Summary

CDM 2015 is the legal framework governing health and safety management on UK construction projects. Many small builders assume CDM only applies to major commercial projects — this is wrong. The regulations apply to virtually all construction work, including domestic extensions, loft conversions, kitchen refits, and bathroom installations. What changes with project size is the extent of formal duties and documentation required.

The key thing to understand for domestic work is the duty holder hierarchy: client, principal designer, principal contractor, designer, and contractor. On a domestic job with a single contractor, most of the client's duties transfer to the contractor. On a job with multiple trades, the principal contractor duties require formal coordination.

CDM compliance is not a tick-box exercise — it is about genuinely planning for health and safety, identifying risks, and managing them. A well-run job where hazards are identified and controlled before work starts is CDM compliance in practice. The paperwork is secondary to the substance.

Key Facts

  • CDM 2015: Construction (Design and Management) Regulations 2015 — applies to all construction work in Great Britain
  • Notifiable projects: Project must be notified to HSE via F10 notification if it will last more than 30 working days with more than 20 workers simultaneously present, OR exceed 500 person-days
  • Domestic client: A private individual commissioning work on their own home — CDM 2015 duties of the client transfer automatically to the contractor (or principal contractor for multi-trade jobs)
  • Commercial client: A business or organisation commissioning construction work — full CDM client duties apply
  • Principal Designer: Required on projects with more than one contractor — responsible for pre-construction health and safety coordination; must have design influence (often the architect or lead designer)
  • Principal Contractor: Required on projects with more than one contractor — responsible for health and safety management during construction
  • Single contractor projects: No requirement to formally appoint Principal Designer or Principal Contractor — the single contractor takes on relevant duties
  • Pre-Construction Information (PCI): The client must provide relevant health and safety information to designers and contractors before work starts — domestic client duty transfers to contractor
  • Construction Phase Plan (CPP): Required for all projects — not just notifiable ones; can be brief for small projects
  • Health and Safety File: Required for notifiable projects — compiled by the Principal Designer; handed to the client on completion; held by the building owner for future reference
  • CDM Co-ordinator: No longer exists under CDM 2015 — replaced by Principal Designer role
  • F10 Notification: Online notification to HSE at https://consult.hse.gov.uk/ — required for notifiable projects before construction phase begins

Quick Reference Table

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Project Type CDM Applies? PD Required? PC Required? Notify HSE?
Single trade, small domestic job Yes No No No
Multi-trade domestic job (e.g. extension with electrician, plumber, builder) Yes Yes (if >1 contractor) Yes (if >1 contractor) Only if notifiable threshold
Extension, 2 tradespeople, 8 weeks Yes Yes Yes No (under 500 person-days)
Large extension, 6 months, multiple trades Yes Yes Yes Likely yes
Commercial refurbishment, any size Yes Yes (if >1 contractor) Yes (if >1 contractor) If notifiable
HMO conversion, 3 contractors, 10 weeks Yes Yes Yes Check calculation
Notifiability Threshold Value
Working days exceeding 30 days with 20+ workers simultaneously
Person-days threshold 500 person-days total
Whichever occurs first triggers notification

Person-day calculation example: 4 workers × 10 days = 40 person-days. 10 workers × 60 days = 600 person-days — this project would need HSE notification.

Detailed Guidance

Does CDM Apply to Domestic Jobs?

Yes. CDM 2015 applies to ALL construction work — domestic or commercial, large or small. However, the specific duties that apply depend on the project type:

Domestic client projects (single homeowner):

  • The client is a domestic client — their CDM duties transfer automatically to the principal contractor (or, if only one contractor, to that contractor)
  • The contractor must still produce a Construction Phase Plan, carry out pre-construction planning, and manage health and safety on site
  • The client must provide any pre-construction information they hold (asbestos surveys, structural information)

Key point: Even a kitchen refurbishment by a single tradesperson must have basic health and safety planning — identification of asbestos, manual handling risk assessment, COSHH for dust and chemicals, work at height assessment if applicable. This is CDM compliance for a small job.

Roles and Responsibilities

Client (domestic or commercial):

  • Appoint a Principal Designer and Principal Contractor where more than one contractor is involved
  • Provide pre-construction information (asbestos surveys, structural information, services locations)
  • Ensure adequate welfare facilities are provided
  • Domestic clients: most of these duties transfer to the contractor

Principal Designer:

  • Responsible for health and safety during the pre-construction phase
  • Ensures designers consider health and safety during design (eliminating hazards through design)
  • Coordinates health and safety information between all designers and the principal contractor
  • Compiles the Health and Safety File
  • Must be an organisation or individual with design influence and skills/experience in health and safety

Principal Contractor:

  • Responsible for health and safety management during the construction phase
  • Prepares and maintains the Construction Phase Plan
  • Ensures all contractors on site understand and comply with health and safety requirements
  • Coordinates all contractors' activities
  • Must have skills, experience, and capability appropriate to the project

Contractors (all trades on site):

  • Co-operate with the Principal Contractor
  • Provide information for the Construction Phase Plan as required
  • Follow the health and safety measures in the plan
  • Ensure their workers are trained and informed

Construction Phase Plan

A Construction Phase Plan (CPP) is required for ALL construction projects — including small domestic work. For a simple single-trade domestic job, the CPP can be brief:

  • Description of the work
  • Identification of significant hazards (asbestos, structural instability, working at height, services)
  • How hazards will be managed
  • Emergency procedures
  • Welfare arrangements

For a multi-trade project or notifiable project, the CPP must be more detailed and should be prepared before work starts.

What a CPP should cover (minimum for domestic projects):

  1. Project description and timeline
  2. Asbestos management — has asbestos been surveyed? What materials might contain asbestos? (See asbestos)
  3. Existing services — gas, electricity, water routes identified and marked
  4. Working at height — how will roof, scaffold, and ladder access be managed?
  5. Manual handling — any heavy lifts requiring mechanical aids or additional manpower?
  6. COSHH — dust control plan, chemical storage, PPE requirements
  7. Site rules — welfare facilities, access control, emergency contacts

Pre-Construction Information

Before starting a domestic project, the contractor should gather:

  • Asbestos information: Has an asbestos survey been done? For properties built before 2000, asbestos may be present — management surveys before disturbance
  • Structural information: Location of loadbearing walls, existing structural alterations
  • Services information: Gas, electricity, water routes — use a cable and pipe detector; request drawings from utility companies if available
  • Neighbour information: Party walls, shared drainage, boundary disputes
  • Environmental information: Is the site on contaminated land? Near a watercourse?

For domestic clients, much of this information may not exist — the contractor should make reasonable efforts to gather what is available and document what cannot be obtained.

HSE Notification (F10)

Notifiable projects must be notified to HSE before the construction phase begins using the F10 online form. The notification includes:

  • Project description and location
  • Client details
  • Principal Designer details
  • Principal Contractor details
  • Project start and end dates
  • Number of workers
  • Number of contractors

Notification is a legal requirement under CDM 2015. The notice must be displayed on site.

Frequently Asked Questions

I'm a sole trader working on a domestic extension — do I need a CDM Construction Phase Plan?

Yes — CDM 2015 applies to all construction work. As a sole trader on a domestic job, you act as both contractor and principal contractor. Your CPP can be simple — a document covering hazards, how you will manage them, and emergency contact information. The key is demonstrating you have thought about health and safety before starting work. Many professional bodies provide simple CPP templates.

What is the difference between a Principal Designer and the architect?

The Principal Designer role is often filled by the architect on projects where the architect has design influence. However, the Principal Designer is a CDM 2015 duty holder with specific health and safety responsibilities — it is not an automatic part of an architect's appointment. The client must specifically appoint the Principal Designer in writing. On projects without an architect (e.g. a builder-led extension), the builder or a specialist CDM advisor may act as Principal Designer.

Do I need to notify HSE for a 6-week kitchen extension?

Calculate the person-days: say 2 workers × 30 working days = 60 person-days. That is well below the 500 person-day threshold. Unless more than 20 workers will be on site simultaneously for more than 30 days (extremely unlikely for a domestic kitchen extension), notification is not required. However, CDM duties still apply — Construction Phase Plan required.

What happens if I don't comply with CDM?

CDM 2015 is enforced by the HSE. Contraventions can result in improvement notices, prohibition notices (stopping work), or prosecution. The penalties for serious CDM breaches include unlimited fines and imprisonment. More commonly, CDM non-compliance is discovered in post-accident investigations — and can significantly affect insurance claims and civil liability if a worker is injured on a poorly-planned site.

Who pays for the Principal Designer on a domestic project?

The client pays — but on a domestic project, the duties transfer to the contractor. In practice, many contractors on smaller domestic projects either act as Principal Designer themselves (if they have appropriate competence) or appoint a CDM consultant for larger or more complex projects. The cost is modest for smaller projects and should be built into the project fee.

Regulations & Standards

  • Construction (Design and Management) Regulations 2015 (SI 2015/51) — primary CDM legislation

  • Health and Safety at Work etc. Act 1974 — underpinning H&S legislation

  • Management of Health and Safety at Work Regulations 1999 — risk assessment requirements

  • L153 — Managing Health and Safety in Construction — HSE's Approved Code of Practice for CDM 2015

  • HSE — CDM 2015 Guidance — Official HSE guidance on CDM 2015

  • CITB — CDM 2015 Guidance for Small Builders — Practical guidance for small contractors

  • HSE F10 Notification Form — Online notification for notifiable projects

  • asbestos — Asbestos identification and management — key CDM pre-construction information

  • working at height — Working at height — major CDM hazard

  • manual handling — Manual handling risk assessment

  • dust control — COSHH dust control plan