Skip to main content
The Site Book
Start free

Construction compliance guide

What is a Construction Phase Plan?

A plain-English guide to CPPs for UK builders. What they are, who needs one, what goes in them, and how to create one without losing your mind.

What is a CPP?

A Construction Phase Plan (CPP) is a document that sets out how health and safety will be managed during the construction phase of a project. It is required under Regulation 12 of the Construction (Design and Management) Regulations 2015 — commonly known as CDM 2015.

Think of it as your game plan for keeping people safe on site. It is not a risk assessment (that is a separate thing), and it is not a method statement. The CPP sits above those documents and describes the overall approach to managing health and safety across the whole project — from the first day on site to the final snagging visit.

The CPP must be drawn up before the construction phase begins. You cannot start work and then write it afterwards — that defeats the purpose. The whole point is that you have thought about the risks and put arrangements in place before anyone picks up a tool.

Who needs a CPP?

Every construction project in Great Britain needs a Construction Phase Plan. There is no minimum size threshold, no exemption for domestic work, and no get-out for sole traders. If you are doing construction work, you need a CPP.

The responsibility for producing the CPP depends on how the project is structured:

  • More than one contractor on site: The principal contractor must produce and maintain the CPP.
  • Only one contractor on site: That contractor must produce the CPP. This is the most common scenario on domestic jobs.

If you are a sole trader fitting a kitchen, you need a CPP. If you are a two-person firm building an extension, you need a CPP. If you are a principal contractor managing a commercial fit-out with five subcontractors, you need a CPP. The scale and detail of the plan will differ, but the requirement is universal.

When is a CPP required?

The CPP must be prepared before the construction phase begins. CDM 2015 is explicit about this — you cannot start construction work until a plan is in place. In practice, that means you should be writing your CPP during the planning and preparation stage, after you have won the job but before the first day on site.

The CPP is also a living document. It should be reviewed and updated as the project progresses, especially if conditions change, new risks emerge, or additional contractors come on site. A CPP written on day one and never looked at again is not meeting the spirit of the regulations.

Domestic vs commercial projects

CDM 2015 makes an important distinction between domestic and commercial clients, but it does not exempt domestic projects from compliance. Here is how it works:

A domestic client is someone having construction work done on their own home (or the home of a family member) that is not connected to a business. Under CDM 2015, domestic clients do not have to carry out client duties themselves. Instead, those duties transfer automatically to the contractor. If there is one contractor, they get all the client duties. If there is a principal contractor, the duties transfer to them.

What this means in practice: on a domestic job, you cannot say “the homeowner should have sorted that out.” The compliance responsibility is yours. You need to produce the CPP, manage site safety, and make sure welfare facilities are in place.

On commercial projects, the client retains their CDM duties and is expected to appoint a principal designer and principal contractor (if more than one contractor is involved), provide pre-construction information, and ensure adequate welfare facilities. The CPP is typically more detailed for commercial work, reflecting the greater complexity and number of parties involved.

What goes in a CPP?

CDM 2015 does not prescribe a rigid format, but it does set out the information that a CPP must include. Here are the key sections you need to cover:

Project description

What the work involves, the site address, expected duration, and the names of key people (client, principal designer, principal contractor, or sole contractor).

Management structure

Who is responsible for what on site. On a domestic job with one contractor, this can be straightforward — you are responsible for everything. On a multi-contractor project, you need to set out the chain of responsibility.

Site rules

The rules that everyone on site must follow. This covers things like PPE requirements, working hours, smoking areas, parking, deliveries, and site access.

Arrangements for managing key risks

How you will deal with the main health and safety risks on the project. This does not need to duplicate your RAMS — it is about the overarching arrangements, such as how you will manage working at height, demolition, temporary works, or hazardous materials.

Welfare facilities

What welfare provisions are in place for workers. This includes toilets, washing facilities, drinking water, rest areas, and somewhere to change and store clothing. On domestic jobs, the homeowner’s facilities are often used by agreement.

Monitoring and review

How you will check that the plan is being followed and what happens if things change. This is about making sure the CPP is a living document, not something that gets filed and forgotten.

How The Site Book creates your CPP automatically

Writing a CPP from scratch is tedious. You know what you are doing on site, but translating that into a formal document takes time you would rather spend on the tools. That is exactly why we built The Site Book.

For domestic projects, the Lightweight CPP wizard asks you just 4 plain-English questions about your job. It then takes your answers and creates a professional, site-specific Construction Phase Plan — typically 1–2 pages — covering all the sections required under CDM 2015. You review it, make any tweaks, and download a branded PDF. The whole process takes under 5 minutes.

For commercial projects, the full CPP wizard guides you through a 6-step process: project basics, site information, personnel, works description, hazards, and a final review. It pre-fills as much as possible from your project description and site data, so you are reviewing and approving rather than writing from scratch.

Either way, you end up with a document that is tailored to your specific project, covers the legal requirements, and is ready to hand to your client, principal designer, or an HSE inspector.

Frequently asked questions

Common questions builders ask about Construction Phase Plans.

Do I need a CPP for a kitchen extension?

Yes. CDM 2015 applies to all construction work in Great Britain, and that includes domestic projects like kitchen extensions, loft conversions, bathroom refurbishments, and garage conversions. As the contractor on a domestic job, you are legally required to produce a Construction Phase Plan before work begins on site. The good news is that for a straightforward domestic project, your CPP does not need to be a 20-page document. A proportionate, 1–2 page plan covering the key risks, management arrangements, and welfare provisions is perfectly acceptable. The Site Book’s Lightweight CPP wizard is built exactly for this — answer 4 simple questions about your job, and get a professional, compliant plan in minutes.

Who is responsible for the CPP?

The responsibility for producing and maintaining the Construction Phase Plan depends on the project structure. If there is more than one contractor on the project, the principal contractor must draw up the CPP. If you are the only contractor on site — which is common on domestic jobs — then you are responsible for the CPP as the ‘only contractor’. On domestic projects, the homeowner (the client) does not take on CDM client duties; those duties transfer automatically to the contractor or principal contractor. This means you cannot rely on the homeowner to sort out compliance — it falls squarely on you.

What happens if I don’t have a CPP?

If you carry out construction work without a suitable and sufficient Construction Phase Plan, you are in breach of CDM 2015. The Health and Safety Executive (HSE) can take enforcement action, which may include issuing an improvement notice requiring you to produce a CPP within a set timeframe, issuing a prohibition notice that stops work on site until you comply, or prosecuting you. Fines for CDM breaches can be significant — and a prosecution stays on your record. Beyond the legal consequences, not having a CPP means you have not properly thought through the risks on your project, which increases the chance of someone getting hurt. It also leaves you exposed if there is an incident and the HSE investigates.

Can I write my own CPP?

Absolutely. There is no legal requirement to hire a consultant to write your Construction Phase Plan. You can — and should — write it yourself, because you are the person who understands the job best. The key requirement is that the CPP must be ‘suitable and sufficient’ for the project. That means it needs to cover the actual risks on your specific site, describe how you will manage health and safety, and set out welfare arrangements. A generic template that you have not tailored to the project will not meet the legal standard. The Site Book helps by guiding you through the process step by step and pre-filling sections from your project description, so you end up with a site-specific document without staring at a blank page.

How long should a CPP be?

There is no fixed length requirement. The CPP should be proportionate to the size, complexity, and risk level of the project. For a straightforward domestic job — a kitchen extension, a bathroom refit, a loft conversion — a well-written 1–2 page plan is usually sufficient. For larger commercial projects with multiple contractors, significant hazards, and complex logistics, the CPP will naturally be longer and more detailed. The HSE has explicitly stated that a CPP does not need to be a lengthy document — what matters is that it is relevant, site-specific, and actually used on the job. A 50-page document that sits in a drawer is worth less than a 2-page plan that everyone on site has read and understands.

Create your CPP in minutes

Now you know what a CPP is — let The Site Book create yours. Describe the project, we write the plan.

See how it works →

Ready to create yours?

Stop wrestling with blank templates. Describe your project and get a CDM 2015 compliant Construction Phase Plan in minutes.

Try our free CPP generator →

Related guides

CDM 2015 for Small Builders

Your duties under CDM 2015, explained without the jargon.

What is RAMS?

A builder’s guide to Risk Assessments and Method Statements.

Site Inductions Guide

What to cover, how to run one, and why digital beats paper.

Get a free CPP template emailed to you

No spam. Just the free resource. Unsubscribe any time.

Create your CPP in under 5 minutes.

Describe your job, answer a few questions, and get your Construction Phase Plan. Free trial — no credit card required.

Start free trialBack to guides