The Construction (Design and Management) Regulations 2015 (CDM 2015) set out the health and safety duties that apply to construction projects across Great Britain. They help clients, designers and contractors plan work safely, manage risks and protect everyone involved.
CDM 2015 applies to almost all construction projects, regardless of size, cost or duration. A small kitchen renovation, a commercial office refurbishment and a major building project can all fall within the regulations. However, not every project needs to be notified to the Health and Safety Executive (HSE).
If you are a client, small builder or subcontractor, understanding when the CDM regulations apply is an important part of your legal responsibilities. This guide explains what counts as construction work, when a project becomes notifiable and what you need to know about domestic and commercial projects.
When Does CDM 2015 Apply?
CDM regulations 2015 apply when construction work falls within the scope of the regulations. They cover the planning, design, management and execution of construction work, with duties shared between the people involved in a project.
The regulations are not limited to large building sites. They can apply to small jobs carried out by a single tradesperson, as well as projects involving several contractors and specialist designers.
For example, CDM 2015 may apply to:
- Building a new house or commercial property.
- Extending a home or business premises.
- Renovating a kitchen or bathroom.
- Refurbishing offices, shops or other workplaces.
- Structural repairs and alterations.
- Demolition and dismantling work.
- Certain maintenance and repair projects.
The exact duties depend on the project, the roles involved and whether the client is acting privately or as part of a business.
Who Has Responsibilities Under CDM 2015?
The regulations assign duties to several groups. Understanding your role helps you identify what you need to do to support CDM compliance.
| Dutyholder | Main responsibility |
| Client | Makes suitable arrangements for managing the project and ensuring health and safety are considered. |
| Designer | Removes, reduces or controls foreseeable health and safety risks through design decisions. |
| Principal designer | Plans, manages and coordinates health and safety during the pre-construction phase when more than one contractor is involved. |
| Principal contractor | Plans, manages and coordinates health and safety during the construction phase when more than one contractor is involved. |
| Contractor | Plans and manages the work under their control and protects workers and others who may be affected. |
| Worker | Follows safe working practices, takes care of their own safety and cooperates with others. |
One organisation or person may hold more than one role, provided they have the necessary skills, knowledge, experience and organisational capability.
For small contractors, this means CDM duties should not be treated as paperwork that only large construction companies need to worry about. You must understand the risks associated with your work and manage them appropriately.
What Counts As Construction Work Under CDM?
The definition of construction work under CDM regulations 2015 is broad. It covers much more than building a new property. It includes many types of alteration, repair, renovation and maintenance work.
Examples include:
- Building and extensions: Constructing a new property, adding an extension or making structural changes.
- Renovation and refurbishment: Updating homes, offices, shops and other buildings.
- Repairs and maintenance: Repairing roofs, replacing structural elements and carrying out certain maintenance tasks.
- Demolition: Taking down a building or removing parts of a structure.
- Installation work: Installing or repairing fixed electrical, gas, heating, plumbing and other building services.
- Site preparation: Excavation, site clearance and other work to prepare for construction.
Not every task carried out in a building is construction work. For example, routine cleaning that does not meet the specific definition in the regulations may fall outside its scope. The nature of the work matters, so do not assume that a job is exempt simply because it is described as maintenance or a minor repair.
What Does This Mean for Small Contractors?
If you are a sole trader, self-employed tradesperson or small building company, CDM compliance still matters.
You must plan and manage the construction work under your control, consider risks to workers and other people, and cooperate with the other dutyholders involved in the project.
The level of planning should be proportionate to the work. A small bathroom renovation does not need the same management arrangements as a large commercial development, but the relevant legal duties still apply.
When Does a Construction Project Become Notifiable?
One of the most common misunderstandings about CDM regulations is the difference between a project that falls under the regulations and one that must be notified to the HSE.
A project becomes notifiable when it is expected to meet either of these conditions:
Condition 1: Duration and workforce
The construction work is expected to last more than 30 working days and have more than 20 workers working simultaneously at any point during the project.
Condition 2: Total person-days
The project is expected to exceed 500 person-days of construction work in total.
These are alternative tests. A project only needs to meet one of them to be notifiable.
What Is a Person-Day?
A person-day represents one person working on the project for one working day.
For example, if 10 workers each work on a project for 50 days, the total is 500 person-days. If the project is expected to exceed that figure, the notification threshold is met.
The calculation concerns the total construction work, not just the number of people employed by one contractor. The planned work and workforce should be considered across the project.
Who Must Notify the HSE?
The client is responsible for ensuring that a notifiable project is notified to the HSE. The client may ask someone else to submit the notification on their behalf.
Notification is normally made using the HSE’s F10 form. The required information must be submitted before construction work starts, and the notification must be displayed at the site as required.
You can find the current requirements in the HSE’s CDM 2015 guidance.
Remember, a project does not need to be notifiable for CDM 2015 to apply. Small projects still have relevant health and safety duties.
Domestic vs Commercial Projects: A Tale of Two Clients
CDM regulations 2015 distinguish between domestic and commercial clients. The main difference is how the client’s legal duties are managed.
What Is a Domestic Client?
A domestic client is someone who arranges construction work on their own home, or a family member’s home, where the work is not connected to a business.
For example, a homeowner hiring a builder to renovate a bathroom would normally be a domestic client.
CDM 2015 still applies to the work. However, the domestic client’s duties are normally transferred to other dutyholders:
- For a project with one contractor, the contractor normally takes on the client’s duties.
- For a project with more than one contractor, the principal contractor normally takes on those duties.
- In certain circumstances, a principal designer can take on the client’s duties through a written agreement.
These arrangements mean domestic clients do not usually have to manage the formal client duties themselves. However, they should still choose suitable contractors and allow enough time and resources for the work to be carried out safely.
What Is a Commercial Client?
A commercial client is an individual or organisation that commissions construction work as part of a business.
Examples include:
- A property developer building new homes for sale.
- A business refurbishing its office.
- A landlord arranging work as part of a property business.
- A retailer fitting out a new shop.
Commercial clients have their own duties under CDM 2015, regardless of the project’s size. These include making suitable arrangements for managing health and safety, appointing the appropriate dutyholders, providing relevant project information and ensuring that a construction phase plan is prepared before construction work begins.
Where a project involves more than one contractor, the client must appoint a principal designer and a principal contractor in writing.
The key point: Do not assume that domestic work is exempt from CDM or that commercial work only needs to comply when it reaches the notification threshold.
Common CDM Myths You Need to Ignore
Misunderstanding the regulations can lead to poor planning and avoidable risks. Here are four common myths worth correcting.
Myth 1: CDM Only Applies to Large Construction Projects
Fact: CDM 2015 applies to construction work of all sizes, including small domestic projects. The notification threshold determines whether the HSE must be notified, not whether the regulations apply.
Myth 2: Small Contractors Do Not Need to Worry About CDM
Fact: Contractors have duties on small projects too. They must plan, manage and monitor the work under their control, taking account of risks to workers and anyone else who could be affected. The arrangements should suit the size and risks of the job.
Myth 3: A Project Is Exempt If It Does Not Need an F10 Notification
Fact: A project can fall under CDM 2015 without being notifiable. The notification thresholds are separate from the duties that apply to clients, designers and contractors.
Myth 4: Only Architects and Engineers Have Designer Duties
Fact: The term designer covers more than traditional design professionals. Anyone who prepares or modifies a construction design, or arranges for others to do so as part of their work, may have designer duties. This can include contractors, tradespeople and interior designers.
Frequently Asked Questions About CDM Regulations 2015
When Do CDM Regulations Apply?
CDM regulations apply to construction work within the scope of the regulations, regardless of project size, cost or duration. They cover domestic and commercial work, including many building, renovation, repair and demolition projects. The duties depend on your role and the circumstances of the project.
Does Replacing a Kitchen or Bathroom Fall Under CDM?
Yes, a kitchen or bathroom replacement carried out by contractors will generally fall within CDM 2015 because it involves construction work, such as fitting, alteration or installation. The duties should be proportionate to the work and its risks. A homeowner carrying out the work entirely as DIY is treated differently under the regulations.
What Happens If We Don’t Notify the HSE?
If a project meets the notification criteria, the client must ensure that the HSE is notified. Failing to meet this requirement can lead to enforcement action. Notifying the HSE does not replace the other duties under CDM 2015, and a project that is not notifiable must still meet the relevant requirements.
Do CDM Regulations Apply to an Interior Designer?
Yes. An interior designer may be classed as a designer under CDM 2015 if they prepare or modify designs for construction work, or arrange for others to do so. They must consider foreseeable health and safety risks, take steps to eliminate or reduce them, and provide relevant information to the project team.
Conclusion
CDM regulations 2015 apply to a wide range of construction projects, from small domestic renovations to large commercial developments. The important thing is to understand which duties apply to your role and make sure health and safety is considered from the planning stage through to completion.
Remember that CDM applies to construction work regardless of project size, while HSE notification is only required when a project meets the relevant thresholds. Understanding this distinction helps clients and contractors plan work properly and avoid common compliance mistakes.
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Explore the available courses or contact Think Construction Skills to discuss suitable training for you or your team.