Who Is Responsible for the Construction Phase Plan? Client, PD, PC and Contractor Roles Explained

If you’re asking “who is responsible for the construction phase plan?”, you’re usually trying to answer two separate questions:

• Who must make sure a CPP is in place before work starts?
• Who actually puts the plan together and keeps it working on site?

Under CDM 2015, responsibility is shared across duty holders—but it isn’t vague. The rules set clear expectations for the client, principal designer (PD), principal contractor (PC) and contractors, and those expectations shift depending on whether the job has one contractor or several, and whether the PC changes mid‑project.

What the Construction Phase Plan is (in one sentence)

The Construction Phase Plan (CPP) is the project’s live health and safety management plan for the construction phase—setting out how you’ll plan, manage and monitor the work, coordinate contractors, and control the main risks.

For wider context on the legal framework, see our guide to the cdm regulations.

So, who is responsible for the Construction Phase Plan?

In practice, the Principal Contractor is typically responsible for preparing (and maintaining) the Construction Phase Plan for projects involving more than one contractor.

However, the client is responsible for ensuring that a CPP is in place before construction work starts. The client does not usually write the CPP, but must make sure the arrangements exist for it to be produced and used.

Quick responsibility check (typical multi‑contractor project)

Duty holder	What they’re responsible for (CPP-specific)	What “good” looks like in practice
Client	Ensuring a CPP is in place before construction starts; ensuring suitable management arrangements are made	Confirms a PC is appointed (where required), sets pre-start information expectations, checks the CPP exists and is suitable for the job before mobilisation
Principal Designer (PD)	Design-phase risk management and coordination; supports information flow that informs the CPP	Ensures key design risks, residual hazards and sequencing implications are identified and communicated in time for planning construction controls
Principal Contractor (PC)	Preparing, implementing and updating the CPP; planning, managing and monitoring construction work	Produces a CPP that matches the scope, coordinates contractors, sets site rules/arrangements, updates it as the plan changes
Contractors	Following the CPP and providing information needed to plan and coordinate their work	Feed in sequencing, interfaces, plant/material risks, and cooperate with site arrangements (welfare, traffic, supervision, etc.)

Who must ensure a CPP exists before work starts?

The client must ensure a Construction Phase Plan is in place before the construction phase begins. That does not mean the client has to draft it line-by-line. It means the client must set up the project so that:

• there is a clearly identified party producing the CPP (typically the PC on multi‑contractor projects),
• the CPP is available before people start work, and
• the CPP is appropriate to the scope and risks (not a generic document that ignores what’s actually happening on site).

Who prepares the CPP on small jobs?

On a single‑contractor job (where there is no Principal Contractor appointment because only one contractor is involved), the contractor doing the work will normally prepare the Construction Phase Plan (often proportionate and short for low‑risk, short-duration work).

The client’s role doesn’t disappear: the client should still ensure that a CPP exists before work starts, even if that CPP is produced by the sole contractor.

Multi‑contractor sites: how responsibility works in the real world

Where more than one contractor will be involved (whether at the same time or in sequence), CDM 2015 usually requires the appointment of:

• a Principal Designer (to coordinate health and safety in the pre‑construction phase), and
• a Principal Contractor (to plan, manage and monitor the construction phase).

In this scenario, the CPP is generally a PC-owned document, because the PC controls (or must control) construction-phase coordination: access, inductions, welfare, site rules, temporary works coordination, interface management, and supervision.

Key point: the CPP should act as the site management system in writing—not a one-off “startup pack”. If the programme, sequencing, subcontractors or site constraints change, the CPP should evolve.

What changes when the Principal Contractor changes mid‑project?

If the PC changes (for example, termination, novation, insolvency, or re-procurement), responsibility for the CPP shifts with control of the construction phase.

Practical expectation

• The incoming PC should take ownership of the CPP going forward—reviewing what exists, verifying it reflects current reality, and issuing an updated version under their control.
• The outgoing PC should hand over relevant information (what’s been built, what remains, what risks are live, what systems are operating).
• The client should ensure there is no gap: there must be a CPP in place and a competent organisation in control before work continues.
• The PD should ensure design-risk information and coordination continue so that construction planning stays aligned with design decisions and changes.

Practical handover: what to document to show decisions and control are in place

Whether you’re moving from pre-start into mobilisation, onboarding additional contractors, or changing PC, the aim is simple: show who is in control, what the plan is, and how it will be kept current. The following documentation points are practical, audit-friendly evidence that responsibilities are understood and managed.

1) Role and appointment clarity

• Written confirmation of who the client is (including where there are domestic/client-agent arrangements).
• Formal appointment records for PD and PC (where required) and the scope of their appointment.
• A simple responsibility map showing who does what for: inductions, welfare, traffic routes, temporary works, permits (if used), and contractor coordination.

2) CPP version control and ownership

• A clearly marked CPP owner (usually the PC), version number, issue date, and distribution list.
• A change log noting what changed and why (programme, sequencing, site constraints, design change, incident/learning).
• Evidence of communication: briefings, inductions, supervisor updates, and how changes are cascaded to contractors.

3) Interface and sequencing decisions

• Key sequencing assumptions (what must happen before what, and why).
• Contractor interface controls (shared work areas, simultaneous operations, deliveries, exclusion zones, lifting operations coordination where relevant).
• Access/egress plan and traffic management arrangements aligned to the site constraints.

4) Information that should feed the CPP (and stay aligned)

• Pre-construction information that impacts the build (constraints, existing services, asbestos information where applicable, occupancy constraints, neighbours/public interface).
• Design risk information from the PD: residual risks, unusual sequences, and any assumptions requiring contractor confirmation.
• Welfare arrangements and site set-up plan (proportionate to the work).

5) Demonstrating ongoing control

• Inspection and monitoring routines (site checks, housekeeping, access control, contractor coordination meetings as appropriate).
• How competence is managed for site activities (e.g., supervisors, plant operators) without relying on generic statements.
• How incidents, near misses and learning trigger CPP updates (and who approves the change).

Common misunderstandings (and the practical fix)

• “The PD is responsible for the CPP.” The PD influences what must be planned for (design risks and pre-construction coordination), but the CPP is typically owned and run by the PC during construction.
• “The client can delegate everything.” The client can appoint others to do tasks, but must still ensure arrangements exist—especially that a CPP is in place before work starts.
• “A CPP is the same as RAMS.” They link, but they are not the same: the CPP sets the overarching site management arrangements; task methods sit underneath and must align with it.
• “One CPP works for every job.” A CPP must reflect the specific site, sequencing and interfaces. Generic content is a red flag if it doesn’t match reality.

FAQs

Who is legally responsible for ensuring there is a construction phase plan?
The client is responsible for ensuring a Construction Phase Plan is in place before construction work starts. In practice this means the client must set the project up so the CPP is produced on time, is suitable for the work, and is actually used to manage the construction phase.

 

Who normally writes the construction phase plan?
On projects with more than one contractor, the Principal Contractor normally prepares and maintains the CPP because they control construction-phase coordination. On single‑contractor projects, the contractor carrying out the work will usually produce a proportionate CPP.

 

Does the Principal Designer have to approve the construction phase plan?
The PD’s core role is to plan, manage and monitor the pre‑construction phase and coordinate design risk management. While the PD should provide information that shapes construction planning (and may review for alignment), the CPP is primarily a construction-phase management document owned by the PC.

 

What happens if construction starts without a CPP?
If work starts without a CPP, the project is missing the documented arrangements for managing the construction phase. Practically, that creates gaps in coordination (welfare, access, traffic, inductions, sequencing and interfaces). The immediate fix is to stop and establish a proportionate CPP and communicate it before continuing.

 

If the Principal Contractor changes, can the new PC use the old CPP?
The incoming PC can use existing material as an input, but they should reissue the CPP under their ownership after review—so it reflects current site conditions, scope, contractor set-up and the new PC’s management arrangements. The client should ensure there is no period where work continues without an active, owned CPP.

 

How detailed does a construction phase plan need to be?
It should be proportionate to the work, risks and complexity. A small, low‑risk job may need a short CPP focused on the essentials (site set-up, welfare, access, supervision, key risks). A complex, multi‑contractor project needs more detail on coordination, interfaces, sequencing, and how the plan is monitored and updated.

Summary and next step

Responsibility for the Construction Phase Plan is shared, but not unclear: the client must ensure a CPP is in place before work starts, and the Principal Contractor will typically prepare, implement and maintain it on multi‑contractor projects (with the PD supplying design-risk information that must be planned for). Responsibility should be backed by clear appointments, version control, and documented handovers—especially when the PC changes.

How we can help: If you want a second set of eyes on whether your project documentation shows clear control (appointments, information flow and a live CPP), explore our practical guidance across the CDM regulations and align your project set-up before mobilisation.

Disclaimer

This resource is provided as a template for general guidance only. It must be reviewed, adapted, and approved by a competent person before use. No warranty or guarantee is given or implied regarding completeness, accuracy, or compliance. Use of this resource is at your own risk.