The Construction (Design and Management) Regulations 2015 — known universally as CDM 2015 — are the UK's primary legal framework for managing health and safety throughout a construction project. They apply to virtually every construction project in the country, from a single tradesperson fitting a bathroom to a £500m infrastructure scheme. They impose criminal liability for non-compliance. And they are enforced by the Health and Safety Executive (HSE).
CDM 2015 is not just a site safety checklist. It is a framework that requires health and safety to be embedded from the earliest design decisions through to project completion — and beyond. It places duties on clients, designers, principal designers, principal contractors and contractors. Each dutyholder has specific, legally binding responsibilities that cannot be transferred away simply by appointing someone else.
For quantity surveyors, commercial managers and project managers, CDM matters because it directly affects procurement, programme, appointments, documentation and liability. Understanding who does what under CDM — and when — is core professional competence. It also appears regularly in RICS APC interviews.
This guide explains CDM 2015 in plain English: what it is, who it applies to, what each dutyholder must do, when HSE notification is required, and what documents you need to produce.
What Are the CDM Regulations 2015?
CDM 2015 stands for the Construction (Design and Management) Regulations 2015. They came into force on 6 April 2015, replacing CDM 2007. They are made under the Health and Safety at Work etc Act 1974 and are enforced by the HSE.
Their purpose, as Enevo sets out, is to 'make sure construction work is planned, designed, managed and carried out safely'. The regulations require that risk management begins at the design stage — not when workers arrive on site — and continues throughout the entire project lifecycle including maintenance, repair and eventual demolition.
CDM 2015 applies to construction work of all sizes. 'Construction work' is defined broadly and includes building, civil engineering, alteration, conversion, fitting out, renovation, repair, upkeep, redecoration, demolition, and the installation or removal of mechanical, electrical and other services. Most work done by contractors and subcontractors falls within this definition.
CDM duties are not optional and cannot be contracted out of. Failure to comply is a criminal offence under the Health and Safety at Work etc Act 1974, carrying the risk of prosecution, heavy fines and custodial sentences.
The Five CDM 2015 Dutyholders
CDM 2015 identifies five dutyholders — roles with specific, legally binding responsibilities. On many projects, one person or organisation may hold more than one role. On smaller projects, some roles may not apply. But the duties still exist; they just sit with whoever is carrying out that function.
Table 01 / CDM 2015 dutyholders
The Five Dutyholders and Their Core Responsibilities
| Dutyholder | When Required | Core Duties |
|---|---|---|
| Client | All projects | Make suitable arrangements, allocate time and budget, appoint competent PD and PC, ensure the CPP and H&S file are in place, and notify HSE where required. |
| Principal Designer (PD) | Projects with more than one contractor | Plan, manage and coordinate pre-construction health and safety. Prepare and update pre-construction information. Compile the H&S file. |
| Designer | All projects where design is produced | Eliminate or reduce design-stage hazards, provide pre-construction information and cooperate with the Principal Designer. |
| Principal Contractor (PC) | Projects with more than one contractor | Prepare and update the Construction Phase Plan, coordinate site health and safety, manage contractors, ensure welfare and consult workers. |
| Contractor | All projects | Plan, manage and monitor their own work, provide induction and training, comply with the CPP and establish suitable site arrangements. |
On smaller projects with one contractor, the PD and PC roles may not be required, but all other duties still apply. Domestic clients' duties normally transfer to the appointed contractor.
1. The Client
The client is the person or organisation commissioning the construction work. Complys notes that clients 'have the most fundamental duties under CDM 2015 because they set the timeframe, budget and project culture that determines whether safety is genuinely prioritised'.
Client duties include making suitable arrangements for managing the project, ensuring adequate time and resources are allocated, appointing a competent Principal Designer and Principal Contractor where required, ensuring the Construction Phase Plan is in place before work starts, and notifying the HSE where the project meets notification thresholds.
Domestic clients — individuals having work done on their own home — have reduced duties. In most cases, their CDM duties transfer automatically to the appointed contractor or Principal Contractor.
2. The Principal Designer (PD)
The Principal Designer role was introduced by CDM 2015 (replacing the CDM Coordinator from CDM 2007). The PD is appointed by the client on projects involving more than one contractor. Their role is to plan, manage, monitor and coordinate health and safety during the pre-construction phase — before any work starts on site.
Key PD duties: preparing and maintaining pre-construction information; identifying and eliminating design-stage hazards where possible; ensuring designers cooperate and communicate; and compiling the Health and Safety File at the end of the project. The PD must have the skills, knowledge and experience to carry out the role.
The PD is typically a design practice, architect or engineer — whoever has control over the pre-construction phase. On some projects, a specialist CDM consultant fulfils the PD role.
3. The Designer
A designer is anyone who prepares or modifies a design for construction work — architects, engineers, quantity surveyors preparing specifications, interior designers, landscape architects. Designers have a duty to eliminate or reduce foreseeable risks during the design process before passing residual risks to the Principal Designer and Principal Contractor.
Designers must not start work on a project unless the client is aware of their CDM duties, and must cooperate with the Principal Designer in coordinating health and safety during the pre-construction phase.
4. The Principal Contractor (PC)
The Principal Contractor is appointed by the client on projects with more than one contractor. They take overall responsibility for coordinating and managing health and safety during the construction phase.
PC duties include: preparing, maintaining and implementing the Construction Phase Plan; organising cooperation between contractors; providing inductions and training; ensuring welfare facilities are in place; consulting workers on health and safety; and maintaining a site where construction work can be done safely. The PC must not allow construction work to start unless the Construction Phase Plan contains adequate pre-construction information.
5. The Contractor
A contractor is any organisation or individual carrying out construction work. Every contractor on a project — including subcontractors — has CDM duties regardless of size or trade. Duties include planning, managing and monitoring their own work, ensuring workers have proper inductions and information, and complying with the Construction Phase Plan.
Contractors must not start construction work unless: the client is aware of their CDM duties; a Principal Contractor has been appointed (where required); and the Construction Phase Plan is in place. Enevo notes that 'the aim is not paperwork for its own sake — the aim is safer construction, safer buildings and better project control'.
Notifiable Projects and the F10
Not all CDM projects require notification to the HSE — but some do, and failing to notify where required is a breach of the regulations. Notification is made using Form F10, submitted online via the HSE website before the construction phase begins.
A project is notifiable if it meets either of two thresholds:
- Duration + workforce: More than 30 working days AND more than 20 workers simultaneously on site at any point in the project
- Person-days: More than 500 person-days total (e.g. 10 workers × 50 days)
Table 02 / HSE notification
Is Your Project Notifiable? F10 Thresholds at a Glance
| Threshold | Trigger | F10 Required? |
|---|---|---|
| Duration + workforce | More than 30 working days AND more than 20 workers simultaneously on site at any point. | Yes — notify before construction starts. |
| Person-days | More than 500 person-days in total, for example 10 workers × 50 days. | Yes — notify before construction starts. |
| Small project | Under 30 working days OR fewer than 20 workers simultaneously. | No — but CDM duties still apply. |
| Domestic client, one contractor | Single contractor working on a homeowner's property. | Unlikely — thresholds are rarely met; the contractor takes on client duties. |
Source: CDM Regulations 2015, Regulation 6. Notification is the client's responsibility but is often submitted by the Principal Contractor or Principal Designer on the client's behalf.
The F10 notification is the client's responsibility to ensure is submitted, though in practice the Principal Contractor or Principal Designer often submits it on the client's behalf. The F10 records key project details: client, Principal Designer, Principal Contractor, site address, expected start date, duration, and estimated workforce.
Safety Clarity notes that even when a project is not notifiable, CDM duties still apply in full. The F10 threshold determines whether you must notify the HSE — not whether CDM applies to you.
If project circumstances change and the project becomes notifiable after work has started — for example, if the programme extends or workforce grows — you must notify the HSE as soon as you become aware. An updated F10 must be submitted whenever key details change significantly.
The Three Key CDM Documents
CDM 2015 requires three core documents to be produced and maintained during a project. Understanding what each contains — and who produces it — is essential for every construction professional.
1. Pre-Construction Information (PCI)
The Pre-Construction Information is compiled by the client and Principal Designer before the construction phase begins. It contains everything relevant to health and safety that is known about the site, the existing structure, and the design: ground conditions, contamination data, existing services, asbestos surveys, structural information, and any other known hazards.
The PCI must be provided to every contractor and designer who needs it. It is not a document that gets filed away — it is working information that informs the Construction Phase Plan and helps contractors plan their work safely.
2. Construction Phase Plan (CPP)
The Construction Phase Plan is prepared by the Principal Contractor before the construction phase starts. It describes how health and safety will be managed throughout the project: site rules, access arrangements, emergency procedures, welfare facilities, high-risk activities, and how the Principal Contractor will coordinate health and safety across all contractors.
The CPP is a living document — it must be updated as the project progresses. It is not a template to be filled in once and forgotten. HSE guidance requires the plan to be project-specific and proportionate to the risks involved. A generic CPP that has not been adapted to the project fails the duty.
On projects with only one contractor (no PC required), the contractor must still produce a Construction Phase Plan. It is required on all projects, notifiable or not.
3. Health and Safety File (H&S File)
The Health and Safety File is compiled by the Principal Designer and handed to the client at the end of the project. It records information needed for future construction work on the building — maintenance, repair, cleaning, refurbishment or demolition.
The H&S File should contain: as-built drawings, structural information, materials used, location of services, details of any hazardous materials left in the structure, and any other information relevant to future safe working. The client must keep the file and make it available to anyone who needs it for future work on the building.
CDM 2015 and the QS: Why It Matters Commercially
CDM 2015 is often seen as a health and safety concern rather than a commercial one — but that misses the practical reality. For quantity surveyors and commercial managers, CDM has direct commercial implications:
- Procurement and appointments: Principal Designer and Principal Contractor appointments must be in writing and made before work starts. Failing to formalise these appointments is a client-side breach. QSs managing procurement must ensure these appointments are correctly placed.
- Programme: CDM compliance takes time. Pre-construction information must be gathered, the CPP must be produced and reviewed, and welfare facilities must be in place before anyone starts work. These steps need programme allowance.
- Cost: Welfare facilities, induction processes, site H&S management, and CDM coordination are real project costs. They must be reflected in preliminary costs and tender documentation.
- Liability: If a QS prepares specifications or designs elements of a scheme, they may carry designer duties under CDM 2015. Understanding when you become a 'designer' for CDM purposes is important for professional liability.
- Final account: CDM documentation can affect final account negotiations — particularly where inadequate pre-construction information contributed to unforeseen ground conditions or hazardous material discoveries.
Common CDM Failures and How to Avoid Them
HSE enforcement data consistently shows the same failures appearing across construction sites. Understanding these helps you avoid them:
Appointments not made in writing. Principal Designer and Principal Contractor appointments must be formal and documented. Verbal agreements or assumed roles do not satisfy the duty.
Generic Construction Phase Plans. The HSE is clear that a CPP must be project-specific. A template downloaded from the internet and filled in with the project name is not adequate. The plan must address the specific risks of this site and this project.
Pre-construction information not shared. Gathering PCI but failing to provide it to contractors and designers who need it defeats the purpose. Information must be actively communicated, not just filed.
Domestic client duties overlooked. Many smaller contractors do not realise that when working for a domestic client, the client's CDM duties transfer to them. This includes producing a Construction Phase Plan even for small residential jobs.
Late F10 notification. Notification must happen before the construction phase starts, not once work is underway. Build notification into project start-up procedures.
Frequently Asked Questions
Does CDM 2015 apply to small projects?
Yes. CDM 2015 applies to all construction work, regardless of size or duration. Some duties — like appointing a Principal Designer and Principal Contractor — only apply when more than one contractor is involved. But duties around planning, managing, monitoring and coordinating health and safety apply to every project, including single-contractor jobs.
Who is responsible for submitting the F10 to the HSE?
Ultimately, the client is responsible for ensuring the F10 is submitted. In practice, it is often the Principal Contractor or Principal Designer who submits it on the client's behalf. The F10 must be submitted via the HSE website before construction work starts. The acknowledgement email should be kept as proof of notification.
What is the difference between a Principal Designer and a CDM Coordinator?
The CDM Coordinator was a role under CDM 2007. CDM 2015 replaced it with the Principal Designer, who has broader and earlier responsibilities. The PD must be a designer with control over the pre-construction phase — not just a coordinator appointed to manage paperwork.
Can one person fulfil multiple CDM roles?
Yes. On smaller projects, the same person or organisation may act as both designer and Principal Designer, or as client and Principal Contractor. However, each role carries its own duties, and whoever holds it must be competent to fulfil them. The client cannot simply self-appoint without having the required skills and capability.
What happens if CDM duties are not met?
Non-compliance is a criminal offence. The HSE can issue improvement notices, prohibition notices, and prosecution. Individuals and organisations can face unlimited fines and — in serious cases — custodial sentences. Directors and senior managers can be personally prosecuted where failures are attributable to their decisions.
Does CDM 2015 apply to maintenance work?
Yes, if the work falls within the definition of 'construction work' under CDM 2015. Maintenance, repair, cleaning, redecoration and refurbishment all fall within scope. The scale of CDM compliance should be proportionate to the risks and complexity of the work.
How does CDM 2015 interact with the Building Safety Act?
The Building Safety Act 2026 extends accountability requirements significantly, particularly for higher-risk buildings. Under the Building Safety Act, principal contractors face broader accountability beyond traditional site H&S — including lifecycle building safety, regulatory reporting and evidence-based compliance. CDM 2015 remains in force alongside the Building Safety Act.
Getting to grips with construction law? Read our guides on NEC4 contracts, JCT contracts, compensation events and commercial management for quantity surveyors.
Sources / Further reading
Official guidance and contractor resources
