For developers, owners and businesses commissioning a build
CDM Regulations 2015: What Clients Must Do
Sviatoslav JerdetchiiCEO & Founder of Craftex. Updated , 5 min read
The short answer
The CDM Regulations 2015 set the health and safety duties on every construction project in Great Britain. The client carries legal duties from the start, and on most projects must appoint a principal designer and a principal contractor in writing.
- Five duty holders: client, designers, principal designer, contractors and principal contractor.
- With more than one contractor, both principal roles must be appointed before the construction phase begins.
- A project over 30 working days with more than 20 workers at once, or over 500 person-days, is notified to HSE on an F10.
- On a home, the client's duties pass to the contractor, the principal contractor or, by written agreement, the principal designer.
The CDM Regulations 2015 decide who is responsible for health and safety on a construction project, from the first drawing to handover. They apply to every project in Great Britain, large or small, commercial or domestic. And the client carries duties from day one.
The Construction (Design and Management) Regulations 2015 came into force on 6 April 2015. They name five duty holders, set what each must do and say when HSE must be told.
This guide is for owners, developers and businesses commissioning a build. We work as a design and build contractor and take the principal contractor role on our projects. Starting a project now? Book a site visit and we will show you how the roles would be set up.
Duty holders under the CDM Regulations
CDM 2015 gives duties to five parties. The client sets the project up. Designers shape the risks on paper. Contractors control them on site. The two principals coordinate each phase when more than one contractor is involved.
| Duty holder | Who it is | Main duties |
|---|---|---|
| Client | Anyone for whom a project is carried out | Arrangements, time and resources; pre-construction information; appointments; checking the principals |
| Designer | Anyone who prepares or modifies a design | Eliminate, reduce or control foreseeable risks in the design |
| Principal designer | The designer appointed to control the pre-construction phase | Plan, manage and monitor that phase; the health and safety file |
| Contractor | Anyone who carries out, manages or controls construction work | Plan, manage and monitor their own work; follow the plan |
| Principal contractor | The contractor appointed to control the construction phase | Construction phase plan, site rules, induction, security, welfare |
Every duty holder must also be competent. Regulation 8 asks for the skills, knowledge and experience for the role, and the organisational capability if it is a firm. Whoever appoints them must take reasonable steps to check.
Client duties under CDM 2015
The client's job is to set the project up so it can be built safely. Get that right at the start and every later duty is easier to meet.
Regulation 4 lists what that means in practice.
- Suitable arrangements. Make arrangements for managing the project, including enough time and other resources, and keep them under review.
- Pre-construction information. Give every designer and contractor the information you hold, as soon as practicable: surveys, asbestos reports, drawings of services and structure.
- The construction phase plan. Make sure one is drawn up before the construction phase begins.
- The health and safety file. Make sure the principal designer prepares it, and keep it available.
- Checking the principals. Take reasonable steps to make sure the principal designer and principal contractor do their duties.
When you sell the building, the file goes to the buyer. Where there is more than one client, one can agree in writing to be treated as the only client.
The principal designer and principal contractor roles
On any project with more than one contractor, the client must appoint a principal designer and a principal contractor in writing. Both are made as soon as practicable, and before the construction phase begins.
The principal designer controls the pre-construction phase. It plans, manages and monitors the design work for health and safety, helps the client assemble pre-construction information and prepares the health and safety file.
The principal contractor controls the construction phase. It draws up the construction phase plan before the site is set up. It organises cooperation between contractors, makes sure everyone gets a site induction, keeps unauthorised people out and provides welfare facilities from the first day.
Our guide to principal contractor vs main contractor covers the difference between the legal role and the contract.
If nobody is appointed
A commercial client that fails to appoint carries the principal contractor's duties itself. That means the plan, the site rules and the welfare, on a site it does not run.
Since 1 October 2023 the Building Regulations have their own principal designer and principal contractor roles, for compliance rather than site safety. One firm can hold both versions of a role, and the client confirms it in writing.
I’m really pleased with my experience working with Craftex. As a commercial construction firm, they handled everything from start to finish without any unnecessary stress on my side. What impressed me was how they suggested practical ideas that improved the design while also keeping things realistic. The communication was always clear, so I never felt out of the loop. The project ran smoothly, deadlines were met, and the end result is exactly what I was hoping for — a space that feels both functional and modern. It’s not easy finding contractors who are this reliable, but Craftex definitely proved they can be trusted.
Notification and the construction phase plan
A project is notifiable to HSE when the work is scheduled to last over 30 working days. It must also have more than 20 workers on site at once at some point. It is also notifiable if it will exceed 500 person-days.
The client sends the notice on HSE's online F10 form, as soon as practicable before the construction phase begins. A copy is displayed in the site office and kept up to date.
Notification is a record, not a trigger. The construction phase plan is needed on every project, notified or not. On a single-contractor job, that contractor writes it.
What a good construction phase plan shows
A useful plan is specific to your building. It names the site rules, the access route and the welfare set-up. It sets measures for higher-risk work such as demolition, work at height or live services. A template with your address pasted in is not a plan.
CDM on domestic projects
CDM 2015 applies to work on homes too. A domestic client is anyone having work done to their own home, or a family member's, outside any business. A whole-house refurbishment of a prime townhouse, a basement dig or a mansard suite is a CDM project like any other.
The difference is who carries the client's duties. Regulation 7 passes them on.
- One contractor. The contractor takes on the client's duties alongside its own.
- More than one contractor. The principal contractor takes them on.
- A written agreement. The client can ask the principal designer, often the architect, to take them on instead.
If a domestic client makes no appointments, the regulations fill the gap. The designer in control of the pre-construction phase is the principal designer. The contractor in control of the construction phase is the principal contractor.
How we handle CDM on our projects
On our projects we take the principal contractor appointment in writing, before the site is set up. Construction is an in-house department and around 60% of the labour is our own. So induction, sequence and the construction phase plan are run by the people doing the work.
For a homeowner, that means the client's duties sit with us as the law intends, not with you. For a developer or a business, one firm holds the contract and the site. The paper trail matches what happens on the ground.
If you are about to start a project in London, book a site visit. We will walk the building with you and set out the CDM roles in writing, with a programme before you commit.
Before work starts
- Pre-construction information handed to every designer and contractor
- Principal designer appointed in writing at the start of design
- Principal contractor appointed in writing before set-up
- Construction phase plan in hand before the construction phase
- F10 submitted if the project is notifiable
- Health and safety file agreed as a handover document
