CDM 2015 Duties for Small Contractors: What You Actually Need to Do

The Construction (Design and Management) Regulations 2015 apply to virtually every construction project in the UK — including small domestic jobs and one-person operations. If you work in the trades, CDM 2015 almost certainly applies to you, yet it remains one of the most misunderstood pieces of legislation on site. This guide cuts through the confusion.

Does CDM 2015 Apply to Your Work?

Yes, almost certainly. CDM 2015 applies to all construction work, which the regulations define broadly to include building, alteration, fitting out, commissioning, renovation, repair, maintenance, decoration, and demolition. A sole trader re-roofing a house is caught by CDM 2015 just as much as a large principal contractor building a commercial unit.

The threshold questions are about which duties apply, not whether the regulations apply at all.

The Three Key Duty Holder Roles

CDM 2015 creates distinct roles with specific duties.

Client — the person or organisation commissioning the work. On domestic projects, most client duties transfer to the contractor or principal contractor by default.

Designer — anyone who prepares or modifies designs, including architects, structural engineers, and contractors who design temporary works or specify materials.

Contractor — anyone who carries out, manages, or controls construction work. This is where most tradespeople sit.

When there is more than one contractor on a project, the client must appoint a Principal Designer and a Principal Contractor. On smaller jobs with a single contractor, that contractor often takes on both contractor duties and, in practice, coordinates the work — though the formal PD/PC roles only become mandatory once a second duty holder is engaged.

What Contractors Must Do — The Core Duties

Regulation 15 sets out contractor duties. In plain terms, a contractor must:

• Plan, manage, monitor and coordinate the work under their control so it is carried out without risk to health or safety.
• Prepare a construction phase plan before work begins — even on small projects. This does not need to be lengthy, but it must be suitable and sufficient for the actual risks present.
• Not begin work on a site unless reasonable steps have been taken to prevent unauthorised access, particularly where there is a risk to members of the public.
• Ensure workers under their control have the skills, training, knowledge and experience to carry out their tasks safely.
• Provide workers with relevant parts of the construction phase plan and any site rules.
• Display the HSE's project notification (F10) on site where the project meets the notification threshold (more than 30 working days with more than 20 simultaneous workers, or exceeds 500 person-days).

The Construction Phase Plan: Keep It Proportionate

This is the document small contractors most often overlook or over-complicate. The HSE is explicit: the plan should be proportionate to the scale and complexity of the project and the risks involved.

For a straightforward domestic extension, a one or two page document covering the following is likely sufficient:

Critically, the construction phase plan is a live document. Update it if significant new risks emerge.

RAMS and CDM: How They Fit Together

A RAMS — a Risk Assessment combined with a Method Statement — is the standard way contractors document how specific tasks will be carried out safely. RAMS satisfy the risk assessment duty under the Management of Health and Safety at Work Regulations 1999 (reg 3) and also feed directly into the construction phase plan.

Think of it this way: the construction phase plan is the overarching site safety document; your RAMS are the task-level detail that sits beneath it. Both are required; neither replaces the other.

The Health and Safety File

On notifiable projects (or projects with a Principal Designer appointed), a health and safety file must be compiled and handed to the client at the end of the project. For small contractors working as the sole contractor on non-notifiable domestic work, this formal file is not required — but retaining records of what was built, what hazardous materials are present, and how the structure was constructed is still good practice and protects you commercially.

Common Mistakes Small Contractors Make

• Believing CDM only applies to large or commercial projects.
• Producing a construction phase plan once and never revisiting it.
• Confusing the Principal Contractor role with simply being the biggest company on site — it is a formal appointment.
• Assuming the domestic client exemption removes all duties. It does not; it only shifts certain client duties onto the contractor.
• Forgetting that subcontractors they engage become duty holders too — vetting their competence is part of your obligation.

Where to Find Authoritative Guidance

The HSE publishes Managing health and safety in construction: Construction (Design and Management) Regulations 2015 — Guidance on Regulations (L153). This is the approved code of practice and guidance and is the definitive reference for compliance questions. Reading it alongside a proportionate RAMS process gives small contractors a solid, defensible foundation.