CDM 2015 compliance guide UK 2026: the complete reference for trades, contractors and clients
CDM 2015 explained in plain English. The duties for clients, principal designers, principal contractors and contractors. Notification thresholds, documentation requirements, and how to actually meet your duties.
The Construction (Design and Management) Regulations 2015 - CDM 2015 - are the legal framework that governs how UK construction projects are planned and managed. They place legal duties on every party involved in a construction project: clients, designers, contractors, and workers. Understanding these duties is not optional - failure to comply carries criminal liability under the Health and Safety at Work etc Act 1974. This guide explains what CDM 2015 requires in plain English, who has to do what, when notification is required, and how trades businesses can meet their duties without the paperwork swallowing the actual work.
What CDM 2015 actually is
CDM 2015 came into force on 6 April 2015, replacing the previous CDM 2007 regulations. The 2015 version simplified the framework, removed the requirement for a CDM coordinator, and added a new duty holder called the Principal Designer. The regulations apply to all UK construction work regardless of size, though the specific duties scale with project complexity.
The core principle is that everyone involved in a construction project has a duty to plan, manage, and monitor work to ensure it is carried out safely. This applies to the smallest extension as much as a major commercial development. The legal duty cannot be delegated by signing it away in a contract - if you have a CDM duty, you have it regardless of what your contract says.
CDM 2015 is enforced by the Health and Safety Executive (HSE). Breaches can result in improvement notices, prohibition notices (which can stop work entirely), and prosecution. Recent years have seen six-figure fines for individual breaches and personal prosecutions of directors and managers.
The five duty holders under CDM 2015
1. Clients
The client is the person or organisation for whom the construction work is being done. They have the most fundamental duties under CDM 2015 because they set the timeframe, budget and project culture that determines whether safety is genuinely prioritised.
Client duties include: making suitable arrangements for managing the project; ensuring adequate time and resources are allocated; appointing competent designers and contractors; ensuring a Principal Designer and Principal Contractor are appointed where required; ensuring a Construction Phase Plan is prepared before work starts; ensuring welfare facilities are provided; and notifying the HSE where required.
In practice, client duties are often poorly understood by domestic clients (people having work done on their own home). HSE guidance recognises this and the duties of domestic clients automatically transfer to the contractor or Principal Contractor in most cases.
2. Principal Designers
A Principal Designer is required for any project with more than one contractor. The Principal Designer plans, manages, monitors and coordinates health and safety in the pre-construction phase. They identify foreseeable risks, prepare the pre-construction information, and produce the Health and Safety File at the end of the project.
The Principal Designer must be appointed in writing by the client. Crucially, the role can be carried out by the architect, engineer or other lead designer who already has design responsibility - it does not have to be a separate party. Many designers refuse Principal Designer appointments because the criminal liability is significant; this can leave clients struggling to find a willing party.
3. Principal Contractors
A Principal Contractor is required for any project with more than one contractor on site. The Principal Contractor plans, manages and monitors construction phase health and safety. They prepare the Construction Phase Plan, liaise with the Principal Designer, ensure all contractors are competent, and run the site safety arrangements.
The Principal Contractor must ensure suitable welfare facilities are in place from day one. They must induct workers, supervise contractor activities, and produce daily site records. On larger projects they typically operate a permit-to-work system, manage hot works, and coordinate emergency procedures.
4. Designers
Anyone whose work involves preparing or modifying designs has duties as a Designer under CDM 2015. This includes architects, engineers, technicians, principal contractors making design changes, and even contractors selecting materials. The duty is to eliminate foreseeable risks where possible and reduce them where elimination is not possible.
Designers must consider the construction phase, the maintenance phase, and the eventual demolition. A common failure is designing roof access points that look fine on paper but require working at height to maintain - the duty is to anticipate this and design it out.
5. Contractors
Contractors are anyone who carries out construction work. This includes the trade businesses that make up most of the UK construction industry - scaffolders, electricians, roofers, plumbers, groundworkers and so on. Contractor duties under CDM 2015 are the most operationally relevant for day-to-day work.
Contractor duties include: planning, managing and monitoring work; cooperating with the Principal Contractor; following the Construction Phase Plan; ensuring workers are competent and trained; providing site induction; complying with welfare requirements; and ensuring suitable plant and equipment is provided and maintained.
Crucially, the contractor must produce a project-specific Risk Assessment and Method Statement (RAMS) for their work activities. This is the operational documentation that demonstrates how the work will be carried out safely. Generic RAMS templates that have not been adapted to the specific project fail this duty.
Notification thresholds: F10 and the HSE
CDM 2015 requires notification to the HSE for projects that meet either of two thresholds. The notification is made on Form F10, which is submitted online via the HSE website. Notification must be made before construction work starts.
The two thresholds are:
- The construction work is scheduled to last longer than 30 working days AND involves more than 20 workers working simultaneously at any point in the project
- The construction work is scheduled to exceed 500 person-days
If either threshold is met, the project is "notifiable" and an F10 must be submitted. The client is responsible for ensuring notification happens - though in practice the Principal Contractor often handles the form on the client's behalf.
A notifiable project does NOT require additional CDM duties beyond those that already apply - it just adds the notification requirement. Many trades mistakenly think notifiable projects are subject to a different (more onerous) regulatory regime; they are not.
Documentation requirements
Pre-construction information (PCI)
The client (or someone appointed by them) must compile pre-construction information that includes everything the design team and contractors will need to know about the project, the site, and any existing hazards. This typically covers asbestos surveys, structural information, services drawings, neighbour information, ground conditions, and any client-specific safety arrangements.
Construction Phase Plan (CPP)
Before work starts, the Principal Contractor (or contractor on a single-contractor project) must prepare a Construction Phase Plan. This document covers how health and safety will be managed during the construction phase: site arrangements, welfare, supervision, induction, emergency procedures, traffic management, and the procedures for managing specific hazards.
The CPP is a living document that gets updated as the project progresses. It is the primary HSE inspection target - inspectors will ask to see the CPP and will check whether site practice matches what the document says.
Health and Safety File
At the end of the project, the Principal Designer prepares a Health and Safety File for the client. This document captures information that will be needed for future maintenance, alteration or demolition - structural details, materials used, services routes, maintenance access, and any unusual hazards. The File becomes part of the building information that gets passed to subsequent occupiers.
RAMS for each work activity
Every contractor needs a Risk Assessment and Method Statement for each work activity. This is the operational document that translates the high-level CPP into the actual safety arrangements for specific work. Most contractors produce one RAMS per significant activity (scaffolding erection, lead works, deep excavation, etc.) rather than a single RAMS for the entire project.
Worker competence under CDM 2015
CDM 2015 requires that everyone involved has the skills, knowledge, training and experience to carry out their duties safely. This is collectively known as "competence". Industry uses the CSCS card scheme as the primary evidence of competence for site workers, but cards alone are not sufficient - the actual skills and experience must back up the card.
Specific competence regimes apply to specific trades:
- Scaffolders: CISRS card scheme
- Electricians: NICEIC, NAPIT, ECS card scheme
- Gas engineers: Gas Safe registration
- Plant operators: CPCS or NPORS cards
- Roofers: NFRC training schemes
- Construction workers generally: CSCS card scheme
The Principal Contractor has a duty to ensure all workers on site have appropriate competence. Most main contractors verify cards and training records before allowing access to site. Documentation of card numbers, expiry dates and training certificates is therefore essential.
How CDM 2015 applies to common scenarios
Single contractor on a domestic property
One contractor working on a homeowner's property: the contractor takes on the client's CDM duties (because domestic clients are exempt). The contractor must produce a Construction Phase Plan, even for small jobs. F10 notification is unlikely to be required because the project will rarely exceed 30 days with 20+ workers. RAMS for the work activities are required.
Multiple contractors on a domestic extension
Multiple contractors (e.g. groundworker, builder, roofer, electrician, plumber) on a domestic extension: a Principal Contractor must be appointed. The Principal Contractor takes responsibility for site coordination. The lead designer typically becomes Principal Designer. CPP, RAMS and induction records all required. Domestic client duties transfer to the Principal Contractor.
Commercial new build, 6-month programme, 30+ workers
Notifiable project: F10 required. Principal Designer and Principal Contractor formally appointed. Pre-construction information compiled by client. Full CPP, weekly site safety meetings, induction logs, daily site records. Health and Safety File compiled at end. Multiple RAMS for each work package.
Subcontractor (your trade) working under a Principal Contractor
You are bound by the Construction Phase Plan. You must follow the Principal Contractor's site rules. You produce your own RAMS for your work activities. You ensure your workers are competent and have appropriate training. You cooperate with other contractors and the Principal Contractor. You report incidents through the Principal Contractor's reporting system.
Common CDM 2015 mistakes
Treating CDM as a paperwork exercise
The most common failure is producing CDM documentation that is technically present but operationally meaningless - a Construction Phase Plan that nobody on site has read, RAMS copied from a previous project without adaptation, induction records that exist but where the induction itself was rushed. HSE inspectors look at site practice as much as paperwork.
Confusion about who is the Principal Contractor
On smaller jobs the Principal Contractor role often gets unclear. If multiple contractors are on site, someone is the Principal Contractor regardless of whether anyone has been formally appointed. The default is whoever has the largest scope of work, but this should be clarified in writing.
Not appointing a Principal Designer
Smaller projects often skip the Principal Designer appointment, but the role is required for any project with more than one contractor. A common workaround is appointing the architect or lead designer as Principal Designer where they would normally have design coordination responsibility anyway.
Generic RAMS
Templates downloaded from the internet, copied between projects, with the project name swapped out. This fails the project-specific requirement and is a frequent cause of contractor rejection on pre-start checks. AI-generated RAMS that are customised to the actual scope (like the Complys RAMS builder) solve this efficiently.
Forgetting domestic client transfer
When working on domestic premises, the contractor often forgets that they have inherited the client duties. This means producing the CPP, ensuring Principal Designer is appointed if multi-contractor, and managing the project safety arrangements - duties most domestic builders are not used to carrying.
How Complys helps with CDM 2015
Complys is built around the operational requirements of CDM 2015 for UK trades businesses. The platform handles:
- Insurance, accreditation and worker training records (the competence side)
- AI-generated trade-specific RAMS in 30 seconds (the project-specific RAMS requirement)
- Construction Phase Plan templates for Principal Contractor projects
- Worker passports with CSCS, ECS, CISRS, Gas Safe and other competence cards tracked
- Pre-start documentation packs that bundle insurance, RAMS, accreditations and worker passports for sharing with main contractors
- Compliance share links so main contractors can verify your CDM-relevant documentation in one place
- Site induction tracking with worker sign-off records
- RIDDOR-aligned incident reporting (separate from CDM but adjacent)
The 90-day free trial includes full access. Try the RAMS builder or start the free trial.
Frequently asked
Does CDM 2015 apply to homeowners?
The regulations apply to the construction work, but domestic clients are largely exempt from the client duties. Most domestic client duties transfer automatically to the contractor (single-contractor jobs) or the Principal Contractor (multi-contractor jobs).
What is the smallest project CDM 2015 applies to?
CDM 2015 applies to all UK construction work, regardless of size. Even a single-day job for one tradesperson is technically construction work covered by CDM 2015. The duties are proportionate to the risk, however - a small job has a much lighter documentation burden than a major project.
Do I need a CPP for a one-day job?
Strictly yes, if you are the contractor on a project with no Principal Contractor appointed. In practice, most small jobs have a brief CPP that fits on one or two pages. The principle is that the document is proportionate to the project.
Who is the Principal Contractor on a domestic extension?
If the homeowner has not formally appointed anyone, the Principal Contractor by default is whoever has the largest construction scope or who is coordinating the other contractors. This should be agreed in writing.
Are CDM 2015 prosecutions common?
Prosecutions are uncommon relative to the volume of UK construction activity, but the consequences when they happen are severe. HSE typically prosecutes when serious harm has occurred, when there is a clear pattern of negligence, or when warnings have been ignored. Six-figure fines are common in those cases.
Related guides
- What is a RAMS document? - the plain-English explainer
- RAMS template free UK 2026
- RAMS vs risk assessment - the difference
- Method statement examples UK 2026
Complys tracks every duty under CDM 2015 - documents, RAMS, worker competence, principal contractor declarations - in one platform. 90-day free trial.