CDM 2015 is the Construction (Design and Management) Regulations 2015, the main law for managing health, safety and welfare on construction projects in Great Britain. It is often treated as a big-site rule, but it applies to every construction project, from a new office block to a loft conversion, a kitchen extension or a single tradesperson repairing a roof for a homeowner. What changes with the size of a job is not whether CDM applies but whether the project has to be notified to HSE, and how much planning and paperwork is proportionate to the risks.
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What is CDM 2015?
The Construction (Design and Management) Regulations 2015 (SI 2015/51) came into force on 6 April 2015 and replaced CDM 2007. They are made under the Health and Safety at Work etc. Act 1974 and sit on top of the general duties in that Act and the Management of Health and Safety at Work Regulations 1999, rather than replacing them.
The idea behind CDM is that much of the risk on a construction project is created, or could be removed, before anyone picks up a tool. Decisions about design, sequencing, time and budget shape how dangerous the work will be, so CDM gives legal duties to the people who make those decisions, not just to the builders on site. HSE’s overview says CDM aims to help everyone plan the work sensibly, have the right people for the right job at the right time, cooperate and coordinate, share information about risks, and consult workers.
The Regulations have five parts: definitions and scope (Part 1), client duties (Part 2), the duties of designers and contractors (Part 3), general requirements for all construction sites (Part 4) and transitional provisions (Part 5). HSE’s main guidance is L153, Managing health and safety in construction, which is free to download. L153 is guidance on the Regulations; the Approved Code of Practice that supported CDM 2007 was withdrawn in 2015. A government post-implementation review published in September 2020 recommended keeping CDM 2015.
Does CDM 2015 apply to small jobs and domestic work?
Yes. This is the most common misunderstanding about CDM. Asked whether CDM affects a general builder who only does small commercial and domestic jobs, HSE’s FAQ answers: “Yes. CDM 2015 applies to all construction work including domestic projects.” L153 makes the same point about notification: the requirements of CDM 2015 apply whether or not a project is notifiable.
The size and shape of a project change three things:
- Whether you must notify HSE. Only projects above the thresholds in regulation 6 are notifiable.
- Whether a principal designer and principal contractor are needed. That depends on the number of contractors, not on size or cost.
- How much paperwork is proportionate. HSE says a construction phase plan should be proportionate to the size and scale of the job.
There is one genuine exclusion. HSE’s summary of duties says that if householders carry out work on their own home themselves, it is classed as DIY and CDM 2015 does not apply. CDM applies when someone else does the work for them in the course of a business.
Does CDM apply to my job? A quick checklist
- Is it construction work? Building, altering, renovating, repairing, redecorating, maintaining, demolishing, excavating, or installing or removing fixed services such as electrics, gas and plumbing all count. If yes, CDM applies.
- Is a householder doing the work on their own home themselves? If yes, it is DIY and CDM does not apply. If someone is doing it for them as a business, the householder is a domestic client.
- Is the client a business? Landlords, developers, housing associations and charities are commercial clients, even when the property is a home.
- Will there be more than one contractor at any point? If yes, the client must appoint a principal designer and principal contractor in writing.
- Will the work last more than 30 working days with more than 20 workers on site at once, or exceed 500 person days? If yes, it must be notified to HSE.
- Is there a construction phase plan? Every project needs one before the site is set up.
- Is welfare in place from day one? Toilets, washing facilities, drinking water and a rest area are required on every site.
What counts as construction work under CDM 2015?
Regulation 2 defines construction work as “the carrying out of any building, civil engineering or engineering construction work”, and the list of what it includes is wide:
- construction, alteration, conversion, fitting out, renovation, repair, upkeep, redecoration, maintenance, demolition or dismantling of a structure, including cleaning with high-pressure water or abrasives, or with corrosive or toxic substances;
- site clearance, exploration, investigation and excavation, but not site survey or pre-construction archaeological investigation;
- assembling or disassembling prefabricated elements on site, and removing a structure or its demolition waste; and
- installing, maintaining, repairing or removing mechanical, electrical, gas, telecommunications, computer or similar services normally fixed within or to a structure.
Mineral exploration and extraction are excluded. “Structure” is also broad: it covers buildings, roads, bridges, pipelines, drainage, walls and masts, and also scaffolds and formwork. Because repair and redecoration are on the list, a painter in an occupied office or an electrician rewiring a flat is doing construction work. HSE’s FAQ adds that not all maintenance work is covered and that the position did not change from CDM 2007, so where the line falls depends on the work itself. If in doubt, check L153.
Who are the duty holders under CDM 2015?
CDM 2015 has seven roles. One organisation can hold more than one role on the same project, provided it has the skills, knowledge, experience and organisational capability for each.
| Duty holder | Who they are | Main duties in plain English | Regulations |
|---|---|---|---|
| Client | Anyone for whom a project is carried out as part of a business | Make suitable arrangements for managing the project, with enough time and resources; provide pre-construction information; appoint a principal designer and principal contractor where needed; make sure there is a construction phase plan and, where relevant, a health and safety file; notify HSE; make sure welfare is provided | 4, 5, 6 |
| Domestic client | Someone having work done on their own or a family member’s home, not for a business | In scope, but client duties pass to the contractor, principal contractor or, by written agreement, the principal designer | 7 |
| Designer | Anyone who prepares or modifies a design as part of a business, including architects, engineers, contractors and clients | Eliminate foreseeable risks so far as reasonably practicable, reduce or control the rest, and pass on information | 9 |
| Principal designer | A designer appointed in writing where there is more than one contractor | Plan, manage, monitor and coordinate the pre-construction phase; help with pre-construction information; prepare the health and safety file; liaise with the principal contractor | 11, 12 |
| Principal contractor | A contractor appointed in writing where there is more than one contractor | Plan, manage, monitor and coordinate the construction phase; draw up the construction phase plan; provide site induction; prevent unauthorised access; provide welfare; consult workers | 12 to 14 |
| Contractor | Anyone who carries out, manages or controls construction work as a business, including sub-contractors and the self-employed | Plan, manage and monitor their own work; use competent workers; provide supervision, information and induction; write the construction phase plan if they are the only contractor | 15 |
| Worker | Anyone working for or under the control of a contractor on site | Cooperate with others, follow site rules and report anything likely to endanger health or safety | 8 |
Clients carry more than many expect. Under regulation 4, they must give pre-construction information, such as an existing health and safety file or an asbestos survey, to every designer and contractor appointed or being considered, and take reasonable steps to make sure the principal designer and principal contractor do their jobs. Under regulation 5, a commercial client that fails to appoint a principal designer or principal contractor when one is needed must carry out those duties itself.
A designer must take account of the general principles of prevention and any pre-construction information when designing, so that risks to the people who will build, maintain, clean or use the structure are designed out where reasonably practicable. Our guide to CPD requirements for architects covers how designer duties fit with professional competence schemes. HSE’s FAQ is clear that a principal designer must actually be a designer with control over the pre-construction phase, and that a client can take on the role if competent to do so.
What are a domestic client’s duties under CDM 2015?
A domestic client is someone having construction work done on their own home, or the home of a family member, that is not connected with a business. L153 says local authorities, housing associations, charities, landlords and other businesses that own homes are not domestic clients, and nor is someone having work done on a shop attached to their house.
Domestic clients are within CDM, but regulation 7 moves their client duties to someone else:
- One contractor: the contractor takes on the client duties as well as their own. HSE says this should involve little more than a contractor normally does to manage health and safety risks.
- More than one contractor: the principal contractor takes on the client duties. If the homeowner has not made the appointments, the contractor in control of the construction phase is the principal contractor and the designer in control of the pre-construction phase is the principal designer.
- Written agreement: a homeowner who has engaged an architect or other designer can agree in writing that the principal designer will carry out the client duties instead.
So for a contractor quoting for domestic work, the job includes planning and resourcing, welfare, the construction phase plan and, if the project crosses the threshold, notification.
When does a construction project need to be notified to HSE?
Under regulation 6, a project is notifiable if the construction work on a construction site is scheduled to:
- last longer than 30 working days and have more than 20 workers working simultaneously at any point; or
- exceed 500 person days.
Both tests are “more than”. A “working day” is any day on which construction work takes place, and HSE’s FAQ confirms that weekends and bank holidays count if work happens on them. Person days are found by adding up the days each person works on site. Ten people working for 51 days is 510 person days, so that project is notifiable even though it never has more than 20 workers on site.
The client must notify in writing as soon as practicable before the construction phase begins. For a domestic client, the contractor or principal contractor notifies, or the principal designer if there is a written agreement. HSE’s F10 page says it no longer processes paper forms or accepts notifications by email or post, so notification is made online. The notice must be displayed in the site office and updated if necessary. If a project grows so that it meets the criteria, L153 says it must be notified as soon as possible. Work enforced by the Office of Rail and Road, or on nuclear and certain defence sites, is notified to the ORR or the Office for Nuclear Regulation instead.
Notification does not switch on any other duty. A non-notifiable job still needs a construction phase plan, welfare facilities, competent people and, with more than one contractor, a principal designer and principal contractor.
Does every project need a construction phase plan?
Yes. The construction phase plan is the one CDM document that applies to the smallest job. Under regulation 4(5)(a), the client must make sure a plan is drawn up before the construction phase begins, by the contractor if there is only one or by the principal contractor. Regulations 12(1) and 15(5) put the matching duties on the principal contractor and the sole contractor.
The plan must set out the health and safety arrangements and site rules. Where relevant, it must include specific measures for the high-risk work in Schedule 3, such as work with a particular risk of falling from height, work near high voltage power lines, work with explosives or the assembly of heavy prefabricated components. For a small job, HSE says “a simple plan before the work starts is usually enough”. HSE’s short leaflet for builders, CIS80, states that a plan is required for every construction project and includes a blank template, and HSE points small builders to CITB’s free CDM Wizard app. A plan is not a method statement: the plan covers the whole site, while a method statement sets out how one task will be done. Our guide on what a method statement is explains the difference.
When is a health and safety file needed?
The health and safety file is narrower. The principal designer prepares it under regulation 12(5), so in practice it is required where there is more than one contractor. It holds information needed for the safety of anyone doing future work on the structure, such as maintenance, alteration or demolition. At the end of the project it passes to the client, who must keep it available and hand it on if they sell their interest in the building. A single-contractor job needs a plan but not a file.
What competence and training does CDM 2015 require?
CDM 2015 does not list approved courses or cards. Regulation 8 requires designers and contractors, including principal designers and principal contractors, to have the skills, knowledge, experience and, if an organisation, the organisational capability to do the role safely, and not to accept an appointment unless they do. Whoever appoints them must take reasonable steps to check. L153 says those checks should be proportionate and warns that excessive paperwork can distract from managing risk.
On site, regulation 15 requires contractors to use only workers who have, or are obtaining, the necessary skills, knowledge, training and experience, and to give them supervision, information and a suitable site induction. We cover those duties, and where CSCS cards fit, in construction worker training requirements. Specific hazards bring their own training duties too, as explained in who needs working at height training.
What happened to the CDM co-ordinator?
Under CDM 2007, clients of notifiable projects had to appoint a CDM co-ordinator. CDM 2015 removed that role and created the principal designer. Where a project that began before 6 April 2015 had a co-ordinator, Schedule 4 required the client to appoint a principal designer before 6 October 2015, unless the project had finished.
The roles are not interchangeable. L153 says principal designers are not a direct replacement for CDM co-ordinators because their duties are different, and the principal designer must be a designer in control of the pre-construction phase. The trigger changed too. Under CDM 2007 the extra appointments depended on whether a project was notifiable; under CDM 2015 they depend on whether there is more than one contractor.
What are the general site and welfare requirements under CDM 2015?
Part 4 (regulations 16 to 35) sets minimum standards for every construction site. Contractors must comply so far as the requirements affect their workers or matters in their control, and so must a domestic client who controls the way work is carried out. The topics include safe places of work and access; good order and site security, including marking or fencing off the site perimeter where necessary; stability of structures, demolition and explosives; excavations, cofferdams and caissons; overhead power cables and underground services; prevention of drowning; traffic routes and vehicles; fire, emergency procedures and emergency routes; and fresh air, temperature, weather protection and lighting. Work at height is not covered in Part 4: it is governed by the Work at Height Regulations 2005, which apply alongside CDM.
Welfare is set out in Schedule 2 and applies from the first day on every site, including small domestic jobs. The minimum is suitable toilets; washing facilities with hot and cold or warm running water, soap and drying; drinking water; changing rooms and lockers where needed; and rest facilities with tables, seats with backs, a means of boiling water and somewhere to eat. On a domestic job the contractor may agree with the homeowner to use facilities in the house, but making sure welfare is provided remains the contractor’s legal duty.
Does CDM 2015 apply in Scotland, Wales and Northern Ireland?
CDM 2015 applies across Great Britain, meaning England, Scotland and Wales. Northern Ireland has its own Construction (Design and Management) Regulations (Northern Ireland) 2016, in operation since 1 August 2016, which follow the same model and notification thresholds, with notices going to the Health and Safety Executive for Northern Ireland.
In England there is also a second set of roles with the same names. Since 1 October 2023, Part 2A of the Building Regulations 2010 has required clients to appoint a principal designer and principal contractor for Building Regulations compliance where there is more than one contractor. These are separate legal roles from the CDM ones, although the same firm can hold both, and regulation 11D(2) lets a client certify in writing that its CDM appointees also hold the Building Regulations roles.
Breaching CDM 2015 is a criminal offence under section 33 of the Health and Safety at Work etc. Act 1974.
What CDM and construction health and safety training is available online?
Nexis CPD’s Health and Safety in Construction course covers why construction carries such high risk, the key legal duties including the CDM Regulations, the main safety and health hazards on site, and the controls that keep people safe. Method Statement Awareness covers how safe systems of work are written and followed, and Working at Height Awareness covers one of the most serious construction hazards.
£9 per course. CPD accredited, 100% online, verifiable e-certificate. Pay for 2, get 3 — any 3 courses for £18. These are CPD-accredited awareness courses. They are not a CSCS card, an SMSTS or SSSTS qualification or a NEBOSH construction qualification, and they are not a route to demonstrating principal designer or principal contractor competence. They do not replace site induction, task-specific training or supervision.
Frequently asked questions
Does CDM 2015 apply to domestic projects?
Yes. CDM 2015 applies to all construction work, including work on people’s homes. The homeowner is a domestic client, and their client duties pass to the contractor, the principal contractor or, by written agreement, the principal designer. CDM does not apply where householders do the work on their own home themselves.
When does a construction project need to be notified to HSE?
When the construction work is scheduled to last longer than 30 working days and have more than 20 workers on site at the same time at any point, or to exceed 500 person days. Notification is made online using form F10 before the construction phase begins.
Do I need a construction phase plan for a small job?
Yes. Every project needs a construction phase plan before the construction phase begins, drawn up by the only contractor or the principal contractor. It should be proportionate, and HSE says a simple plan is usually enough for a small job.
When do you need a principal designer and principal contractor?
Whenever there is, or will foreseeably be, more than one contractor on the project. The client must appoint both in writing before the construction phase begins. A commercial client that fails to appoint them must carry out their duties itself.
Is the CDM co-ordinator still a role?
No. CDM 2015 replaced the CDM co-ordinator with the principal designer, with transitional arrangements that ended in October 2015. HSE says the principal designer is not a direct replacement, because the role must be held by a designer in control of the pre-construction phase.
Does CDM 2015 apply in Northern Ireland?
No. CDM 2015 covers England, Scotland and Wales. Northern Ireland has its own Construction (Design and Management) Regulations (Northern Ireland) 2016, with the same notification thresholds.
This article is general information about the Construction (Design and Management) Regulations 2015, not legal advice. It reflects the Regulations and HSE guidance as we found them on 10 October 2026. For a specific project, read the Regulations and HSE’s L153 guidance, and take advice from a competent health and safety adviser where you need it. Nexis CPD courses are CPD-accredited awareness training, not regulated qualifications, CSCS cards, SMSTS, SSSTS or NEBOSH qualifications.