CDM regulations explained
CDM stands for Construction (Design and Management). The CDM Regulations 2015 apply to every construction project in Great Britain, from a bathroom refit to a hospital. They set out who is responsible for planning and managing health and safety, and require a construction phase plan on every project.
The duty holders
| Role | Main duties |
|---|---|
| Client | Make suitable arrangements for managing the project, give pre-construction information, appoint a principal designer and principal contractor when there is more than one contractor, notify HSE (F10) when needed. |
| Domestic client | A homeowner having work done on their own home. Their duties pass to the contractor (one contractor) or the principal contractor (more than one). |
| Principal designer | Plan, manage and coordinate health and safety in the pre-construction phase. |
| Principal contractor | Plan, manage and coordinate the construction phase; prepare the construction phase plan; site induction and welfare. |
| Designer | Eliminate, reduce or control foreseeable risks through the design. |
| Contractor | Plan, manage and monitor their own work; on single-contractor jobs, prepare the construction phase plan. |
| Worker | Work safely, cooperate and report problems. |
What a small contractor must do
- Make sure the client knows their duties (or take them on, for a domestic client).
- Write a construction phase plan before work starts. For small jobs it can be a few pages.
- Give each worker a site induction and the information they need.
- Provide welfare: toilets, washing, drinking water, somewhere to rest and change. On domestic jobs you can agree to use the client's facilities.
- Plan the work so it is done safely, which is where RAMS come in.
When does HSE need to be notified?
When the construction work will last more than 30 working days with more than 20 workers on site at the same time, or will exceed 500 person days. See F10 notification.
CDM principal designer vs Building Regulations principal designer
Since 1 October 2023, the Building Safety Act also created a Building Regulations principal designer and principal contractor, responsible for compliance with the Building Regulations. They are separate roles from the CDM ones, although the same firm often holds both.
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What does CDM mean?
Construction (Design and Management), the regulations that govern health and safety management on construction projects in Great Britain.
Does CDM apply to domestic jobs?
Yes. CDM 2015 applies to all construction work, including work for homeowners. The homeowner's client duties transfer to the contractor.
Do I need a construction phase plan for a one-week job?
Yes. Every project needs one, but it should be proportionate: a short plan is fine for small, low-risk work.
Checked against HSE guidance L153 and hse.gov.uk/construction/cdm, October 2026. Related: pre-construction information · F10 notification.