The Construction (Design and Management) Regulations 2015 — known as CDM 2015 or CDM regulations — are the main UK regulations governing health and safety in construction projects. They apply to every construction project in Great Britain regardless of size, value or duration. If you carry out construction work, design construction work, manage construction sites or commission construction projects, CDM 2015 applies to you.
The regulations create five specific duty holder roles with defined responsibilities at each project stage. Understanding which role you hold and what it requires is not optional — CDM 2015 is criminal law enforced by the Health and Safety Executive, with unlimited fines in the Crown Court and the power to stop work immediately.
What CDM 2015 requires
CDM 2015 came into force on 6 April 2015, replacing the previous CDM 2007 regulations. The regulations implement EU Directive 92/57/EEC (the Temporary or Mobile Construction Sites Directive) into UK law. Despite Brexit, CDM 2015 remains in force in Great Britain under the Health and Safety at Work etc. Act 1974.
The core purpose of CDM 2015 is to ensure health and safety is planned, managed and coordinated throughout every stage of a construction project — from initial design through to completion and handover. The regulations create specific legal duties for clients, designers, principal designers, principal contractors and contractors.
Under Regulation 4, clients must make suitable arrangements for managing the project, ensure that sufficient time and resources are allocated, and ensure that duty holders are appointed only if competent and adequately resourced. Regulation 8 requires that no person may appoint or engage a contractor, designer, principal designer or principal contractor unless they have taken reasonable steps to satisfy themselves of competence.
Regulation 11 requires the principal designer to plan, manage, monitor and coordinate health and safety in the pre-construction phase. Regulation 12 requires the principal contractor to plan, manage and coordinate the construction phase, prepare the construction phase plan before work begins, and ensure suitable site induction and welfare facilities. Regulation 15 requires every contractor to plan, manage and monitor their own work to ensure it is carried out without risks to health and safety.
The regulations do not apply in Northern Ireland, which has its own equivalent Construction (Design and Management) Regulations (Northern Ireland) 2016.
Who CDM 2015 applies to
CDM 2015 applies to all construction work carried out in Great Britain. There are no exemptions based on project size, value, duration or number of workers. The following parties have CDM 2015 duties:
- Clients — any person or organisation commissioning construction work. This includes commercial clients, local authorities, housing associations, property developers and domestic clients (homeowners). Domestic clients have most of their duties transferred to contractors under Regulation 4(7), but the duties still exist and are enforceable.
- Principal designers — required on projects with more than one contractor. Typically an architect, structural engineer, building surveyor or CDM consultant. Must be appointed in writing by the client before the construction phase begins.
- Principal contractors — required on projects with more than one contractor. The main contractor responsible for coordinating the construction phase. If you engage even one subcontractor, you become the principal contractor.
- Designers — any person who prepares or modifies a design for a construction project. This includes architects, engineers, surveyors, and contractors who design temporary works, scaffolding designs, formwork or method statements.
- Contractors — any person or business that carries out, manages or controls construction work. Includes limited companies, partnerships, sole traders, self-employed individuals and labour-only subcontractors. There is no size threshold — a one-person contractor has the same CDM duties as a national construction firm.
Construction work is defined in Regulation 2(1) and includes building work, civil engineering, demolition, refurbishment, maintenance, decoration, installation of services and site clearance. The definition is deliberately broad.
Key duties at a glance
The specific duties under CDM 2015 depend on your role. Here are the core requirements for each duty holder:
- Clients (Regulation 4) — appoint competent and adequately resourced duty holders; ensure sufficient time and resources are allocated for each stage; provide pre-construction information to designers and contractors; ensure the principal designer prepares a health and safety file; retain and provide the health and safety file to anyone who needs it for future work.
- Principal designers (Regulation 11) — plan, manage, monitor and coordinate health and safety in the pre-construction phase; identify and 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 to help plan the construction phase; prepare the health and safety file.
- Principal contractors (Regulation 12) — plan, manage and coordinate the construction phase; prepare the construction phase plan before work starts; organise cooperation between contractors; ensure suitable site induction; provide welfare facilities; prevent unauthorised access; display the F10 notification on notifiable projects; liaise with the principal designer regarding ongoing design.
- Designers (Regulation 9) — eliminate foreseeable risks during design where possible; reduce risks that cannot be eliminated; provide information about remaining risks; ensure designs include adequate information about health and safety; take account of the Construction (Design and Management) Regulations during the design process.
- Contractors (Regulation 15) — plan, manage and monitor own work; ensure workers have appropriate skills, knowledge and training; provide suitable site induction; prevent access by unauthorised persons; comply with directions from the principal designer or principal contractor; ensure own workers are consulted about health and safety matters; provide information to the principal contractor for the health and safety file.
- Workers (Regulation 16) — take care of own health and safety and that of others affected by their actions; report obvious risks; cooperate with others on site. This applies to employees, labour-only subcontractors and agency workers.
On single-contractor projects, there is no requirement to appoint a principal designer or principal contractor. The single contractor must still carry out equivalent planning, management and coordination duties, and must comply with Regulation 15 contractor duties in full.
Penalties for non-compliance
CDM 2015 is enforced by the Health and Safety Executive (HSE). Breaches are criminal offences prosecuted under the Health and Safety at Work etc. Act 1974. The HSE has extensive enforcement powers including improvement notices (requiring specific actions within a set timescale), prohibition notices (stopping work immediately until hazards are controlled), and prosecution in the magistrates' court or Crown Court.
In the Crown Court, fines are unlimited. A principal contractor prosecuted for failing to prepare a construction phase plan or allowing unsafe work can face a fine of tens or hundreds of thousands of pounds. Individuals can also be prosecuted and imprisoned for up to two years for serious breaches or where death or serious injury results.
The HSE's Fee for Intervention (FFI) scheme means that inspectors can charge £163 per hour (2024 rate) for time spent investigating material breaches of health and safety law. A site visit to investigate a missing construction phase plan, inadequate welfare facilities or lack of coordination between contractors can easily result in several hours of chargeable time — costing £500–£1,500 even if no enforcement action follows.
In 2022/23, 45 construction workers were killed at work in Great Britain — the highest total of any sector, according to HSE fatal injury statistics. Falls from height, being struck by moving vehicles, and being struck by moving or falling objects accounted for the majority of fatalities. CDM 2015 exists because construction work kills people, and the regulations are enforced accordingly.
How CDM 2015 relates to risk assessments
CDM 2015 does not replace the requirement for risk assessments under the Management of Health and Safety at Work Regulations 1999. It sits alongside it. Every employer and self-employed person carrying out construction work must carry out a suitable and sufficient risk assessment under Regulation 3 of MHSWR 1999.
The construction phase plan required under Regulation 12 of CDM 2015 must be based on risk assessments for the specific work activities on the project. A compliant construction phase plan will incorporate or reference the risk assessments for the principal contractor's own work, and the arrangements for ensuring subcontractors provide their own risk assessments and method statements before starting work.
On single-contractor projects where no construction phase plan is required, the contractor still needs a suitable and sufficient risk assessment covering the significant hazards of the work — working at height, manual handling, use of work equipment, COSHH substances, excavation, buried services, noise, vibration and site-specific hazards.
Anyrisks generates compliant, site-specific construction risk assessments in under 2 minutes. Each assessment covers CDM 2015 duty holder responsibilities, the significant hazards specific to your trade and site, and the control measures required under UK law. Output is provided as PDF and editable Word document for £29.
CDM 2015 and notifiable projects
A project is notifiable under Regulation 6 if the construction phase will last longer than 30 working days and have more than 20 workers working simultaneously at any point, or if the construction work exceeds 500 person-days. Notifiable projects must be notified to the HSE using the F10 form before the construction phase begins.
Most small domestic extensions, refurbishments, and commercial fit-outs do not meet these thresholds. A 2-person team working for 60 days generates 120 person-days — well below the 500 person-day threshold. A 4-person team would need to work for 125 days to exceed 500 person-days. The 30-day threshold applies only if there are more than 20 workers simultaneously on site, which is rare on small projects.
When a project is notifiable, the principal contractor must display a copy of the F10 notification in a prominent position on site where it can be read by workers and visiting HSE inspectors. Failure to notify a notifiable project is a criminal offence and can result in prosecution and a fine.
The F10 form requires: the address of the construction site; name and address of the client; name and address of the principal designer; name and address of the principal contractor; date planned for the start of the construction phase; the planned duration of the construction phase; estimated maximum number of people at work on the site; and the number of contractors expected to work on the site.
Construction phase plans in practice
The construction phase plan is required under Regulation 12(1) on any project with more than one contractor. It must be prepared before the construction phase begins, and must set out the health and safety arrangements and site rules which will apply during construction. The HSE does not prescribe a specific format — the plan must be proportionate to the size and complexity of the project.
For a small project with 2–3 contractors, a construction phase plan might run to 4–6 pages covering: project details and key contacts; site rules (PPE, access, parking, smoking); welfare arrangements (toilets, washing, drinking water, rest facilities); emergency procedures (first aid, fire, accident reporting); significant risks and control measures (working at height, excavation, manual handling, COSHH); site induction requirements; and coordination arrangements (toolbox talks, method statement approval, permit systems if applicable).
The plan is a live document and must be reviewed and updated as the project progresses under Regulation 12(2). If new hazards arise, additional contractors are engaged, the scope of work changes, or incidents occur, the plan must be updated accordingly.
The principal contractor must ensure that contractors are provided with a copy of the relevant parts of the construction phase plan, and that contractors comply with the rules and arrangements set out in the plan. This is typically done through site induction.
Health and safety file requirements
The health and safety file is required under Regulation 12(5) on projects with more than one contractor, or on notifiable projects. The principal designer must prepare the file during the pre-construction phase and update it throughout the project. At completion, the file is handed to the client.
The file must contain information about the completed structure that will be needed to ensure health and safety during future construction work, maintenance, repair, renovation or demolition. Typical contents include: as-built drawings; information about the structure, materials and equipment (including location of buried services, structural principles, safe load capacities); residual hazards and how they should be managed; and information about removal or dismantling of installed equipment.
The file does not need to include risk assessments, construction phase plans, or information that is readily available elsewhere such as manufacturer instructions. It should be concise, relevant and usable. For a small domestic extension, the file might consist of as-built drawings, a note of the location of buried services, and a brief description of the roof construction and access arrangements for future maintenance.
On domestic projects, the client must be told what the file contains and must keep it available for future use. On commercial projects, the client has a legal duty under Regulation 4(9) to retain the file and provide it to anyone who needs it for the purposes of planning future construction work.
CDM 2015 and small builders
Small builders often assume CDM 2015 is something for large contractors on big sites. This assumption is wrong. A 2-person building firm carrying out loft conversions, extensions and refurbishments is subject to the full requirements of CDM 2015.
If you work alone and engage no subcontractors, you are a contractor under Regulation 15. You must plan, manage and monitor your own work, ensure you are competent for the work you undertake, and carry out risk assessments under MHSWR 1999. You do not need to appoint a principal contractor or prepare a construction phase plan, but all other health and safety law applies.
If you engage even one subcontractor — a plasterer, electrician, plumber or labourer — you become the principal contractor. You must prepare a construction phase plan before work starts, coordinate the work of all contractors, ensure site induction is provided, and manage site health and safety throughout the project. This applies even if the subcontractor works for only one day.
The most common CDM breaches by small builders are: starting multi-contractor work without a construction phase plan; failing to coordinate subcontractors; not checking subcontractor competence; inadequate or missing welfare facilities; no site induction; and failing to control access to the site. These are all straightforward to address, but all are criminal offences if not done.
Need a compliant construction phase plan template? Anyrisks generates site-specific construction risk assessments and can point you to HSE template construction phase plans available free on hse.gov.uk. For complex projects or where you need professional support, consider engaging a CDM consultant or using the toolbox talk resources to ensure workers understand site rules and hazards.
Competence under CDM 2015
Regulation 8 requires that no person may appoint or engage a designer, contractor, principal designer or principal contractor unless they have taken reasonable steps to satisfy themselves that the duty holder is competent and has the skills, knowledge, experience and organisational capability necessary to carry out the work safely.
For small contractors, demonstrating competence typically means: relevant trade qualifications (NVQ, City & Guilds); health and safety training (CSCS card, CITB Site Safety Plus, SMSTS/SSSTS for supervisors); insurance (public liability, employer's liability); membership of a trade body where relevant (FMB, NFRC, Competent Roofer); and a track record of safe working evidenced by method statements, risk assessments and client references.
When engaging a subcontractor, you must check their competence before they start work. This can be done by requesting: proof of relevant qualifications; CSCS card or equivalent; evidence of insurance; examples of risk assessments or method statements; and references from previous clients or principal contractors. The check does not need to be onerous, but it must be documented.
The HSE does not require third-party accreditation schemes, but schemes such as Constructionline, CHAS, SafeContractor and Acclaim can provide evidence of baseline competence. The key requirement is that you can demonstrate you took reasonable steps to check competence before appointment.
Related regulations and guidance
CDM 2015 works alongside several other key sets of regulations. The Work at Height Regulations 2005 apply to all work at height, including ladder work, roof work, scaffolding and MEWPs. The Control of Substances Hazardous to Health Regulations 2002 apply to hazardous substances including cement, silica dust, solvents, paints and adhesives. The Manual Handling Operations Regulations 1992 apply to lifting, carrying and moving materials and equipment. The Provision and Use of Work Equipment Regulations 1998 (PUWER) apply to all tools, plant and machinery.
The HSE publication L153 (Managing Health and Safety in Construction — Construction (Design and Management) Regulations 2015 Guidance on Regulations) is the official Approved Code of Practice for CDM 2015. L153 has special legal status — if you follow its recommendations, you will normally be doing enough to comply with the law. Courts can use non-compliance with L153 as evidence that you have breached CDM 2015. The full text is available to read free on hse.gov.uk.
Additional HSE guidance includes: CIS80 (Permits to work); CIS59 (Confined spaces in construction); HSG151 (Protecting the public — your next move); and industry-specific guidance for groundworks, demolition, scaffolding, working with asbestos, and working near overhead power lines.
