There's a version of CDM compliance that exists on paper — a folder somewhere with a Construction Phase Plan that hasn't been touched since the pre-start meeting. Then there's the version HSE expects to find when they walk onto your site. The gap between the two is where most enforcement action originates.
CDM 2015 — the Construction (Design and Management) Regulations — applies to virtually all UK construction work. That covers everything from a commercial fit-out to a groundworks project that runs for a few months. The common misconception is that it only matters once a project becomes notifiable. In reality, the core duties apply from the moment you start planning construction work.
When does a project become notifiable?
A project must be notified to the HSE (via an F10 submission on their online portal) if it's likely to last longer than 30 working days with more than 20 workers simultaneously on site, or exceed 500 person-days total. These are separate thresholds — either one triggers the notification requirement.
The person-days figure catches out projects that don't look large at face value. A 10-person team working for eight weeks clears 400 person-days on its own. Add a brief peak with a few extra trades and you're notifiable before you've really thought about it.
Notification itself is straightforward — you fill in the HSE's online form, get a reference number, and display it on the site notice board. What's less straightforward is everything that flows from it.
What the principal contractor role actually requires
On a notifiable project, someone must be appointed as principal contractor and someone as principal designer. Both appointments should be in writing, made by the client, and made before the construction phase begins. These aren't formalities — they define who is legally responsible for specific duties.
As principal contractor, your duties under CDM Regulation 12 include preparing and reviewing a Construction Phase Plan, organising cooperation between contractors, making sure the site is run safely, and providing workers with relevant site-specific information before they start work. That last one tends to get reduced to "do an induction" — but induction records (who attended, what was covered, signatures) need to be kept for the duration of the project and be available to inspectors.
The Construction Phase Plan itself needs to be more than a template you've reused from another site. HSE guidance (L153) is clear that it should reflect the specific hazards of the project — groundwork near live services, working at height on a particular structure, proximity to the public. Generic plans are a red flag for inspectors because they suggest the principal contractor hasn't really engaged with site-specific risk.
Where companies typically fall short
The most common CDM failures seen during HSE inspections cluster around a few areas:
The CPP isn't updated as the project progresses. CDM Regulation 12(2) requires the plan to be reviewed and updated as the project evolves. If your construction phase plan hasn't been touched since week one and you're now in the structural phase, it's not compliant. It's a document that should grow with the project.
No records of pre-start information being passed to contractors. Under Regulation 4, the client has a duty to ensure pre-construction information is provided. As principal contractor, you need to pass relevant parts of this to the contractors working under you — and you need to show you've done it. An email thread usually suffices, but it has to exist.
Subcontractor RAMS collected once, never reviewed. Risk assessments and method statements from subcontractors need to be specific to the work being done on your site. If a piling contractor submits a RAMS that references a different project, or methods that don't match what you've actually briefed them on, that's a problem. The HSE will want to see that you reviewed them, not just filed them.
No evidence of cooperation between contractors. Site meetings, briefings, and toolbox talks need a paper trail — who attended, what was discussed, anything raised. Without that evidence, you can't demonstrate that you've fulfilled the coordination duty.
The welfare facilities question
Welfare provision — clean toilets, a place to eat, somewhere to dry wet clothing, drinking water — is something inspectors check on every visit. Schedule 2 of CDM sets out what's required based on the scale of the project. It sounds basic, but the number of sites that fall foul of this is significant, particularly on smaller projects where the principal contractor assumes welfare is someone else's problem. It isn't. It's yours.
Daily logs and inspection records
CDM doesn't explicitly mandate a daily site diary, but trying to demonstrate continuous management of a site without one is extremely difficult. A daily record of who was on site, what work was carried out, any issues raised and what was done about them — this is what turns a static CPP into live evidence that the site is being managed. Toolbox talk attendance sheets, completed checklists, incident records — all of this accumulates into the picture of a well-managed project.
In practice, the question isn't whether to keep records, it's how. Paper logs go missing, signatures are illegible, photos end up on someone's phone rather than in a file. That makes compilation for an audit or client review a multi-day job that pulls people away from the actual work.
What this looks like in practice
SiteProof is built specifically around CDM evidence. Daily logs are recorded digitally on site, checklists are completed against CDM-specific templates, incidents are reported with the RIDDOR decision wizard built in, and all of it feeds into a compliance score for each site. When an inspector or client asks for your evidence pack, you're not scrambling to find paperwork — you select a date range and generate a PDF in 30 seconds.
That's not a sales line. It's just the difference between managing compliance in real time and trying to reconstruct it after the fact.
The bottom line
CDM 2015 is not complicated, but it does require consistent effort across the life of a project. The companies that manage it well don't treat it as a box-ticking exercise — they maintain the documentation as the site progresses and keep it available. That's what HSE expects to find, and it's what protects you when things go wrong.
If you're reviewing your CDM processes and want to see how software can take the administrative burden out of the equation, SiteProof offers a 14-day free trial — no credit card required.