CDM 2015: When Does It Actually Apply? Domestic, Commercial and One-Day Jobs

Let's get straight to it: when does the Construction (Design and Management) Regulations 2015 (CDM 2015) actually apply? The short answer, and the one too many in the industry still misunderstand, is that it applies to all construction work in the UK.

Yes, you read that correctly. From the smallest one-day job carried out by a single tradesperson to the largest multi-year infrastructure project, CDM 2015 is relevant. The key difference lies in *how* its requirements apply, not *if* they apply. This isn't just bureaucratic red tape; it's the bedrock of sensible risk management on site, aiming to reduce the fatalities and injuries that sadly remain a persistent feature of our industry. The document principal contractors will ask for to evidence that planning is a RAMS — see what a RAMS document is and how to write one.

CDM 2015 Applies to ALL Construction Work – No Exceptions

This is critical. Health and safety law, particularly the overarching Health and Safety at Work etc. Act 1974 (HASAWA 1974) and the Management of Health and Safety at Work Regulations 1999 (MHSWR 1999), underpins CDM 2015. HASAWA requires employers to ensure, so far as is reasonably practicable, the health, safety, and welfare of their employees and to conduct their undertaking in such a way that persons not in their employment are not exposed to risks. MHSWR mandates suitable and sufficient risk assessments.

CDM 2015 then builds on this, providing specific duties for managing health and safety risks within the construction context. Crucially, the regulations define 'construction work' incredibly broadly, encompassing everything from site clearance, preparation, and excavation to building, decorating, demolition, and even the installation of services. If you're undertaking any of these activities, CDM 2015 is in play.

Domestic vs. Commercial Clients: Duties and Differences

Here's where the nuances begin. CDM 2015 clearly distinguishes between commercial and domestic clients.

A commercial client is anyone for whom construction work is carried out as part of their business, or who is a client of a business (e.g., a landlord undertaking work on a rental property). Commercial clients have significant duties under CDM 2015, including:

A domestic client is someone for whom construction work is carried out on their own home, or the home of a family member, that is not in connection with a business. While domestic clients still have ultimate duties under HASAWA, the majority of their specific CDM 2015 client duties are passed on by default to other dutyholders:

The project still has to be safe, of course, and the principal contractor (or contractor) will need to factor in health and safety for the domestic client’s own protection.

• Make suitable arrangements for managing the project.
• Appoint a principal designer and principal contractor if there is more than one contractor.
• Provide pre-construction information to designers and contractors.
• Ensure the construction phase plan is drawn up.
• Ensure welfare facilities are provided.

Single Contractor vs. Multiple Contractors: The Role of Principal Dutyholders

This distinction dictates whether principal dutyholders need to be appointed:

In both scenarios, the contractor (or principal contractor) still has duties to plan, manage, and monitor construction work to ensure it is carried out without risks to health and safety (Regulation 15). They must also provide suitable welfare facilities.

The F10 Notification Threshold: An Administrative Trigger, Not a Safety Standard

Many people mistakenly believe that CDM 2015 only applies if a project is notifiable to the HSE. This is fundamentally incorrect. The F10 notification is a specific administrative requirement, not a trigger for the application of the regulations themselves.

A project is notifiable to the HSE via an F10 form if the construction work is expected to last longer than 30 working days *and* involves more than 20 workers simultaneously at any point, OR if it exceeds 500 person-days.

Even if a project doesn't hit these thresholds, all CDM 2015 duties still apply to the relevant dutyholders. The F10 simply tells the HSE that a specific, larger project is underway.

• If there is only one contractor on the project, the client must appoint a contractor. The contractor then takes on all relevant contractor duties and, importantly, the specific client duties from CDM 2015 Regulations 4(1)(b) (make suitable arrangements for managing the project), 4(6) (provide pre-construction information), 4(7) (ensure construction phase plan is drawn up) and 4(8) (ensure welfare facilities are provided).
• If there is more than one contractor (even if they are on site at different times, as long as their work overlaps or is part of the same project), the client must appoint a principal designer and a principal contractor. If they don't, the client automatically becomes the principal designer and principal contractor, taking on those significant additional duties.

Small Builder, One-Day Job: What Duties Really Apply?

Let's address the common scenario of a small builder undertaking a single-day task, like fitting a new door or repairing a fence. Does CDM 2015 apply? Absolutely.

Even on a one-day job, the builder is a contractor under CDM 2015. Their duties include (but are not limited to):

If this one-day job is for a domestic client, the client's duties are passed to the builder (as the sole contractor). If it's for a commercial client, the commercial client retains their duties, but the builder still has all their contractor duties.

CDM 2015 isn't about disproportionate bureaucracy; it's about embedding a structured approach to safety, regardless of scale. The principles of planning, managing, and monitoring risk are just as valid for a short job as they are for a long one. Neglecting these can still lead to serious incidents, regulatory action, and reputational damage.

Frequently asked questions

Does CDM 2015 apply to all construction work?

Yes, CDM 2015 applies to all construction work in the UK, from the smallest repair to the largest infrastructure project. The extent of the duties varies depending on the project's complexity and client type, but the regulations always apply.

What is the key difference between commercial and domestic clients under CDM 2015?

Commercial clients retain full CDM 2015 duties. For domestic clients, most of their client duties are automatically transferred to the principal contractor (or contractor if there's only one).

When do I need to appoint a principal designer and principal contractor?

You must appoint a principal designer and principal contractor when a project involves more than one contractor. If you don't, and there's more than one contractor, the client automatically assumes these roles, with their associated duties.

Does the F10 notification mean CDM 2015 only applies to larger projects?

No, this is a common misconception. The F10 notification threshold (30 days / 20 workers or 500 person-days) is purely an administrative trigger for informing the HSE. CDM 2015 duties apply to all construction projects, regardless of whether they are notifiable or not.

As a small builder doing a quick job, what are my CDM 2015 duties?

Even on a small, one-day job, you are a contractor under CDM 2015. You must still plan, manage, and monitor the work to ensure safety; carry out risk assessments; provide a suitable site induction; and ensure appropriate welfare facilities. If you're the sole contractor for a domestic client, you also take on their client duties.

Summary

In summary, CDM 2015 is not an optional extra for large construction projects; it's a fundamental piece of health and safety legislation that underpins all construction work in the UK. Understanding its universal application, the distinctions between domestic and commercial clients, and the triggers for appointing principal dutyholders and F10 notification is crucial. Ultimately, CDM 2015 is about ensuring proper planning, management, and resourcing of health and safety from project inception to completion, protecting everyone involved, regardless of the size or duration of the job.

Related reading

• CDM 2015 small builder guide
• Why PCs reject RAMS
• Construction safety documents