> Disclaimer: SiteKiln gives you plain-English information, not legal or health and safety advice. Always follow your site-specific risk assessments and talk to a qualified professional.
The short version
CDM 2015 says everyone involved in a construction job has clear legal duties: the client, principal designer, principal contractor, other contractors and workers.
On most small jobs, your LTD or sole trader business will be treated as the contractor or principal contractor, and you personally will also count as a worker with your own responsibilities.
Why it matters
If something goes badly wrong, HSE will not accept "we didn't know who was responsible" -- CDM sets it out in black and white. On small sites, roles often blur: the builder "sorts everything", the designer is half-in and half-out, and the client assumes it's all being handled. That's exactly how people end up in court under CDM and the Health and Safety at Work Act.
Knowing which hat you're wearing -- client, principal contractor, contractor, worker -- tells you what paperwork you need and what "good" actually looks like for a job your size.
The main CDM roles in plain English
For most readers, these are the ones that matter:
- Client -- the person or company having the work done (domestic homeowner, landlord, developer, small business owner).
- Principal designer (PD) -- the designer in control of pre-construction phase where there is more than one contractor.
- Principal contractor (PC) -- the main contractor in control of the construction phase where there is more than one contractor.
- Contractor -- anyone who carries out, manages or controls construction work (this includes small builders, gangs, and specialist trades).
- Worker -- the people doing the work on site (includes your own lads/ladies, labour-only, and often you as the owner if you're on the tools).
On most micro jobs:
- The homeowner is the domestic client -- their CDM duties get passed to the contractor or principal contractor by law.
- Your small building firm is the contractor, and often also the principal contractor if you bring in more than one trade.
- If there's an architect or structural engineer leading design, they may be the principal designer; if not, some PD duties land on the PC by default.
Who is responsible for what
Think of this as the "who owns what" map. This is simplified for small and medium projects.
| Role | Typical example on your jobs | Main legal duties in CDM 2015 (cut-down) |
|---|---|---|
| Client | Homeowner, landlord, small business owner having the work done | Make sure arrangements are in place for managing the project, appoint PD/PC in writing, provide information about the site, allow enough time and money. |
| Principal designer | Architect / engineer leading design where there's more than one contractor | Plan, manage and monitor the pre-construction phase, coordinate design work, eliminate or reduce risks through design, pass information to PC and others. |
| Principal contractor | Main builder running the job where there's more than one contractor (often you) | Plan, manage and monitor the construction phase, prepare and implement the Construction Phase Plan, organise site inductions, coordinate trades, consult workers. |
| Contractor | Each trade contractor (including small builder if only contractor) | Plan, manage and monitor their own work, make sure workers are competent and supervised, follow the Construction Phase Plan, produce RAMS where needed. |
| Worker | Anyone on the tools, including you if you're working on site | Take care of own and others' safety, follow site rules and training, use the right PPE and equipment, report hazards and problems. |
For domestic clients, CDM says their duties automatically transfer to the contractor or principal contractor -- so if you're the only contractor, you effectively carry both your own contractor duties and most of the client CDM duties too.
What this means for a small builder in practice
If you're a small LTD or sole trader, CDM 2015 bites in a few key ways.
If you are the only contractor on the job
Example: bathroom refurb, small extension where you don't bring in other firms.
- You are a contractor under CDM.
- On domestic work, most of the client's CDM duties pass to you automatically.
- You must:
- Plan, manage and monitor the work so it's carried out safely (basic risk assessments, method statements, sequencing).
- Make sure workers you use are competent and properly supervised.
- Provide basic welfare (toilets, washing, drinking water, etc.).
- Cooperate with any designer to control risks (e.g. temporary works, structural changes).
- You still need a Construction Phase Plan (CPP), even for small jobs, but it can be short and proportionate.
If you are the principal contractor
Example: you run an extension, bring in a roofer, electrician, plumber, maybe a groundworker.
- You are both principal contractor and a contractor.
- You must:
- Prepare, update and actually use a Construction Phase Plan that covers how you'll manage H&S on the project.
- Organise site inductions, briefings and toolbox talks so everyone knows the risks and rules.
- Coordinate trades so they don't create extra risks for each other (e.g. not having roofers working directly above brickies).
- Check other contractors you bring in have the right skills, experience and systems, not just the cheapest quote.
- Make sure there are sensible site rules -- access, housekeeping, PPE, segregation from the public.
- If there's a principal designer, you need to share information both ways. If there isn't one (common on small domestic jobs), you will often find PD-type tasks pushed onto you in practice anyway.
If you are just one of several contractors on a bigger site
Example: you're a small bricklaying firm working under a national main contractor.
- You are a contractor and your lads are workers under CDM.
- The principal contractor must have a Construction Phase Plan and a site induction -- you must follow it and feed in your own risks.
- You still have to plan, manage and monitor your part of the work, provide RAMS where needed, and make sure your people are competent.
- You must cooperate with the PC and other contractors: attend coordination meetings, follow instructions from the PC/PD on safety, and share risk information.
- CDM doesn't let you say "health and safety is the main contractor's problem" -- you have your own duties either way.
What happens if you get CDM wrong
If there's an incident or inspection and CDM duties haven't been met, HSE can:
- Serve improvement notices -- requiring you to put proper arrangements in place, create a Construction Phase Plan, improve welfare, etc., by a set deadline.
- Serve prohibition notices -- stop part or all of the work immediately if there's a risk of serious personal injury.
- Prosecute dutyholders (client, PC, PD, contractors and in some cases individuals like directors) for serious or repeated breaches -- this can mean large fines and, in the worst cases, prison.
Because CDM is about management and planning, you can be in trouble even if nobody has been hurt yet -- "we've always done it this way" is not a defence.
What to do on your next job
Use this as a quick checklist:
Before you price or start:
- Work out who is the client, principal contractor, principal designer (if any), and what you are under CDM.
- If you're PC or sole contractor, sort a simple Construction Phase Plan and basic risk assessments before you break ground.
If you are the main or only contractor:
- Make sure the client gives you any relevant information (asbestos surveys, existing drawings, known hazards).
- Keep site inductions, briefings and checks proportionate but real -- a 10-minute induction and a simple set of site rules is better than a thick folder nobody reads.
If you are a subcontractor:
- Ask for the Construction Phase Plan and site rules; don't just assume they exist.
- Provide your own RAMS where the work is risky (work at height, lifting, etc.), and actually brief them to your workers.
Personally, as someone on the tools:
- Treat yourself as a worker under CDM -- report hazards, follow the plan, and use your right to refuse clearly unsafe work as covered in 4.1.
What to do next
- Work out which CDM hat you wear on your current job -- client, principal contractor, contractor or worker -- and check you're actually doing what the regs expect for that role.
- Download HSE's free "CDM for small builders" leaflet and keep it in your site folder.
- Write a simple Construction Phase Plan for your next job -- even a one-page version is better than nothing.
- If you're bringing in subbies, make sure you've got their competence on file before they start, not after.
- Brief your team at the next toolbox talk on who is responsible for what under CDM on the current job.
Sources
- Construction (Design and Management) Regulations 2015 -- dutyholder roles and responsibilities.
- Health and Safety at Work etc. Act 1974 -- general duties of employers.
- HSE -- "Are you a small builder?" and small-builder expectations under CDM.
- HSE -- information for people doing or having construction work carried out (including domestic clients).
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