Construction Phase Plan UK — What It Is, Who Writes It and What It Must Include (2026)

If you carry out construction work in the UK, you almost certainly need a construction phase plan (CPP). It is a legal requirement under the Construction (Design and Management) Regulations 2015 — better known as CDM 2015 — and it must be in place before any construction work starts on site.

Many tradespeople confuse the CPP with a health and safety policy, or assume it only applies to large commercial sites. Neither is true. A small domestic extension with a single contractor still requires one. This guide explains exactly what the plan is, who writes it, what it must contain, and the real consequences of not having one.

What is a construction phase plan?

A construction phase plan is a document that sets out how health and safety will be managed during the construction phase of a project. It is not a policy statement, a risk assessment or a method statement — though it will reference or incorporate all of those. It is the overarching plan for how work on that specific site will be carried out safely.

The legal basis is Regulation 12 of CDM 2015, which requires the contractor (or Principal Contractor on multi-contractor sites) to prepare the CPP before the construction phase begins. The plan must be specific to the project — generic, cut-and-paste documents that bear no relation to the actual site risks are not compliant, and an HSE inspector will spot them immediately.

The CPP is distinct from a health and safety policy. A health and safety policy describes your general approach to managing health and safety across your business. The CPP is project-specific: it tells anyone who needs to know how this job, on this site, with these risks, will be managed safely from start to finish.

When is a construction phase plan required?

Under CDM 2015, a construction phase plan is required for all construction projects — not just notifiable ones. This is one of the most common misunderstandings among sole traders and small contractors.

Even a small domestic extension, a bathroom refurbishment, or a garden drainage job technically requires a CPP. The key word in the regulations is "proportionate": the level of detail in your plan should reflect the complexity and risk of the project. A one-contractor domestic job does not need the same 30-page document as a commercial fit-out with ten subcontractors — but it still needs something in writing.

The HSE is clear on this point. The question is never whether you need a CPP, but how detailed it needs to be. For a straightforward low-risk job, two to four pages covering the main hazards is usually sufficient.

Who writes the construction phase plan?

Responsibility for writing the CPP depends on the structure of your project:

• Single contractor (including sole traders with no employees): You write your own plan. Even if you are a one-person business doing domestic work, you are responsible for producing the CPP for your project.
• Multiple contractors on site: A Principal Contractor must be appointed, and it is the Principal Contractor's responsibility to write and maintain the CPP. It covers all contractors working on site, not just the main firm.
• Where a Principal Designer has been appointed: The Principal Designer is responsible for gathering and providing pre-construction information — information about the site, existing hazards and design decisions that affect health and safety. This information must feed into the CPP. The Principal Designer writes the pre-construction information pack; the Principal Contractor turns it into the CPP.

On most domestic jobs carried out by a single trade, the homeowner is the client and no Principal Designer is formally appointed. In that case, you as the contractor write the plan, and you should ask the client (or their architect, if there is one) for any relevant information about the property before starting work.

Notifiable projects and the F10 notification

Some projects are classified as "notifiable" under CDM 2015 and must be reported to the HSE before work begins. A project is notifiable if it is likely to:

• Last more than 30 working days with more than 20 workers simultaneously on site at any point, or
• Exceed 500 person-days of construction work in total.

For notifiable projects, the client must submit an F10 notification to the HSE using the HSE's online portal. This must be done before the construction phase starts and should be displayed on site once submitted.

Critically, the F10 notification does not replace the construction phase plan — it is a separate requirement. And as explained above, non-notifiable projects still require a CPP. The notifiability threshold only determines whether you need to tell the HSE the project is happening; it does not change your obligation to plan for safety.

On notifiable projects, a Principal Contractor and Principal Designer must both be appointed in writing by the client. These are formal CDM duty-holder roles, not informal arrangements.

What a construction phase plan must contain

Schedule 3 of CDM 2015 sets out the required contents of a construction phase plan. At a minimum, your plan should cover:

• Project description: What is being built or altered, the site address, approximate timescales, and a brief description of the scope of work.
• Management structure and responsibilities: Who is the client, who is the Principal Contractor (if applicable), who holds day-to-day responsibility for health and safety on site, and how decisions are escalated.
• Arrangements for controlling significant site risks: This is the core of the document. It should address the specific risks present on this site — working at height (scaffolding, ladders, roof access), excavations and ground conditions, vehicle movements, COSHH hazards (dust, solvents, lead paint, asbestos), manual handling, electrical systems, noise and vibration, and any other hazards identified during planning.
• Welfare arrangements: Where are the toilets? Where can workers wash their hands? Is there somewhere to rest and eat? These must be confirmed before work starts — they cannot be an afterthought.
• Emergency procedures: What happens if someone is injured? What is the nearest hospital with A&E? Who is the first aider on site? What is the evacuation procedure if the site needs to be cleared?
• How pre-construction information will be used: If the client or Principal Designer has provided information about the site (asbestos surveys, utility drawings, ground investigation reports, structural information), your plan should reference it and explain how it has shaped your approach to managing risk.

For multi-contractor sites, the CPP should also include site induction arrangements, site rules, subcontractor management procedures, and how information will be communicated across the workforce.

Proportionality: small jobs vs large sites

The HSE explicitly states that the CPP should be proportionate to the scale and complexity of the project. Do not let this become bureaucracy for its own sake — the document should be usable on site, not filed in a drawer and forgotten.

Small domestic project (1–2 contractors, low risk): A two-to-four page document is typically sufficient. It should identify the main risks for that specific job (for example, working on a roof, cutting through a floor, or working near an existing electrical installation), set out the welfare arrangements, and confirm the emergency procedure. It can be handwritten or produced from a simple template, as long as it is specific to the job.

Commercial fit-out or multi-contractor site: Expect a document of 20–30 pages or more, covering subcontractor appointments, permit-to-work systems, site induction records, a traffic management plan, method statements for high-risk activities, COSHH schedules, and a comprehensive emergency plan. Main contractors will ask to see this before allowing you on site.

The test is simple: could someone unfamiliar with the project pick up your CPP and understand how health and safety is being managed? If not, it needs more work.

Keeping the plan live and updated

A construction phase plan is not a one-off document produced before the job starts and then never looked at again. CDM 2015 requires it to be reviewed and updated as the project progresses.

If circumstances change — unexpected asbestos is found during demolition, a new subcontractor comes onto site, the structural scope changes, bad weather creates new ground hazards — the CPP must be updated to reflect the new risks and the revised controls. Keep a record of when updates were made and confirm that all relevant workers were briefed on the changes.

On larger sites, a version-controlled log of CPP revisions is standard practice. On smaller domestic jobs, a simple note of the date and nature of any update, signed by the contractor, is usually sufficient. The point is that the document remains an accurate reflection of how the site is actually being managed at any given time.

Pre-construction information from the client

Before you write your CPP, you should ask the client — and their architect or designer if there is one — for pre-construction information about the site. This is a formal requirement under CDM 2015: the client has a duty to provide information they hold or can reasonably obtain.

Relevant pre-construction information includes:

• Asbestos surveys or management plans (mandatory for properties built before 2000)
• Ground investigation or contamination reports
• Utility drawings showing the location of gas, electricity, water and drainage services
• Existing structural drawings or engineer's reports
• Information about hazardous materials (lead paint, PCBs, biological hazards)
• Previous construction or alteration records

Do not start work without asking for this information. If the client says they have nothing, make a note of that in your CPP. If you discover something unexpected on site — a hidden asbestos-containing material, an uncharted service, unstable ground — stop work, reassess, and update your plan before continuing.

Consequences of not having a construction phase plan

Failing to produce a CPP — or producing one that is clearly generic and not site-specific — carries real consequences:

• HSE enforcement action: An HSE inspector can issue an improvement notice requiring you to produce a compliant plan within a set timeframe, or a prohibition notice stopping all work on site immediately if they believe there is a risk of serious injury.
• Prosecution: CDM 2015 breaches can result in prosecution under the Health and Safety at Work Act 1974. Fines for contractors can run to tens of thousands of pounds, and in serious cases, directors can face personal liability.
• Exclusion from commercial sites: On any commercial project, the main contractor or principal contractor will request your CPP before allowing your team on site. Without one, you will not be given access. This is increasingly standard practice even on mid-sized domestic projects managed by professional clients.
• Insurance implications: Some clients' and employers' liability insurers require evidence of CDM compliance as a condition of cover. A claim arising from a site where no CPP was in place could be contested.

The good news is that for most small domestic jobs, producing a basic but genuine CPP takes less than an hour. The risk of not doing it — to your workers, your business and your licence to operate — is vastly greater than the time it takes to write one.