. Installing air conditioning, rewiring an office, replacing a roof, or repainting a building all count. The key question is whether the work involves construction activities, not the size of the project.
Domestic vs non-domestic projects
CDM does not apply to construction work carried out for a domestic client on their own home where they live or will live. This exemption covers:
- Work on your own house or flat
- Converting a property you intend to live in
- Extensions, loft conversions, renovations for personal use
CDM does apply to:
- Work on buy-to-let properties
- Property development for sale or rent
- Landlord repairs and maintenance on rental properties
- Work on commercial premises
- Work for housing associations or local authorities
If you're a domestic client but the project is notifiable (over 30 days or 500 person days), HSE recommends appointing a Principal Designer and Principal Contractor anyway to manage health and safety effectively.
The five CDM duty holders
CDM 2015 creates five key duty holder roles. Understanding who does what is essential for compliance.
1. The Client
Who: The person or organisation for whom the construction project is carried out. If you're commissioning the work, you're the client.
Key duties:
- Make suitable arrangements for managing the project
- Appoint a Principal Designer and Principal Contractor (if more than one contractor)
- Ensure appointed duty holders are competent and adequately resourced
- Provide pre-construction information
- Ensure the Principal Designer prepares a health and safety file
- Ensure welfare facilities are provided
- Allow sufficient time and resources for each stage
When duties apply: From project conception through to handover.
2. The Principal Designer
Who: A designer (organisation or individual) appointed by the client to plan, manage, monitor and coordinate health and safety in the pre-construction phase. Must have the skills, knowledge, and experience to fulfil the role.
Key duties:
- Plan, manage, and monitor pre-construction health and safety
- Coordinate designers' work to eliminate or reduce foreseeable risks
- Identify, eliminate or control foreseeable risks
- Ensure designers comply with their duties
- Prepare and provide pre-construction information to the Principal Contractor
- Liaise with the Principal Contractor to coordinate construction phase planning
- Prepare the health and safety file
When appointed: As soon as practicable after the client knows enough about the project to appoint someone. Ideally before any design work begins.
The Principal Designer doesn't need to be a "designer" in the traditional sense. Any competent organisation or individual can be appointed, but they must have the technical knowledge and experience to coordinate health and safety during design.
3. Designers
Who: Anyone who prepares or modifies designs for a building, product or system relating to construction work — including architects, engineers, surveyors, and anyone specifying materials or products.
Key duties:
- Eliminate foreseeable risks to health and safety through design decisions
- Reduce or control risks that cannot be eliminated
- Provide information about remaining risks
- Ensure designs include adequate information about health and safety
- Cooperate with the Principal Designer and other designers
When duties apply: Whenever you prepare or modify a design.
4. The Principal Contractor
Who: A contractor appointed by the client to plan, manage, monitor and coordinate the construction phase of a project where it involves more than one contractor.
Key duties:
- Plan, manage, monitor and coordinate the entire construction phase
- Liaise with the Principal Designer for the duration of the project
- Prepare the construction phase plan before construction begins
- Organise cooperation between contractors and coordinate their work
- Ensure suitable site inductions are provided
- Prevent unauthorised access to the site
- Ensure welfare facilities are provided and maintained
- Consult and engage with workers about health and safety
When appointed: Before construction work starts.
5. Contractors
Who: Anyone who directly employs or engages construction workers or manages construction work. This includes sub-contractors, sole traders, and the self-employed.
Key duties:
- Plan, manage and monitor construction work under their control
- Ensure workers are competent and properly supervised
- Ensure workers have site inductions
- Provide appropriate information and training
- Ensure welfare facilities are available
- Comply with the construction phase plan and any site rules
- Report accidents, injuries and dangerous occurrences
When duties apply: During the construction phase.
CDM Duty Holders at a Glance
| Duty Holder | When Appointed | Primary Focus |
|---|---|---|
| Client | Throughout project | Appoint competent duty holders, provide resources and time |
| Principal Designer | Pre-construction phase | Coordinate designers, prepare health and safety file |
| Designer | When designing | Eliminate or reduce risks through design |
| Principal Contractor | Construction phase | Plan, manage and coordinate work on site |
| Contractor | During their work | Ensure safe execution of their work package |
All projects have a client and contractors. Principal Designer and Principal Contractor are only required where there is more than one contractor.
Client duties explained
The client role is critical. Even if you have no construction knowledge, you cannot delegate your client duties — though you can appoint advisors to help you comply.
Early appointments matter
The single biggest mistake clients make is appointing the Principal Designer too late. Appoint them as soon as you know enough about the project — ideally before any design work starts. Late appointment means design risks are already locked in.
Making suitable arrangements
You must make and maintain arrangements for managing the project, including:
- Appointing the right people at the right time
- Ensuring there is enough time and resources for each stage
- Making sure duty holders have the information they need
- Ensuring the Principal Designer prepares a health and safety file
- Ensuring welfare facilities are in place before work starts
Checking competence
You must ensure appointed duty holders are competent and adequately resourced. This means:
- Checking they have the skills, knowledge, experience and organisational capability
- Ensuring they allocate sufficient resources (time, money, people)
- Asking about their approach to health and safety management
- Requesting evidence of previous similar projects
You cannot rely solely on accreditations or memberships. You must satisfy yourself that the specific individuals or organisations are competent for your project.
Pre-construction information
You must provide pre-construction information to designers and contractors as soon as practicable. This includes:
- Information about the site (ground conditions, existing structures, buried services)
- Previous health and safety files
- Any known health hazards (asbestos, contamination)
- Existing drawings, surveys, and structural information
- Proposed construction methods or sequence
- Client requirements and timescales
Notifiable projects and the F10
Some projects must be notified to the HSE before work begins. A project is notifiable if the construction phase will:
- Last longer than 30 working days and involve more than 20 workers working simultaneously at any point, or
- Exceed 500 person days of work (e.g., 50 workers for 10 days = 500 person days)
The F10 notification
For notifiable projects, the client (or the Principal Designer on the client's behalf) must send an F10 notification to HSE before construction work starts. The notification must include:
- Project details and location
- Client, Principal Designer and Principal Contractor contact details
- Planned start and end dates
- Estimated maximum number of people working on site
- Number of contractors expected
Failure to notify when required is a criminal offence. Submit the F10 as soon as the Principal Contractor is appointed, but no later than the start of the construction phase.
The notification can be submitted online via the HSE website. You'll receive a confirmation and must display this on site.
The Construction Phase Plan
The Principal Contractor must prepare a construction phase plan before the construction phase begins. The plan must set out the health and safety arrangements and site rules which will ensure that the construction phase is planned, managed, monitored and coordinated.
What goes in the plan
The construction phase plan should be proportionate to the project and include:
- Description of the project and programme
- Management arrangements and site rules
- Arrangements for controlling significant risks
- Arrangements for site induction, training and communication
- Welfare facilities
- Emergency procedures
- Arrangements for consulting workers
- Site security arrangements
The plan is a living document — it must be reviewed and updated as the project progresses and as new risks emerge.
For smaller, straightforward projects, the plan can be brief. For complex projects, it will be substantial. The key test is whether it adequately addresses the risks and provides clear arrangements for managing them.
The Health and Safety File
The Principal Designer must prepare the health and safety file for the project. This is one of the most important — and most frequently neglected — CDM requirements.
What is the health and safety file?
The file contains information about the completed structure that will be needed to ensure health and safety during future maintenance, alteration, refurbishment, or demolition. It's not a dumping ground for every project document — it should contain only information relevant to future work.
What should be in it
- Brief description of the work carried out
- Residual hazards and how they should be managed
- Key structural principles and safe working loads
- Location of services, especially those that are concealed
- Information about materials used (e.g., asbestos surveys, fragile materials)
- Drawings and plans showing the as-built structure
- Details of equipment requiring maintenance and safe methods
- Manuals for building services and installed equipment
What should NOT be in it
- Detailed risk assessments or method statements (these are for construction, not future use)
- Pre-construction information (unless still relevant to future work)
- Contractual or financial documents
- Duplicate information already available elsewhere
Client's duty to keep the file
The client must ensure the file is kept available for inspection and handed over when the property is sold or leased. Failure to maintain the file is a breach of CDM.
The health and safety file must be handed over to the client at the end of the project. If you're the client, you must keep it for the lifetime of the structure and pass it to new owners if you sell.
CDM project stages and timeline
Typical CDM Project Flow
As soon as practicable after deciding to proceed
Coordinated by Principal Designer
Shared with Principal Contractor
Before construction phase begins
Before construction work starts
Before work on site begins
Throughout construction phase
Client must retain for life of structure
Common CDM compliance mistakes
1. Appointing duty holders too late
The Principal Designer should be appointed at project conception, not after designs are substantially complete. Late appointment defeats the purpose — design risks are already locked in.
2. Confusing CDM with method statements
CDM is about strategic health and safety management, not detailed work instructions. The Principal Designer coordinates design risks. The Principal Contractor manages site risks. Both are different from task-specific method statements.
3. Treating the health and safety file as a box-ticking exercise
A file stuffed with irrelevant documents is worse than useless. It should be a concise, accessible reference for future maintenance and alterations.
4. Not notifying when required
The 30-day and 500-person-day thresholds are easily exceeded. Plan ahead and submit the F10 early if in doubt.
5. Clients thinking they have no duties
Even if you hire professionals to manage the project, you remain the client under CDM. You cannot delegate your legal duties, only appoint others to help you fulfil them.
6. Assuming small projects are exempt
CDM applies to all construction projects except those for domestic clients on their own homes. Size doesn't matter — a two-day electrical rewire on a commercial property triggers full CDM duties.
Common questions
Yes. CDM 2015 applies to all construction projects, regardless of size, except work carried out for a domestic client on their own home. A one-day electrical installation in an office, a shop refit, or roof repairs on a rental property all trigger CDM duties. The duties are proportionate to the risk, but they still apply.
Only if there is more than one contractor. If you're using a single contractor who is doing all the work (including any design), they fulfil all contractor and designer duties. If you have multiple contractors at any point, you must appoint a Principal Designer and Principal Contractor.
When the project is notifiable: lasting more than 30 working days with more than 20 workers at any point, OR exceeding 500 person days. Submit the F10 before construction work starts. It can be submitted by the client or the Principal Designer on behalf of the client.
Yes, if the client has the necessary skills, knowledge, experience and organisational capability. Many experienced developers and construction-savvy property managers act as Principal Designer or even Principal Contractor. But you must be genuinely competent — it's not a way to avoid costs.
The construction phase plan is a high-level document prepared by the Principal Contractor setting out the overall health and safety arrangements and site rules for the project. Method statements are detailed work instructions prepared by individual contractors for specific high-risk tasks. The plan sets the framework; method statements provide the detail.
HSE can prosecute for breaches of CDM 2015. Penalties include unlimited fines and up to 2 years imprisonment. Even without prosecution, failure to comply can result in project delays, increased costs, prohibition notices stopping work, and significantly increased liability if an accident occurs.
Yes, if it's construction work (which most maintenance and repairs are) and it's not being done on a domestic client's own home. Planned maintenance, reactive repairs, painting, roofing, M&E servicing — all construction work. All subject to CDM if done on commercial premises or rental property.
The Principal Designer must prepare it. They gather information from designers and contractors throughout the project and compile it into a usable format. At project completion, they hand it to the client, who must keep it available for inspection and pass it on to future owners.
You still have duties under both roles. This is common for developers, landlords doing their own work, or property managers. You must still plan properly, manage risks, and (if the project is notifiable) submit an F10 and prepare a construction phase plan and health and safety file. You can't contract out of the law by doing the work yourself.
For the lifetime of the structure. If you sell or lease the building, you must hand the file to the new owner or tenant. If the building is demolished, the file should be given to whoever is carrying out the demolition (it contains vital safety information for them).
Real enforcement examples
Developer fined £800,000 after worker death
A developer was prosecuted after a worker fell through a fragile roof during a warehouse refurbishment. The project had not been notified and no Principal Designer or Principal Contractor had been appointed.
- ✗Project was notifiable but no F10 submitted
- ✗No Principal Designer appointed to coordinate design safety
- ✗No Principal Contractor appointed to manage site safety
- ✗Fragile roof risks not identified or controlled
- ✗No edge protection or working platform provided
- ✗Workers not informed of fragile roof hazards
The developer was fined £800,000 plus costs. Director received a suspended prison sentence. HSE stated the death was entirely preventable with proper CDM compliance.
CDM is not bureaucracy — it's a system for preventing deaths. Clients cannot ignore their duties. Failing to appoint competent duty holders and notify HSE when required can have fatal consequences.
Source: Based on HSE prosecution records
Principal Designer prosecuted for inadequate health and safety file
Following a serious injury during refurbishment work, HSE investigated and found the Principal Designer from the original project had failed to prepare an adequate health and safety file. Critical information about structural modifications and asbestos was missing.
- ✗Health and safety file contained generic documents, not project-specific information
- ✗Asbestos survey results not included in the file
- ✗Structural alterations not documented
- ✗No information about residual risks for future maintenance
- ✗File not handed to client at project completion
The Principal Designer (a design consultancy) was fined £200,000. The court found they had treated the file as a 'tick-box' exercise rather than a safety-critical document.
The health and safety file is not optional or cosmetic. It must contain information necessary to ensure safety during future work. Principal Designers must take this duty seriously — future workers' lives depend on it.
Source: Based on HSE prosecution records
Sector-specific guidance
CDM applies across all construction sectors. Here's how it typically applies in common scenarios:
CDM in Different Sectors
| Sector | Typical CDM Scenario | Key Considerations |
|---|---|---|
| Property Development | Multiple contractors, notifiable projects | Always appoint PD and PC. Early design coordination critical. |
| Landlords (Commercial) | Maintenance, refurbishment, fit-outs | You're the client. Must appoint PD/PC if multiple contractors. |
| Landlords (Residential) | Work on rental property or common areas | CDM applies (not domestic exemption). Often notifiable. |
| Facilities Management | Ongoing maintenance and projects | Each project assessed separately. May be client or contractor. |
| Retail/Hospitality Fit-Out | Shop fits, restaurant refurbs | Coordinating designers and trades critical. Often tight programmes. |
| Schools/Public Buildings | Extensions, refurbs, M&E upgrades | Managing risk to occupants key. Phased programmes common. |
This is general guidance. Each project must be assessed on its specific facts.
Related sectors and content
CDM intersects with many other health and safety responsibilities:
Construction Sector
Comprehensive guidance for construction businesses, including CDM, site safety, and welfare.
Builders
Practical guidance for builders on CDM contractor duties, site safety, and compliance.
Roofers
Working at height, fragile surfaces, and CDM compliance for roofing work.
Related content
- HSG150: Complete Guide to Construction Safety — The HSE's essential construction safety guidance explained
- Construction Safety Topic — Comprehensive guide to building site health and safety
- Asbestos Management — Often discovered during construction work. Must be managed under CDM and asbestos regulations.
- Workplace Safety — General health and safety duties that apply alongside CDM.
- Risk Assessment Fundamentals — The foundation of CDM planning and management.
Get started with CDM
Not sure where to begin? These resources can help:
HSE CDM Guidance (Official)
The Health and Safety Executive's comprehensive guidance on CDM 2015, including duty holder responsibilities and FAQs.
HSE Hierarchy of Risk Controls
Understanding how to eliminate and reduce risks through design — the core of CDM.
Need help understanding your CDM duties or ensuring compliance on your project? A CDM advisor or competent Principal Designer can guide you through your specific obligations and help you set up proper arrangements.
Disclaimer: This guidance is for general information only and does not constitute legal advice. CDM 2015 creates legal duties that vary depending on your specific project and role. For complex projects or if you're unsure about your duties, seek professional advice from a CDM consultant or health and safety professional. The law in this area is enforced by the Health and Safety Executive and breaches can result in prosecution.