15th June, 2023

9 Principal Contractor Facts (And 3 Myths)

The principal contractor is a role required under CDM on every construction project with more than one contractor. Since most construction projects need a principal contractor, let's take a look at some facts (and myths) about this CDM role.

9 Principal Contractor Facts (And 3 Myths) header image

The principal contractor is a legal requirement on nearly every construction project. If your project has more than one contractor working on it (at any time), it needs a principal contractor.

But what is a principal contractor?

If you're short on time and need to know some quicks facts (and the common myths) about principal contractors - you're in the right place.

Here are our nine quick facts about the principal contractor:

  1. Legally required under CDM ✅
  2. Is a contractor ✅
  3. Required on any projects with more than one contractor ✅
  4. Appointed by the client ✅
  5. Appointed in writing ✅
  6. In control of the construction work ✅
  7. Has overall responsibility for health and safety during construction ✅
  8. Has extra CDM duties ✅
  9. Must be competent ✅

And three common myths:

  1. Only required on notifiable projects ❌
  2. Not required on residential projects ❌
  3. Is the same as the main contractor ❌

1. The principal contractor is legally required under CDM

✅ FACT

The Construction (Design and Management) Regulations apply to all construction projects, and it is within this set of regulations you will find the legal definition of the principal contractor.

“principal contractor” means the contractor appointed under regulation 5(1)(b) to perform the specified duties in regulations 12 to 14;

The Construction (Design and Management) Regulations 2015 Interpretation

This definition simply tells us that the principal contractor:

So let's dive deeper.

2. The principal contractor is a contractor

✅ FACT

Ok, this really is a quick fact. But the clue is the name. Principal contractor.

The principal contractor is a contractor.

“contractor” means any person (including a non-domestic client) who, in the course or furtherance of a business, carries out, manages or controls construction work;

The Construction (Design and Management) Regulations 2015 Interpretation

And since the principal contractor is the contractor in control of the construction phase, they fit nicely into that definition of a contractor.

3. The principal contractor is required on any project with more than one contractor

✅ FACT

The principal contractor is needed on any construction project with more than one contractor.

If a construction project has only one contractor, then a principal contractor is not necessary, but the single contractor will have some extra duties under CDM instead.

Most construction projects have more than one contractor, so a principal contractor is needed more often than you might think. If you have a scaffolder and roofer, for example, you need a principal contractor. If you have a plumber and an electrician, you need a principal contractor.

The principal contractor is appointed under regulation 5(1)(b).

5.—(1) Where there is more than one contractor, or if it is reasonably foreseeable that more than one contractor will be working on a project at any time, the client must appoint in writing—

  1. a designer with control over the pre-construction phase as principal designer; and
  2. a contractor as principal contractor.

This tells us that the principal contractor is appointed by the client, on any project with more than one contractor. And that the appointment must be made in writing.

And that gives us our next two principal contractor facts!

4. The principal contractor is appointed by the client

✅ FACT

The principal contractor doesn't appoint themselves. Apart from on domestic projects, the principal contractor must be appointed by the client.

The client should be aware that even if they only pay a single contractor, if that contractor uses subcontractors, they still need to appoint a principal contractor.

For example, you decide to have a refurbishment and give the job to a single contractor responsible for all the work. If they hire an electrician and a scaffolder as subcontractors, it becomes a multi-contractor project, and a principal contractor is required. In this case, it would make sense for the refurbishment contractor to also be appointed as the principal contractor.

5. The principal contractor must be appointed in writing

✅ FACT

The principal contractor must be appointed in writing by the client. The regulations specifically require a written appointment.

5.—(1) Where there is more than one contractor, or if it is reasonably foreseeable that more than one contractor will be working on a project at any time, the client must appoint in writing

  1. a designer with control over the pre-construction phase as principal designer; and
  2. a contractor as principal contractor.

6. The principal contractor is in control of the construction work

✅ FACT

Traditionally, construction projects have a main contractor. And usually, the main contractor will be the principal contractor.

If your construction project is set up in this way, with a main contractor and several subcontractors, then appointing the principal contractor can be done at the same time as picking your main contractor. You can appoint both roles together.

But not every construction project structure works this way.

Sometimes, a developer might be the client. And they will carry out most of the work themselves but use subcontractors for specialist works like gas, electrics, roofing etc. In this case, they are both the client and a contractor. The developer can be both the client and the principal contractor.

If instead, the client is just appointing subcontractors, and is not involved in the construction work, or management of the work, during the build, they will need to choose a contractor as the principal contractor. You can't have two principal contractors, so if no contractor is in overall control, you may need a project manager or additional contractor to take on that responsibility to comply with CDM.

Or you might have a design and build contract. In this situation, the principal contractor might also be the principal designer on the project.

The principal contractor will need to be present on the site (most of the time) because they have several responsibilities they need to carry out.

7. The principal contractor has overall responsibility for health and safety during construction

✅ FACT

A construction project is usually a team project, and the principal contractor is the leader of that team.

The principal contractor is the contractor with overall responsibility for health and safety on the project. They are in charge of the site, and plan how best to manage the work and all the other contractors, to get the work done safely.

The principal contractor isn't the only contractor with health and safety responsibilities. Every contractor on the project has health and safety responsibilities.

But if each contractor only considers their own safety, they might put other workers at risk on the project.

electrician working on socket

For example, they might power up a new electrical system when their work is completed, not realising another contractor's work is still in progress and assuming the system is dead.

And if each contractor only worries about what they need to work safely, then resources could run out for other contractors.

For example, they might order a small skip for their waste, taking up the space needed for a larger skip required by another contractor, leading to a build-up of waste on the site.

From these examples, we can see why it's important to have a principal contractor in overall control of the site to manage contractors, safety, resources and communication on the project.

8. The principal contractor has extra CDM duties

✅ FACT

In addition to CDM contractor duties, the principal contractor has some extra health and safety responsibilities under CDM.

These responsibilities include:

Contractors still have health and safety requirements, but the principal contractor needs to have extra planning and monitoring to make sure that risks are communicated and managed between the different contractors.

The principal contractor will prepare a construction phase plan, which outlines the health and safety plan for the project. This plan is provided to each contractor to tell them what the plan is for the project.

All contractors must report to the principal contractor, and obey the site rules and requirements put in place by the principal contractor.

The principal contractor will make sure that each contractor is inducted and follows the construction phase plan.

Find out more about the principal contractor role and responsibilities in CDM 2015 Principal Contractor Duties Explained.

9. The principal contractor must be competent

✅ FACT

The principal contractor is no longer a contractor who is just responsible for the health and safety of their own team. Once appointed as the principal contractor, they become responsible for the health and safety of every contractor involved in the project.

That's a big responsibility. So the person or business appointed as the principal contractor must have the right knowledge, skills and competence under CDM to do the role.

Now we have our facts, let's look at some common myths you might hear about the principal contractor role, that are not necessarily true.

1. Principal contractors are only required on notifiable projects

❌ MYTH

This myth exists because it used to be true. Under the 2007 version of CDM, the principal contractor role was only required on notifiable projects.

However, since 2015, the principal contractor role is required on all construction projects with more than one contractor.

2. The principal contractor is not required on residential projects

❌ MYTH

This is another myth caused by the 2007 version of the CDM regulations. Under the 2007 version, domestic projects didn't trigger a notification, which in turn didn't trigger the requirement for a principal contractor.

However, since 2015, while some duties don't apply to domestic clients, CDM applies to all construction projects, including residential and domestic projects.

3. The principal contractor is the same as the main contractor

❌ MYTH

A main contractor is usually a contractor that takes on a project but may appoint other subcontractors to do the work. They might sometimes be referred to as a general contractor.

Because construction projects can be so varied, it's unusual, especially on larger projects, for one contractor to have all the specialist skills required for every aspect of the work.

scaffold installation

For example, it wouldn't make sense to employ and train employees for scaffold installation when you only need the scaffold put up at the start of the project, and taken down at the end. On a 12-week project, you could have your scaffold team sitting around for 10 weeks.

So a main contractor will often subcontract to other contractors for certain trades.

The principal contractor is a role required under CDM and is the contractor responsible for the construction phase. And if you have a main contractor, since they are in overall control of the construction phase, it makes sense that they will be appointed as the principal contractor.

In that case, the principal contractor and the main contractor will be the same contractor.

But not every construction project has a main contractor.

And if a construction project doesn't have a main contractor, but has multiple contractors, it still needs to have a principal contractor.

For example, on a painting and decorating project, the painter could be the principal contractor.

A main contractor is a type of contractor. A principal contractor is a legal appointment that can be given to any type of contractor - providing they have the skills and competence to do it.


Are you a principal contractor? For help carrying out the role of principal contractor, use the free CDM principal contractor guide.

share on twitter share on facebook share on linked in share by email

This article was written by Emma at HASpod. Emma has over 10 years experience in health and safety and BSc (Hons) Construction Management. She is NEBOSH qualified and Tech IOSH.

Need CDM Help?

Get CDM support on your construction projects with our free guides and support packs for all duty holders.

CDM Support

Recent posts like this...

CDM Notifiable Projects Working Days And Person Days Explained image

CDM Notifiable Projects Working Days And Person Days Explained

Notifiable CDM projects are construction projects that you need to tell the HSE about. If your construction project meets certain criteria - based on project length and the number of people on site - you have to notify the HSE, and your project is notifiable.

Read Post
CDM 2015 Roles And Responsibilities image

CDM 2015 Roles And Responsibilities

The roles of client, principal designer, principal contractor, designers and contractors all have responsibilities under CDM. And so do workers. In this blog post, we will look at what these roles are, when they apply, and what you need to do.

Read Post
What Is Pre-Construction Information? image

What Is Pre-Construction Information?

Pre-construction information is one of the first health and safety documents you will need on a construction project. This is a legally required document, required by the CDM regulations for every construction project.

Read Post

Spend less time on paperwork.
Start with the free plan today.