CDM 2015 for Domestic Projects: Client, Principal Designer and Contractor Duties

Quick Answer: CDM 2015 (Construction Design and Management Regulations 2015) applies to ALL construction work in Great Britain including domestic projects, regardless of size. For domestic clients, the contractor (or Principal Contractor on multi-contractor jobs) takes on the client duties by default unless a written agreement transfers them. Jobs lasting >30 working days with >20 workers at any point, OR >500 person-days, must be notified to HSE on Form F10. Most domestic extensions and refurbishments are NOT notifiable, but ALL fall under CDM duty.

Summary

CDM 2015 replaced CDM 2007 on 6 April 2015 and brought domestic construction work fully under the regulations for the first time. The major change for residential trades: there is no longer an exemption for "domestic clients" — clients having work done on their own home now sit within the framework, but with their duties automatically transferring to the contractor (single-contractor jobs) or to the Principal Contractor (multi-contractor jobs). Most builders are unaware of this transfer, which means a typical extension contractor is the "client" in the CDM sense for the duration of the work.

This article is for the small builder, sole trader, or general contractor working on residential extensions, refurbishments, conversions and small new builds. It explains how CDM 2015 applies to domestic work, what the contractor's duties actually are, when a job becomes notifiable, and what paperwork must be kept. The practical guidance is for HSE compliance — not legal advice.

For wider compliance see party wall notice templates. For specific dangerous activities see asbestos sampling and working at height (if available).

Key Facts

Quick Reference Table

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Project type Notifiable? PC needed? PD needed? CPP needed?
Single-trade work, 1 person, 2 days No No No Yes (simple)
1-contractor extension, 8 weeks No (unless thresholds met) No No Yes
2-contractor extension, 8 weeks No (unless thresholds met) Yes Yes Yes
Multi-contractor refurb, 4 months Likely (>30 days + 20 workers possible) Yes Yes Yes + F10
Loft conversion, 2 trades, 6 weeks No Yes Yes Yes
Major basement extension, 5 months Yes (likely meets thresholds) Yes Yes Yes + F10
New-build dwelling, 8 months Yes (almost certain) Yes Yes Yes + F10

The notifiable threshold is "30 working days AND 20+ workers at any point" OR "500+ person-days". Most domestic extensions don't meet either threshold.

Detailed Guidance

Who does what under CDM 2015

The regulations identify five duty-holders:

  1. Client — the person who commissions the work
  2. Principal Designer (PD) — designer in control of pre-construction phase (designs, drawings, decisions); only required when more than one contractor
  3. Designer — anyone preparing or modifying a design (architect, engineer, possibly contractor on D&B)
  4. Principal Contractor (PC) — contractor in control of construction phase; only required when more than one contractor
  5. Contractor — anyone carrying out construction work

For a single-contractor domestic project, there is no PD or PC. The single contractor takes on the duties of all roles. The domestic client's duties pass to the contractor.

For a multi-contractor domestic project (e.g. builder + roofer + electrician working separately under client's direction), the regulations require a PD and PC. If the client has not appointed them, the duties pass to the contractor or to the designer — and most often the main contractor on site becomes the de facto PC.

The domestic client transfer — the key thing builders miss

Regulation 7 of CDM 2015 says:

In practice this means: if you're a builder doing a kitchen extension for a homeowner, you are the client in CDM terms unless you've signed a written agreement saying the homeowner takes on the client duties.

Most contractors don't realise this and have never signed an agreement either way. The HSE position: contractor is the duty-holder until written evidence proves otherwise.

What does this mean practically?

Pre-construction information

Before site work starts, certain information must be available:

This information is the basis of the Construction Phase Plan. On a small domestic job, the contractor's site survey notes plus any asbestos survey IS the pre-construction information — keep it on file.

Construction Phase Plan (CPP)

A CPP is required for ALL CDM jobs (the size and detail vary):

For small / single-contractor domestic jobs:

A 1-2 page document covering:

This is not a 30-page formal document. A2-format poster or 2-page A4 typed brief is plenty.

For larger / multi-contractor jobs:

Full Construction Phase Plan to HSE format, drawings, risk register, method statements per activity, COSHH register, programme.

Notification — when and how

A job is notifiable if EITHER:

For typical domestic extensions: 30 working days is easily exceeded (12-20 weeks). But "20 workers simultaneously" is rare on a domestic job — most domestic sites have 3-8 trades coming and going, not 20 at once. So the first threshold rarely triggers.

500 person-days is the more common trigger. Example: a 4-month extension with average 4 workers daily = 80 working days × 4 = 320 person-days. Not notifiable. A 6-month new build with average 6 workers daily = 130 × 6 = 780 person-days. Notifiable.

Notification is via the HSE online portal — Form F10. Submitted BEFORE construction phase starts. Free.

Welfare — non-negotiable from day 1

CDM 2015 Schedule 2 requires welfare facilities from day one:

For a typical domestic extension where the client's home is occupied:

Skipping welfare on a small job is a common breach. HSE inspectors checking a site without welfare = improvement notice or prohibition notice possible.

PPE — last line of defence

Personal Protective Equipment at Work Regulations 2022 require PPE provided where risk control needs it:

PPE is the last line of defence — control hazards at source first (enclosure, extraction, design). PPE provided free of charge to workers.

Specific high-risk activities

CDM identifies certain activities as particularly high-risk requiring specific planning:

Each has its own regulation and assessment process. CDM is the umbrella.

Health and Safety File (HSF)

For multi-contractor projects (where there's a PD), a Health and Safety File is required at the end of the work. Contents:

The PD compiles and passes to the client at end of project. For single-contractor jobs there is no formal HSF requirement but providing equivalent information is good practice and good customer service.

Practical contractor checklist

For a typical domestic extension or refurbishment, here's the practical minimum:

Before quoting:
☐ Site visit and pre-construction risk assessment
☐ Identify any asbestos risk (pre-2000 property)
☐ Identify any structural risk (subsidence, undermined party walls)
☐ Identify any service risks (gas mains, water mains, drainage)

Before starting work:
☐ Written agreement with client on CDM duty transfer (best practice)
☐ Construction Phase Plan drafted
☐ F10 notification if notifiable
☐ Welfare provision arranged
☐ First aider identified
☐ Fire plan and extinguisher provision
☐ PPE supply for own workers

During work:
☐ CPP reviewed if scope changes
☐ Risk assessment updated for new activities
☐ Incident book / accident reporting
☐ Toolbox talks for high-risk tasks

End of project:
☐ Health and Safety File (multi-contractor) or equivalent info pack (single-contractor)
☐ As-built drawings and commissioning records
☐ Customer handover document

Costs of compliance

CDM 2015 compliance for a typical small contractor:

Per project, CDM admin time: 2-6 hours for a typical small extension.

Penalties

HSE enforcement options:

In 2022-2024 HSE has prosecuted multiple domestic project cases. CDM compliance is not optional and is being enforced.

Frequently Asked Questions

Does CDM apply to a single tradesperson on a one-day job?

Yes — CDM applies to all construction work regardless of size or duration. The duties scale with the project, but compliance applies.

My client is a homeowner — do I still need a CPP?

Yes. Domestic client status doesn't remove the CPP requirement; it transfers the client duties to you. CPP is still required.

Can the client be the PC?

Theoretically yes (client appoints themselves as PC). In practice, unrealistic for a domestic project. The contractor takes the duty.

What if I have one subbie on site for one day?

Technically you have more than one contractor — PC and PD duties trigger. In practice for a brief overlap HSE doesn't enforce strictly, but the principle stands.

What's the difference between CDM 2015 and CDM 2007?

CDM 2007 had a "domestic client" exemption — domestic clients had no duties and contractors didn't need to notify HSE for domestic projects. CDM 2015 removed this exemption, brought domestic work fully in, and added the "transfer of client duties to contractor" mechanism.

Is a porch CDM-applicable?

Yes — even a porch falls under CDM. CPP required, even if 1-2 pages. The transfer of client duties still applies.

What if I work with my labourer only — is that "single contractor"?

If your labourer is your direct employee, yes single contractor. If your labourer is a separately-engaged self-employed person (sub-contractor), arguably two contractors — PC and PD duties trigger. The line is fuzzy; safer to plan for multi-contractor framework on any job above the smallest.

Do CIS deductions interact with CDM?

No — CIS is HMRC (Construction Industry Scheme for tax), CDM is HSE (health and safety). Different regulations, different forms, different enforcement.

What about CITB levy?

Construction Industry Training Board (CITB) levy is on businesses doing construction work over a threshold. Not directly CDM but related.

Where can I get a CPP template?

HSE publishes CDM guidance. Multiple commercial template providers (NHBC, IOSH, trade body sites). A 1-2 page template suitable for small domestic work is widely available free.

What if I'm not based in GB?

CDM 2015 applies to construction in Great Britain. Northern Ireland has its own regulations (CDM (Northern Ireland) Regulations 2016 — similar but separate).

Regulations & Standards