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UK CDM 2015 (Construction Design and Management Regulations 2015)

Statutory health-and-safety duties for every UK construction project under SI 2015/51. Domestic renovations have specific simplified obligations (HSE F10 notification threshold, Principal Designer + Principal Contractor roles). Homeowners are technically the 'client' but duties default to the contractor on domestic work.

Established 2015·Official site →·Verify →

UK CDM 2015 — Definitive Construction Health & Safety Guide 2026

The UK Construction (Design and Management) Regulations 2015 (SI 2015/51) — universally referred to as "CDM 2015" — are the statutory health-and-safety regulations governing every construction project in Great Britain. The regulations are administered by the Health and Safety Executive (HSE) and impose mandatory roles, mandatory documentation, and mandatory health-and-safety planning on every project regardless of scope or duration. Domestic renovations have specific simplified obligations — the homeowner is technically the "client" but the regulations' duties default to the appointed contractor when the homeowner does not actively assume them.

What it governs

CDM 2015 establishes seven duty-holder roles for any construction project:

Each duty-holder has specific statutory duties under Regulations 4 to 17. Documentation includes the Pre-Construction Information (PCI) packet, the Construction Phase Plan (CPP), and (for projects exceeding 30 working days plus 20 workers OR 500 person-days) the F10 notification to HSE.

The domestic-client provision under Regulation 7 is critical: domestic clients (homeowners) are NOT required to actively comply with the duties — those duties default to the Principal Contractor. The PC therefore takes on the homeowner's CDM duties unless the homeowner explicitly assumes them in writing.

Homeowner implications

For a UK homeowner — London, Birmingham, Manchester, Bristol, Leeds — CDM 2015 creates a transparent risk-allocation framework. By default, the homeowner does NOT need to actively manage health-and-safety on the project. The Principal Contractor assumes those duties.

Practical homeowner implications:

The homeowner SHOULD verify that the Principal Contractor has prepared a Construction Phase Plan and has the welfare facilities (toilet, washing, drinking water) on site as required under Schedule 2.

Contractor implications

For a contractor undertaking domestic work, CDM 2015 obligations shift heavily toward the contractor as default Principal Contractor on domestic projects. The Construction Phase Plan must be prepared before work starts, kept on site, and updated as conditions change. Welfare facilities must be provided on site (toilet, washing, drinking water, rest area for breaks).

For multi-contractor projects, formal Principal Designer + Principal Contractor appointments are required. The PD coordinates pre-construction health-and-safety; the PC coordinates construction-phase health-and-safety. The two roles can overlap with the architect/designer + main contractor on small projects.

F10 notification to HSE is required for projects expected to exceed thresholds. Failure to notify is a strict-liability HSE offence. The penalty range is significant — HSE prosecutes under the Health and Safety at Work etc. Act 1974 with unlimited fines on conviction.

Contractor competency is essential — HSE expects every appointed contractor and designer to demonstrate skills, knowledge, and experience appropriate to the work scope. CSCS card schemes, professional-body memberships (CIOB, RIBA, RICS, IStructE), and project portfolios are the standard evidence base.

How AskBaily uses it

Every AskBaily London + UK metro match runs:

Recent changes 2024–2026

The 2024 HSE CDM 2015 supplementary guidance clarified the domestic-client provision and tightened expectations on Construction Phase Plan documentation for small projects. The 2025 Building Safety Act 2022 secondary regulations layered additional duties onto higher-risk buildings (Higher-Risk Buildings as defined in the Act — over 18m or 7+ storeys + at least 2 residential units), with implications for the CDM Principal Designer role on those projects.

The Building Safety Regulator (BSR) is now the AHJ for CDM-related higher-risk-building duties under the BSA 2022 regime; HSE retains all other CDM enforcement.

Frequently asked questions

Does CDM 2015 apply to my home extension? Yes — every construction project in GB falls under CDM. Single-contractor domestic projects have simplified obligations.

What's the F10 notification threshold? Projects expected to exceed 30 working days with 20+ workers OR 500 person-days. Most domestic renovations fall below.

As a homeowner, do I have CDM duties? As a domestic client, your duties default to the Principal Contractor unless you assume them in writing. In practice, you have minimal CDM exposure on a single-contractor project.

What's a Construction Phase Plan? A written document the Principal Contractor prepares before work starts, identifying significant risks and how they will be managed.

Where do I find the regulations? legislation.gov.uk SI 2015/51 and HSE's Managing Health and Safety in Construction.

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