CDM 2015 for Small Builders
CDM applies to every construction job, including domestic ones — there is no exemption for being small. The duties just sit differently, and a construction phase plan is required whatever the size.
Plenty of small builders assume the Construction (Design and Management) Regulations 2015 are a big-project thing. They are not. CDM applies to all construction work, including domestic jobs, and the health and safety duties fall on someone regardless of how small the job is.
This guide explains what CDM 2015 actually asks of a small or domestic builder: who holds the duties, the construction phase plan you need on every job, and the narrow circumstances in which you have to notify the HSE.
Key takeaways
- CDM 2015 applies to all construction work, including domestic projects — there is no small-job exemption.
- On domestic projects the client's duties usually pass to the contractor, or the principal contractor.
- If more than one contractor is involved, you need a principal contractor and a principal designer.
- A construction phase plan is required for every project, however small.
- You must notify the HSE (form F10) only on larger or longer projects that pass the thresholds.
CDM applies to you
The most important point is the one most often missed: CDM 2015 covers all construction work, from a full new build down to a domestic extension or a loft conversion. There is no exemption for small jobs. What changes with size is not whether CDM applies, but how the duties are allocated and how much is proportionate.
The regulations are risk-based, so a two-day job carries far less than a six-month site — but the duty to plan, manage and monitor the work for health and safety is there on both.
Who holds the duties on a domestic job
On commercial work the client carries specific duties. On domestic projects — where the client is a homeowner having work done on their own home — those client duties normally pass automatically to the contractor, or to the principal contractor if there is more than one contractor. In practice, on a typical domestic job, the builder ends up carrying them.
That means you are responsible for planning the job safely, managing it, and making sure the people on site are informed and protected. It is not onerous on a small job, but it is your responsibility, not the homeowner's.
On domestic jobs, the duties land on you
Because a homeowner client's CDM duties transfer to the contractor, the small builder usually carries them. Know that going in — assuming 'the homeowner is the client, so it's their problem' is exactly the misunderstanding CDM closes.
Principal contractor and principal designer
Where a project involves more than one contractor — which is most jobs, once you count the electrician, the plumber and the plasterer — the regulations require a principal contractor and a principal designer to be appointed. On a small domestic job, you as the main builder are typically the principal contractor, coordinating the trades and managing the site safely.
The principal designer role covers managing health and safety in the design and planning phase. On simple jobs these roles are light-touch, but they must be filled; leaving them unassigned is a CDM breach even on a small site.
Construction phase plan and notifying the HSE
A construction phase plan is required for every construction project, however small — it does not have to be a thick document, but it must set out the health and safety arrangements for that specific job: the risks, how you control them, and the site rules. For a small job a short, proportionate plan is fine and expected.
Notification to the HSE, on form F10, is a separate and narrower requirement. You only notify where the work is scheduled to last longer than 30 working days with more than 20 workers on site at the same time, or exceeds 500 person-days. Most small domestic jobs fall well under those thresholds and are not notifiable — but they still need the phase plan.
Keep the phase plan with the job
Store your construction phase plan and site records against the job in TradePlanr, so the health and safety paperwork for each project is filed alongside the quote, variations and certificates rather than lost in the van.
Frequently asked questions
Does CDM 2015 apply to domestic jobs?
Yes. CDM applies to all construction work, including domestic projects — there is no small-job exemption. On domestic work the client's duties normally pass to the contractor or principal contractor, so the builder usually carries them.
Do I always need a construction phase plan?
Yes. A construction phase plan is required for every project regardless of size. For a small job it can be short and proportionate, but it must set out the health and safety arrangements for that specific work.
When do I have to notify the HSE?
Only on larger projects: where the work will last more than 30 working days with over 20 workers on site simultaneously, or exceed 500 person-days. Most small domestic jobs are below these thresholds and are not notifiable, but still need a phase plan.
From guidance to action
Related guides
Building Regulations for Extensions
Which Approved Documents apply, building control routes, and sign-off on a domestic extension.
How to Write a Construction Quote
What a solid building quote includes, quote vs estimate, and terms that prevent disputes.
How to Price a Loft Conversion
Costing a loft conversion by type, the trades involved, and invoicing a long job in stages.
