CDM Regulations 2015: The Five Duty Holders Explained

Most construction and refurbishment work carries duties under CDM 2015 whether or not anyone involved thinks of it as a "construction project" — a homeowner having an extension built and a facilities manager commissioning office refurbishment can both end up holding legal duties they didn't know they'd taken on, simply by being the client.

The five duty holder roles

The Construction (Design and Management) Regulations 2015 assign specific duties to five roles rather than treating "the contractor" as solely responsible for site safety. Commercial clients must make suitable arrangements for managing the project, allocate sufficient time and resources, ensure other duty holders are appointed appropriately, and ensure welfare facilities are provided. Designers must eliminate, reduce or control foreseeable risks that could arise during construction and later maintenance, and pass on the information the rest of the project team needs. Principal designers plan, manage, monitor and coordinate health and safety through the pre-construction phase, ensuring designers meet their duties and liaising with the principal contractor. Principal contractors take on the equivalent role for the construction phase itself — planning, managing, monitoring and coordinating health and safety, preparing the construction phase plan, and organising cooperation between contractors. Contractors must plan, manage and monitor the construction work under their own control and follow directions from the principal designer or principal contractor on projects involving more than one contractor.

Why the client role catches people out

Anyone commissioning construction work is a client under CDM 2015, and that includes organisations that would never describe themselves as being "in construction." A business having an office fit-out, a school building a new classroom block, or a landlord commissioning refurbishment work are all clients with duties under the regulations — appointing competent designers and contractors, making sure they have the information they need, and ensuring the project is properly resourced and managed. The assumption that "we've hired a contractor, so it's their responsibility now" is one of the most common and consequential misunderstandings of how CDM 2015 actually allocates duties.

The domestic client exception

Domestic clients — people having construction work done on their own home that isn't connected to a business — are treated differently. Their duties as client don't disappear; they transfer to someone else in the project chain. On a single-contractor project, the client duties transfer to the contractor. On a project involving more than one contractor, they transfer to the principal contractor, or to the principal designer if one has been appointed in writing. This means a domestic client can commission work in good faith while the legal duties sit with the professionals they've engaged — but only if those roles are actually filled; an unclear or informal arrangement doesn't automatically create that transfer.

Pre-construction information and the construction phase plan

Two documents sit at the centre of how CDM 2015 actually gets applied day to day. Pre-construction information — details about the site, existing structures, hazards like asbestos, and any other relevant risk information — has to be provided to designers and contractors early enough to influence their planning, not handed over once work has already started. The construction phase plan, prepared by the principal contractor (or the contractor, on a single-contractor project), sets out how health and safety will be managed for the specific project, and has to exist before construction work begins, not be assembled retrospectively once questions get asked.

Where CDM 2015 compliance commonly breaks down

The most frequent gap isn't a missing construction phase plan on a large, obviously "constructiony" project — it's smaller refurbishment or fit-out work where nobody formally establishes who holds which duty, because the project didn't feel like "construction" in the way the regulations define it. Principal designer duties in particular are often left unassigned on projects with more than one contractor, leaving a genuine gap in who's coordinating pre-construction health and safety rather than that responsibility simply defaulting to somebody else.

FAQ

Does CDM 2015 apply to small refurbishment projects, not just large builds?
Yes. CDM 2015 applies to construction work generally, including refurbishment, fit-out, and demolition, not only large new-build projects. The size of the project affects which specific duties apply, not whether the regulations apply at all.

Who is the "client" under CDM 2015?
Anyone for whom a construction project is carried out, including businesses commissioning work that isn't in the construction industry themselves — an office fit-out client is still a client under the regulations.

What happens to a domestic client's duties?
They transfer to the contractor on a single-contractor project, or to the principal contractor (or principal designer, if appointed in writing) on a project with more than one contractor.

Is the construction phase plan only needed for large sites?
No. A construction phase plan is required for construction work generally and must be in place before work starts, proportionate to the size and risk of the project.

CDM 2015's biggest practical risk isn't non-compliance on projects that obviously look like construction — it's smaller or less obvious projects where nobody formally establishes who holds which duty. Learnsignal's guide to working at height and the hierarchy of control covers a hazard category that features heavily on the construction sites CDM 2015 governs. Browse our CPD courses to build CDM 2015 awareness into your team's compliance training.