CDM 2015 — the Construction (Design and Management) Regulations 2015 — is the primary health and safety legislation governing construction work in the UK. It applies to virtually every construction project, from a domestic extension to a major infrastructure scheme, and it places legal duties on everyone involved — clients, designers, and contractors.
For UK contractors, understanding CDM 2015 is not optional. It determines your legal responsibilities on every project you work on, defines the documents you need to produce, and sets out what you must do before work begins. Getting it wrong does not just risk an HSE enforcement notice — it can mean personal liability for a director or sole trader if a worker is seriously injured on a project where CDM duties were not met.
This guide explains CDM 2015 in plain English — who the duty holders are, what each one must do, when CDM applies, what documents are required, and the most common mistakes contractors make.
What is CDM 2015?
The Construction (Design and Management) Regulations 2015 replaced the previous CDM 2007 regulations and came into force on 6 April 2015. They were developed to improve health and safety outcomes in the construction industry by integrating health and safety planning into every stage of a project — from initial design through to completion and handover.
The core principle of CDM 2015 is that health and safety should be considered from the very beginning of a project — not added on at the end. By requiring clients, designers, and contractors to think about how a building will be constructed, maintained, and eventually demolished from the design stage, CDM 2015 aims to eliminate hazards before they reach site rather than managing them once they arrive.
The HSE is the enforcing authority for CDM 2015 on construction sites. HSE inspectors can visit any construction site unannounced and require evidence that CDM duties are being met. Failure to comply can result in improvement notices, prohibition notices, and prosecution.
Does CDM 2015 apply to my project?
CDM 2015 applies to all construction work in Great Britain. There is no minimum threshold for CDM to apply — it covers every construction project regardless of size, duration, or value.
However, the specific duties and the documents required vary depending on the scale and nature of the project. The key thresholds that determine what is required are:
All construction projects — CDM 2015 applies. Every contractor has duties regardless of project size.
Projects lasting more than 30 working days with more than 20 workers simultaneously, or exceeding 500 person-days — these are notifiable projects. The client must notify the HSE before work begins by submitting an F10 notification. A principal designer and principal contractor must be formally appointed.
Projects involving more than one contractor — a principal contractor must be appointed to coordinate health and safety during the construction phase.
The definition of "construction work" under CDM 2015 is broad. It includes building, alteration, conversion, fitting out, commissioning, renovation, repair, maintenance, and demolition. It covers not just commercial construction but also domestic work — homeowners having building work done are CDM clients, though their duties are more limited than commercial clients.
The CDM 2015 duty holders
CDM 2015 allocates health and safety responsibilities to named duty holders — specific roles with defined legal obligations. Understanding which role applies to you on any given project is the starting point for CDM compliance.
The client
The client is the organisation or individual for whom the construction work is being carried out. On a commercial project this is typically a company, a public body, or a developer. On a domestic project it is the homeowner.
Commercial client duties include:
- Ensuring suitable arrangements are in place for managing the project, including welfare facilities
- Appointing a principal designer in writing where more than one contractor is involved
- Appointing a principal contractor in writing where more than one contractor is involved
- Ensuring the principal designer and principal contractor carry out their duties
- Providing pre-construction information to designers and contractors
- Ensuring the construction phase does not start until a construction phase plan is in place
- Ensuring the health and safety file is prepared, reviewed, updated, and handed over at project completion
Domestic clients — where the client is having work done on their own home — have most of their duties transferred to the contractor or principal contractor by default. However, domestic clients can formally appoint a principal designer if they choose.
The principal designer
The principal designer is appointed by the client on projects involving more than one contractor. They are responsible for planning, managing, and coordinating health and safety during the pre-construction phase.
In practice, the principal designer is typically an architect, structural engineer, or specialist H&S consultant with design responsibility on the project. Their key duties include:
- Identifying, eliminating, and controlling foreseeable risks during the design stage
- Ensuring designers cooperate and communicate with each other on H&S matters
- Preparing and maintaining the pre-construction information pack
- Liaising with the principal contractor throughout the project
- Preparing the health and safety file for handover at completion
The principal contractor
The principal contractor is appointed by the client on projects involving more than one contractor. They are responsible for planning, managing, monitoring, and coordinating health and safety during the construction phase.
For most UK building contractors, the principal contractor role is the one most directly relevant to day-to-day site operations. Principal contractor duties include:
- Developing and maintaining the construction phase plan before work starts
- Managing and monitoring the health and safety of all contractors on site
- Ensuring suitable site inductions are provided to all workers
- Ensuring all contractors have appropriate risk assessments, method statements, and permits in place
- Consulting with workers on health and safety matters
- Displaying the F10 notification on site (where applicable)
- Coordinating welfare facilities for all workers on site
- Liaising with the principal designer throughout the project
- Contributing to and handing over the health and safety file at completion
Contractors
Every business or individual carrying out construction work on a project — other than the principal contractor — is a contractor under CDM 2015. This includes subcontractors, self-employed tradespeople, and specialists brought in for specific elements of the work.
Contractor duties under CDM 2015 include:
- Planning, managing, and monitoring their own work to ensure it is carried out safely
- Cooperating with the principal contractor and other contractors on site
- Providing the principal contractor with relevant health and safety information — including risk assessments, method statements, and details of any risks their work creates for others
- Complying with instructions given by the principal contractor
- Ensuring all workers they employ or engage are appropriately trained, competent, and inducted onto the site
- Not starting work on site until a construction phase plan is in place
- Reporting anything they observe that is likely to endanger the health or safety of themselves or others
As a contractor, you do not need to be involved in the appointment of the principal designer or the preparation of the health and safety file — but you must cooperate with those who are, and you must fulfil your own duties in relation to your specific scope of work.
Designers
Anyone who prepares or modifies a design for construction work — including architects, structural engineers, mechanical and electrical engineers, and specialist subcontractors who design their own installations — has duties as a designer under CDM 2015. Designers must eliminate foreseeable risks through their design decisions wherever possible and provide information about residual risks to those carrying out the work.
Workers
Workers on a construction site have their own duties under CDM 2015 — to cooperate with their employer and others, to report anything likely to endanger health and safety, and to use equipment and materials in accordance with their training and instructions.
The key CDM 2015 documents
CDM 2015 requires or implies the production of several key documents. As a contractor, you will encounter most of these on every project.
Pre-construction information
Pre-construction information is prepared by the client and principal designer and provided to all contractors before they price and plan their work. It contains information about the site and the project that could affect how work is planned and carried out safely — existing services, ground conditions, asbestos surveys, structural surveys, and any known hazards.
As a contractor, you should always ask for pre-construction information before pricing a job and before planning your scope of work. If it has not been provided, ask for it — the client has a legal duty to provide it.
Construction phase plan
The construction phase plan is prepared by the principal contractor before the construction phase begins and maintained throughout the project. It sets out how the project will be managed safely — the arrangements for managing health and safety, the site rules, the welfare arrangements, and the process for managing contractor coordination.
As a contractor on a project, you should be provided with the relevant sections of the construction phase plan during your site induction. You must comply with it.
If you are the only contractor on a project — making you the principal contractor by default — you are responsible for preparing the construction phase plan. For small domestic projects this does not need to be a complex document, but it must exist before work starts.
Health and safety file
The health and safety file is prepared by the principal designer during the project and handed to the client at completion. It contains information about the completed building that will be needed for future maintenance, alteration, and demolition — as-built drawings, details of buried services, materials used, and residual risks in the structure.
As a contractor, you may be required to contribute information to the health and safety file — particularly if your work involves installing services, creating structural elements, or introducing materials that future contractors will need to know about.
Risk assessments and method statements
Every contractor must have suitable and sufficient risk assessments in place for their scope of work before starting on site. For work involving significant hazards — working at height, hot work, confined space entry, work on live electrical systems — a method statement describing how the work will be carried out safely is expected alongside the risk assessment.
The principal contractor will request your RAMS as part of the pre-start documentation review. Having task-specific, site-specific RAMS ready before you arrive on site is a basic expectation of every principal contractor in the UK.
→ Browse all risk assessment templates
→ Browse all RAMS and permit templates
F10 notification
On notifiable projects — those exceeding 30 working days with more than 20 simultaneous workers, or 500 person-days — the client must notify the HSE before construction begins by submitting an F10 notification online at the HSE website. The notification is then displayed on site throughout the project.
As a contractor, you are not responsible for submitting the F10 — that is the client's duty. But you should be aware of whether the project you are working on is notifiable, and you should expect to see the F10 displayed in the site office or welfare facilities on any notifiable project.
CDM 2015 and subcontractor management
One of the most practically important aspects of CDM 2015 for principal contractors is the management of subcontractors. Every subcontractor you bring onto a project becomes a CDM contractor — and you, as principal contractor, are responsible for ensuring they meet their duties.
In practice this means:
Pre-qualification — before appointing a subcontractor, satisfy yourself that they are competent to carry out the work safely. Check their relevant qualifications, training records, and previous experience.
RAMS review — request and review risk assessments and method statements for every subcontractor's scope of work before they start. A subcontractor RAMS review form documents your assessment of each submission.
→ Download the Sub-Contractor RAMS Review Template — £3.99
Induction — ensure every subcontractor operative receives a site-specific induction before starting work. The induction must cover site rules, emergency procedures, welfare arrangements, and the specific hazards relevant to the current phase of the project.
Ongoing monitoring — your duty as principal contractor does not end at induction. You must monitor subcontractor compliance with the construction phase plan and their own RAMS throughout the project.
RAMS action tracking — on projects with multiple subcontractors, a RAMS action tracker helps manage the status of RAMS submissions, reviews, and acceptances across all trades.
→ Download the RAMS Action Tracker — £3.99
The most common CDM 2015 mistakes contractors make
Starting work before the construction phase plan exists. This is one of the most frequently cited CDM failures. On notifiable projects and multi-contractor projects, the construction phase plan must be in place before work starts. No plan, no start.
Generic risk assessments not specific to the project. CDM 2015 requires suitable and sufficient risk assessments — which means task-specific and site-specific. A generic risk assessment that could apply to any job on any site does not meet the standard. The HSE expects to see assessments that reflect the actual hazards on the actual site.
Failing to provide pre-construction information. Clients who do not gather and share relevant information about the site — existing services, asbestos surveys, structural surveys — are failing their CDM duty and creating risks for contractors who price and plan work without that information.
Not appointing a principal designer in writing. Where a project involves more than one contractor, a principal designer must be appointed in writing before the design phase begins. Verbal arrangements or assumptions about who is fulfilling this role are not sufficient.
Inadequate subcontractor management. Principal contractors who allow subcontractors onto site without reviewing their RAMS, without providing a site induction, and without monitoring their compliance are failing their CDM duties — and are potentially liable if a subcontractor operative is injured.
Welfare facilities that do not meet CDM requirements. CDM 2015 Schedule 2 sets out the minimum welfare facilities required on construction sites — toilets, washing facilities, drinking water, rest facilities, and changing facilities where operatives need to change into PPE. These are legal requirements, not suggestions.
Failing to contribute to the health and safety file. Contractors who complete their work and leave site without providing the information they hold — as-built drawings, materials used, details of installed services — to the principal designer for inclusion in the health and safety file are failing their CDM duty.
CDM 2015 for small contractors and sole traders
CDM 2015 applies to sole traders and small contractors in the same way it applies to large firms. The scale of what is required is proportionate to the scale of the project — a sole trader carrying out a domestic rewire does not need the same documentation as a principal contractor managing a 50-person building site. But the duties exist and must be met.
For sole traders and small contractors, the practical CDM requirements for most jobs are:
- Task-specific risk assessments before work starts
- A method statement for high-risk activities
- Cooperation with any principal contractor on the project
- Compliance with the construction phase plan
- Provision of relevant information to the principal designer for the health and safety file
Having a professional set of H&S documents — risk assessments, RAMS, and permits — ready to present to a principal contractor is the clearest evidence of CDM compliance a small contractor can demonstrate.
Frequently asked questions
Does CDM 2015 apply to domestic projects?
Yes. CDM 2015 applies to all construction work, including domestic projects. However, domestic clients have most of their duties transferred to the contractor or principal contractor by default. The contractor still has their own CDM duties — including risk assessments, method statements, and safe working practices — regardless of whether the client is commercial or domestic.
Who is responsible for appointing a principal contractor?
The client appoints the principal contractor in writing. On commercial projects this is the developer, company, or public body commissioning the work. On domestic projects where the client's duties have transferred, the contractor acts as principal contractor and fulfils those duties.
What happens if no principal contractor is appointed on a multi-contractor project?
All contractors share the principal contractor duties between them, which in practice means no single party is coordinating H&S across the project. This is a common failure on smaller projects and one of the situations where CDM compliance breaks down. The HSE takes failure to appoint seriously.
Is CDM 2015 compliance checked by the HSE?
Yes. HSE inspectors visit construction sites regularly — both planned inspections and unannounced visits. They check for CDM compliance as a standard part of every site visit. The documents they commonly ask to see include the construction phase plan, F10 notification, risk assessments, site induction records, and welfare arrangements.
Where can I find more information about CDM 2015?
The HSE publishes comprehensive guidance on CDM 2015 at hse.gov.uk/construction/cdm. The L153 guidance document — "Managing health and safety in construction" — is the definitive reference for CDM 2015 compliance.
> Related guides: CDM projects frequently involve hazardous substances — a COSHH assessment is required under COSHH Regulations 2002. Working at height is one of the most common CDM risks — see our complete guide to the working at height risk assessment.
Summary
CDM 2015 applies to every construction project in the UK — from a domestic extension to a major commercial build. It allocates health and safety responsibilities to named duty holders — clients, principal designers, principal contractors, contractors, and workers — and requires key documents to be in place before and throughout the construction phase.
For contractors, the practical implications are clear: have task-specific risk assessments and method statements ready before you arrive on site, cooperate fully with the principal contractor, comply with the construction phase plan, and ensure your operatives are properly inducted and supervised.
SafetyPod has the professionally drafted, HSE-compliant H&S document templates you need to demonstrate CDM 2015 compliance on every project — from risk assessments and RAMS to permits to work and monitoring forms.
→ Browse all risk assessment templates
→ Browse all RAMS and permit templates
Written by the SafetyPod team — NEBOSH-qualified H&S professionals with hands-on experience across UK construction, civil engineering, and facilities management. All content is written to current HSE guidance and CDM 2015 compliance.
Last reviewed: May 2026