When Do the CDM Regulations Apply?
If you are trying to work out when the CDM Regulations apply to your job, the honest answer is simpler and broader than most people expect: they apply to every construction project in Great Britain, whatever its size, cost or duration. There is no minimum threshold below which CDM switches off. This guide sets out plainly when CDM 2015 applies, which duties are triggered by what, and where the common myths, such as the idea that CDM only bites on big or notifiable jobs, come from.
The short answer: CDM applies to all construction work
The Construction (Design and Management) Regulations 2015 apply to all construction work carried out in Great Britain. That includes new build, demolition, alteration, conversion, fit-out, maintenance, repair, redecoration and the installation or removal of services, whether the client is a business or a private householder. A one-day repair is covered just as a two-year new build is covered. What changes with the size and type of project is not whether CDM applies, but which specific duties are triggered and how much paperwork is proportionate.
When each duty is triggered
CDM applies from the very start of every project, but individual requirements kick in at different points. Knowing the triggers helps you see that CDM is always on, even when the heavier duties are not.
- Always, on every project. There is a client with duties, work must be planned, managed and monitored, risks must be controlled proportionately, and workers must have the right information, instruction, training and welfare. None of this depends on size.
- When there is more than one contractor. As soon as a project involves, or is likely to involve, more than one contractor, the client must appoint a principal designer and a principal contractor in writing, and a construction phase plan must be prepared before work starts.
- When the project is notifiable. A project is notifiable, and must be notified to HSE on form F10, if construction work lasts longer than 30 working days and has more than 20 workers working simultaneously at any point, or exceeds 500 person-days. Notification is an extra step; it does not switch CDM on, because CDM was already applying.
CDM applies even to single-contractor and domestic jobs
Two situations trip people up most. The first is the single-contractor job: even when only one contractor is on site, CDM still applies, the contractor must plan and manage the work safely, and a construction phase plan is still required for any construction work, though it can be brief and proportionate. The second is domestic clients, meaning householders having work done on their own home. CDM still applies to that work, but the client duties are normally passed to the contractor, or to the principal contractor where there is more than one contractor, so the householder does not carry them personally. In both cases the regulations are in force from day one.
Where the myths come from
The belief that CDM only applies to large or notifiable projects is a hangover from older regimes and from the notification threshold being the most visible number in the rules. Under CDM 2007 some duties were tied more closely to notifiable projects, and people carried that mental model forward. Others assume that because HSE notification only applies above a threshold, the whole regime must only apply above it. Neither is right under CDM 2015. Notification is one duty among many, and it sits on top of a framework that already applies to every job.
How to apply this on your own project
Start from the assumption that CDM applies, because it does, then scale the duties to the work. For a small single-contractor job, that means a short construction phase plan, sensible risk control and proper welfare. For a project with several trades, add the written appointments of a principal designer and principal contractor and a fuller construction phase plan, and check whether it is notifiable so you can submit an F10 in time. Keeping the paperwork proportionate is the whole point of CDM; the duties flex with the risk, but the regulations themselves never switch off.
Frequently asked questions
Do the CDM Regulations apply to small jobs?
Yes. CDM 2015 applies to all construction work in Great Britain regardless of size, cost or duration, so a one-day repair is covered just as a large new build is. What differs on a small job is that the duties are lighter and the paperwork, such as the construction phase plan, can be brief and proportionate, not that CDM stops applying.
When does a project become notifiable under CDM?
A project is notifiable to HSE on form F10 if the construction work lasts longer than 30 working days and has more than 20 workers working at the same time at any point, or if it exceeds 500 person-days. Notification is an additional duty on larger or longer projects; it does not determine whether CDM applies, because CDM already applies to every project.
Do the CDM Regulations apply to domestic clients?
Yes, CDM applies to work done for domestic clients, meaning householders having work on their own home. The householder does not usually carry the client duties personally; those duties normally pass to the contractor, or to the principal contractor where more than one contractor is involved, so the work is still covered by CDM 2015 from the start.
The shortcut
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This article is general guidance for UK construction and is not legal advice. For requirements specific to your work, check the full text of CDM 2015 and current HSE guidance L153, along with your own duty holder obligations.