CDM 2015 guide
A plain-English guide to CDM 2015 — what it means, who it applies to, and what you actually need to do as a builder or contractor working in the UK.
CDM stands for the Construction (Design and Management) Regulations 2015. These are the main health and safety regulations for the UK construction industry. They apply to all construction work in Great Britain — from a bathroom refit to a multi-storey office block. There are no exemptions based on project size or value.
CDM 2015 replaced CDM 2007 on 6 April 2015 and brought several changes — most notably extending the regulations to cover domestic projects and simplifying the duty holder structure. The full text is published by the Health and Safety Executive (HSE), along with guidance documents L153 and INDG411.
CDM 2015 applies to every construction project in Great Britain — commercial and domestic. If you are doing construction work of any kind, CDM applies to you. This includes sole traders, self-employed subcontractors, small builders, and large contractors. The regulations cover new builds, extensions, refurbishments, demolition, maintenance, and repair work.
The extent of what you need to do depends on your role and the scale of the project. But the basic principle is the same for everyone: construction work must be planned, managed, and monitored to ensure it is carried out safely.
CDM 2015 defines six duty holder roles. On a small domestic job, one person might fill several roles. On a large commercial project, each role is usually a separate appointment.
The person or organisation the work is being done for. On commercial projects, the client must make suitable arrangements for managing the project, ensure adequate welfare facilities, and appoint a principal designer and principal contractor when there is more than one contractor. The client does not need to manage health and safety directly, but they must make sure someone competent is doing it.
A homeowner or occupier having work done on their own home. Domestic clients have the same duties as commercial clients under CDM 2015, but those duties are automatically passed to the contractor (or principal contractor, if there is more than one). In practice, this means the builder takes on the CDM duties — including producing a Construction Phase Plan.
Anyone who prepares or modifies a design for a building or structure. This includes architects, structural engineers, building services engineers, and interior designers — but also contractors who design temporary works or change a design on site. Designers must eliminate, reduce, or control foreseeable risks through their design choices.
On projects with more than one contractor, the client must appoint a principal designer to plan, manage, monitor, and coordinate the pre-construction phase. The principal designer ensures that designers cooperate and that health and safety risks are addressed in the design. On domestic projects with one contractor, this role is not required.
On projects with more than one contractor, the client must appoint a principal contractor to plan, manage, monitor, and coordinate the construction phase. The principal contractor must produce the Construction Phase Plan, ensure cooperation between contractors, and manage site safety. On domestic projects, these duties transfer to the contractor automatically.
Anyone carrying out construction work, including sole traders, subcontractors, and self-employed tradespeople. Every contractor must plan, manage, and monitor their own work to ensure it is carried out safely. They must cooperate with the principal contractor (if there is one), provide information and training to workers, and not start work unless satisfied that adequate welfare facilities are in place.
Not every project needs to be notified to the HSE. A project is notifiable if it meets either of these thresholds:
If your project is notifiable, you must submit an F10 notification form to the HSE before work begins. The F10 includes basic project details — address, client, principal designer, principal contractor, start date, and expected duration. The Site Book checks notifiability automatically and pre-fills the F10 from your project data.
Even if your project is not notifiable, you still need to comply with all other CDM 2015 requirements — including producing a Construction Phase Plan, carrying out risk assessments, and ensuring adequate welfare facilities.
One of the biggest changes in CDM 2015 was extending the regulations to domestic projects. Under CDM 2007, domestic clients were largely exempt. Now, the same duties apply — but with an important difference in how they are allocated.
On a domestic project (work done on a home that is not connected to a business), the homeowner’s CDM duties are automatically transferred to the contractor. If there is only one contractor, they take on all the client duties. If there are multiple contractors, the duties transfer to the principal contractor — or to whichever contractor the domestic client appoints in writing.
On a commercial project, the client retains their own duties and must actively manage them — including appointing a principal designer and principal contractor when there is more than one contractor on site.
In practice, this means that on most domestic jobs — extensions, loft conversions, kitchen and bathroom refits — the builder is responsible for CDM compliance. This includes producing a Construction Phase Plan, carrying out risk assessments, and ensuring welfare facilities are in place.
If you are a sole trader or small builder working mostly on domestic projects, CDM 2015 means you need to:
The good news is that CDM is proportionate. A domestic extension does not need the same level of documentation as a multi-storey commercial build. A 1-2 page Lightweight CPP and a site-specific RAMS are usually sufficient for a small domestic job. The Site Book is designed specifically for this — creating proportionate, compliant documentation for small builders without the enterprise overhead.
Reality: CDM 2015 applies to ALL construction work in Great Britain — including domestic extensions, loft conversions, bathroom refits, and kitchen installations. There are no exemptions based on project size.
Reality: Every construction project needs a Construction Phase Plan. On domestic projects where you are the sole contractor, the duties transfer to you. The CPP does not need to be a 20-page document — a proportionate plan covering the key risks is sufficient.
Reality: On domestic projects, the homeowner’s CDM duties are automatically transferred to the contractor (or principal contractor if multiple contractors are involved). The homeowner does not need to do anything specific — it is the builder’s responsibility.
Reality: CDM is about planning and managing work safely. The documentation — the CPP, RAMS, and other records — is the evidence that you have done the thinking. But the purpose is to prevent accidents, not to produce paper.
Reality: All projects need CDM compliance. Notifiable projects (those lasting more than 30 working days with more than 20 workers, or exceeding 500 person-days) have the additional requirement of notifying the HSE via an F10 form. But every project — notifiable or not — must comply with CDM 2015.
The Site Book creates professional Construction Phase Plans and RAMS that meet CDM 2015 requirements.
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CDM stands for the Construction (Design and Management) Regulations. The current version is CDM 2015, which came into force on 6 April 2015 and replaced CDM 2007. The regulations set out the duties of everyone involved in a construction project — from the client and designers through to contractors and workers — to ensure that health, safety, and welfare are properly managed throughout the project.
Yes. CDM 2015 applies to all construction work in Great Britain, including work on domestic properties. The key difference is that on domestic projects, the client’s duties are automatically transferred to the contractor (or principal contractor if there are multiple contractors). This means the builder is responsible for producing the Construction Phase Plan, managing site safety, and ensuring adequate welfare facilities — even on a simple kitchen extension or bathroom refit.
An F10 is a notification form that must be sent to the Health and Safety Executive (HSE) before work starts on a notifiable project. A project is notifiable if it will last longer than 30 working days and have more than 20 workers on site at any one time, OR if the project exceeds 500 person-days of construction work. The F10 includes basic project details — address, client, principal designer, principal contractor, start date, duration, and a brief description of the work. You can submit it online through the HSE website.
On a domestic project, the homeowner’s CDM duties are automatically transferred to the contractor. If there is only one contractor on site, they take on all the client’s duties — including producing a Construction Phase Plan and ensuring adequate welfare facilities. If there are multiple contractors, the client’s duties transfer to the principal contractor, or to the contractor appointed in writing by the domestic client. In practice, on most domestic jobs, the main builder takes on all CDM responsibilities.
Your duties under CDM as a sole trader or small builder.
What builders need to know about domestic projects and CDM.
CDM roles explained — principal contractor vs contractor.
When and how to notify the HSE about your project.
Everything you need to know about CPPs.
Risk Assessments and Method Statements explained.
The Site Book creates your CPP, RAMS, and site documentation in minutes. CDM 2015 compliant. Your first project is free.