CDM 2015 Explained: What Every Construction PM Needs to Know

The Construction (Design and Management) Regulations 2015 — commonly known as CDM 2015 — are the primary regulatory framework governing health, safety and welfare on UK construction projects. They came into force on 6 April 2015, replacing CDM 2007, and apply to virtually every construction project in the country. For a construction project manager, CDM 2015 isn't just a compliance box to tick. It's the framework that defines who is responsible for what, when, and how.

Who does CDM 2015 apply to?

CDM 2015 applies to all construction work, though the extent of duties depends on whether a project is notifiable — meaning it will last more than 30 working days with more than 20 workers working simultaneously, or exceed 500 person-days of construction work. Notifiable projects require an F10 notification to the HSE and the appointment of a Principal Designer and Principal Contractor.

Even for non-notifiable projects, CDM 2015 still imposes duties on clients, designers and contractors. The scale of compliance requirements increases with the scale and complexity of the project.

The key duty holders

The Client has overarching duties, including ensuring suitable arrangements are in place for managing the project and that sufficient time and resources are allocated. On most commercial projects, the client appoints a project manager or client representative to discharge these duties.

The Principal Designer is responsible for planning, managing, monitoring and coordinating the pre-construction phase. They must ensure all designers cooperate and that health and safety is considered throughout design. This role is frequently misunderstood — it is not simply about design, but about coordinating health and safety across the entire pre-construction phase.

The Principal Contractor takes over once construction begins. They plan, manage and monitor the construction phase, including producing and maintaining the Construction Phase Plan and ensuring all contractors cooperate with each other.

The three key documents

Three documents sit at the heart of CDM 2015 compliance.

• Pre-Construction Information — compiled by the Principal Designer and provided to all designers and contractors before construction begins.
• Construction Phase Plan — prepared by the Principal Contractor before construction starts and updated throughout the project.
• Health and Safety File — compiled throughout the project and handed to the client at completion, recording information needed for future maintenance, alteration or demolition.

Common failure points

In our experience, the most common CDM failures are not dramatic — they're administrative. The F10 not submitted or not updated. The Construction Phase Plan accepted but never reviewed. RAMS signed off but not checked against actual work on site. Site inductions completed but records not kept.

The solution is a systematic approach to compliance checks — not a last-minute scramble before an audit. Monthly CDM site checks, a running action log and a habit of documenting everything are the habits that keep projects compliant and project managers protected.