Practical construction guide

Principal contractor duties under CDM 2015

The principal contractor coordinates the construction phase where a project involves more than one contractor. The appointment is not simply a name on the construction phase plan: it requires active planning, management, monitoring and coordination of the work.

Reviewed 14 September 2026 · By Lloyd Godsall

When is a principal contractor required?

Where a construction project involves, or is likely to involve, more than one contractor, the client must appoint a principal contractor in writing. The appointment should be made as soon as practicable and before the construction phase begins. On a single-contractor project there is no principal contractor; the contractor carries the relevant construction-phase planning duties.

Core principal contractor duties

The principal contractor must plan, manage, monitor and coordinate health and safety during the construction phase. In practical terms, that means establishing arrangements that work across the project rather than checking each contractor in isolation.

Liaise with the client and principal designer and use relevant pre-construction information
Prepare, implement and keep the construction phase plan under review
Organise cooperation between contractors and coordinate their work
Check that appointed contractors have the necessary skills, knowledge, experience and organisational capability
Provide suitable site inductions and project information
Take reasonable steps to prevent unauthorised access
Provide and maintain suitable welfare facilities from the start
Consult and engage workers on matters affecting their health, safety and welfare
Provide suitable site-specific rules, supervision and management arrangements

What should the evidence look like?

The evidence should follow the decisions being made. Useful records may include appointments, project and design-risk reviews, competence checks, the live construction phase plan, contractor RAMS reviews, inductions, coordination meetings, inspections, worker consultation, change controls and closeout of actions. Large volumes of disconnected paperwork are not a substitute for control.

A useful assurance test

Can the project show who is coordinating each significant interface, what information they used, what was decided, who owns the action and whether the control is working on site?

Common gaps to look for

The principal contractor is appointed late or the role is unclear
The construction phase plan is generic or is not updated as the work changes
Contractor RAMS are collected but interfaces between trades are not coordinated
Temporary works, design changes or services information have no clear control route
Inductions describe rules but do not address the project-specific risks
Welfare, public protection, traffic or emergency arrangements are left until mobilisation
Workers are briefed but there is no meaningful route for consultation or feedback
Inspections identify issues without named actions, deadlines or verification of closeout

Official guidance

HSE summarises the principal contractor role and the wider CDM dutyholder responsibilities in its CDM 2015 dutyholder summary. The supporting legal guidance is Managing health and safety in construction (L153).

For help reviewing the project arrangements, see CDM support and the construction phase plan guide.