Compliance Guide

CDM 2015 Guide: A Practical Walk-Through for Every Stage of a Project

A practical guide for UK site managers, contractors and small builders.

Most explanations of the Construction (Design and Management) Regulations 2015 tell you what the rules say. This guide does something more useful: it follows a real project from the first conversation to the final handover and shows you what CDM 2015 actually asks you to do at each stage. If you run sites or take on building work, treat this as a working checklist rather than a legal lecture.

First, the shape of CDM 2015 in one minute

CDM 2015 is the health and safety law for construction work in Great Britain. It applies to every construction project, however small, and it works by giving named roles, called duty holders, specific jobs to do. The five roles that matter on most jobs are the client, the principal designer, the principal contractor, designers and contractors. The bigger and more complex the project, the more formal each duty becomes. On a small single-contractor job the duties still exist, they are just lighter.

The whole system is really about three questions: has the work been planned before it starts, is it being managed while it happens, and has the safety information been passed on at the end. Keep those three questions in mind and the rest of this guide falls into place.

Stage one: before any work starts

This is where CDM 2015 does most of its work, and where most site teams under-invest. Before boots hit the ground, three things need to happen.

The client has to make appointments. Where there is more than one contractor, the client must appoint a principal designer and a principal contractor in writing. If they do not, the client legally takes on those duties themselves, which is rarely what they want. On a single-contractor job the contractor takes the lead role.

Pre-construction information has to be gathered and shared. This is the pack of information about the site and the job that anyone bidding or planning the work needs to do it safely: existing structures, services, ground conditions, asbestos surveys, access constraints and the like. The client provides it and the principal designer pulls it together.

The construction phase plan has to be written before the build begins. This is not optional and it is not a tick-box. It sets out how the specific risks on this job will be controlled. On every project, however small, a construction phase plan must exist before work starts.

Stage two: is the project notifiable?

At this point check whether you need to tell the HSE. A project is notifiable if the construction work is scheduled to either last longer than 30 working days and have more than 20 workers working at the same time at any point, or exceed 500 person days. If either threshold is met, the client is responsible for submitting an F10 notification to the HSE before the construction phase starts, and a copy must be displayed on site. Notifying does not mean the HSE approves anything; it simply tells the regulator the work is happening.

Stage three: during the build

Once work is underway, the principal contractor runs the show on site. The practical CDM tasks during this stage are the ones that keep an inspector happy and, more importantly, keep people safe.

Keep the construction phase plan live. It should reflect what is actually happening, not what you planned three months ago. Update it as the job and its risks change.
Keep risk assessments and method statements current. RAMS should match the task in front of the crew, and the crew should have been briefed on them.
Coordinate the trades. Make sure contractors are cooperating, that changes are communicated, and that one trade is not creating a hazard for the next.
Provide proper welfare. Toilets, washing facilities, drinking water, somewhere to rest and change. This is a hard requirement from day one, not a nice-to-have.
Control site access and induct people. Everyone on site should be inducted and the site should be secured against unauthorised access.

Stage four: at handover

When the job is finished, CDM 2015 has one last requirement where more than one contractor was involved: the health and safety file. This is the record of anything about the completed structure that will be needed to keep future work on it safe, from as-built drawings to details of materials and residual hazards. The principal designer prepares it, or the principal contractor if the principal designer has already left, and it is handed to the client, who must keep it and pass it on if the building is sold.

Scaling it to the size of the job

The commonest worry is that CDM 2015 is too heavy for a small job. It is not, because the duties scale. A domestic kitchen refit with one builder needs a short construction phase plan, sensible RAMS, welfare and a competent contractor. A large multi-contractor commercial build needs formal appointments, an F10, a coordinated plan and a full health and safety file. Same framework, very different weight. The trick is to do what the risk of your job actually requires, and to be able to show it.

The rule in one line: CDM 2015 asks you to plan the work before it starts, manage it while it runs and record it at the end, with the size of the paperwork scaling to the size and risk of the job, so on every project there is a construction phase plan before work begins and, where more than one contractor is involved, a health and safety file at handover.

Frequently asked questions

Does CDM 2015 apply to small jobs?

Yes. CDM 2015 applies to all construction work, including small and domestic projects. The duties are lighter on a small single-contractor job, but there must still be a construction phase plan before work starts, suitable risk assessments, competent workers and proper welfare.

What documents does CDM 2015 actually require?

The three core documents are the pre-construction information, the construction phase plan and, where more than one contractor is involved, the health and safety file. Risk assessments and method statements sit underneath these as the day-to-day evidence that risks are being controlled.

Who is responsible for CDM 2015 on my project?

Responsibility is shared across the duty holders. The client sets the project up and makes the appointments, the principal designer manages safety in the design and pre-construction phase, the principal contractor manages it during the build, and designers and contractors carry out their own specific duties.

The shortcut

Knowing what CDM 2015 wants at each stage is one thing; producing the construction phase plan, RAMS and toolbox talks that prove it is another, and that is the part that eats your evenings. Site Manager AI produces project specific CDM documents in minutes, scoped to current UK regulations, and answers your CDM questions on the spot. You get compliant, professional documents and your evenings back.

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This article is general guidance for UK construction and is not legal advice. For requirements specific to your work, check current HSE guidance, including L153, and your own duty holder obligations under CDM 2015.