Last updated: 7 September 2026
Author: Jade Anderson, Senior Reporter, UK-Safety.News
Reading time: about 13 minutes

What this guide covers

• Why contractor management matters
• The law: CDM 2015 and who holds duties
• The dutyholders and what each must do
• Notification: when to send an F10
• The three documents
• Step by step: from appointment to handover
• Managing contractors outside construction
• Case study: the client who did not appoint a principal contractor
• Controls checklist
• Common mistakes
• Frequently asked questions
• Further resources

Construction remains the most dangerous mainstream industry in Britain. HSE’s figures for 2025/26 record 25 workers killed in construction, the highest of any sector and around a fifth of the 126 worker deaths across all industries that year.

Few of those deaths happen where one organisation has clear control. They happen where the interfaces are loose: a roofer working above a groundworks gang nobody told them about, a demolition crew handed a building with no asbestos survey, a scaffold altered by a trade that was never briefed. Contractor management is, at its core, the management of interfaces.

CDM 2015 places enforceable duties on clients, designers and contractors, and HSE prosecutes clients who treat the project as someone else’s problem. This guide is written for facilities managers, estates teams, site managers and anyone who commissions contractors alongside their day job.

The Construction (Design and Management) Regulations 2015 came into force on 6 April 2015. They apply to all construction work in Great Britain, from a two day shopfit to a new hospital, domestic or commercial. “Construction work” includes alteration, fitting out, repair, maintenance, redecoration, demolition and the installation or removal of mechanical and electrical services.

HSE’s guidance on the regulations is L153, Managing health and safety in construction, free to download. Two features of CDM 2015 catch organisations out:

• There is no small project exemption. Notification has a size threshold; the regulations themselves do not.
• Duties are triggered by the number of contractors, not the size of the job. As soon as more than one contractor is reasonably foreseeable, the client must appoint a principal designer and a principal contractor in writing. That includes a kitchen refit with a plumber and an electrician.

CDM sits alongside the Health and Safety at Work etc. Act 1974. A client who “leaves it to the contractor” has not transferred their own duty of care to the contractor’s workers or to anyone else affected by the work.

CDM 2015 identifies seven dutyholders. One organisation can hold more than one role, but every role must be filled on every project. The table summarises the main duties as set out in L153.

What happens if the client does not appoint

Regulation 5 is unforgiving. If the client fails to appoint a principal designer or a principal contractor, the client must carry out those duties itself. They do not lapse; they land on the client, usually the least equipped party to perform them. That is the point on which the case study below turns.

Competence: skills, knowledge, experience and organisational capability

Regulation 8 requires anyone appointing a designer or contractor to take reasonable steps to satisfy themselves that the appointee has the skills, knowledge and experience and, if they are an organisation, the organisational capability necessary to fulfil the role. L153 describes organisational capability as the policies and systems an organisation has in place to set acceptable health and safety standards, and the resources and people to make sure those standards are delivered.

Checking an organisation means its policy, risk assessment arrangements, training, supervision, accident and enforcement history and insurance. Checking an individual means qualifications, cards, training records and experience, then confirming on site that the person can do what the paperwork says.

Regulation 6 sets two independent tests. A project is notifiable if the construction work is scheduled to:

• last longer than 30 working days and have more than 20 workers working simultaneously at any point in the project; or
• exceed 500 person days.

Meeting either test makes the project notifiable. A 40 day refurbishment with a peak of eight workers fails the first test but may pass the second once you add up the person days.

Who, when and how. The client notifies (on a domestic project, the contractor or principal contractor, or the principal designer under a written agreement), as soon as practicable before the construction phase begins, using the online F10 form on hse.gov.uk; HSE no longer accepts paper, email or postal notifications. Railway work is notified to the Office of Rail and Road and nuclear or defence sites to the Office for Nuclear Regulation. Display the notice in the site office and update it if the particulars change. Notification changes nothing else: every other CDM duty applies whether or not the project is notified.

Pre construction information

The client must provide pre construction information to every designer and contractor appointed, or being considered for appointment, as soon as practicable (regulation 4). It covers the project and programme, the client’s management arrangements, known hazards such as asbestos, ground conditions, buried and overhead services and anyone still using the premises, plus any existing health and safety file. Handing a contractor a pre 2000 building with no asbestos survey is the most common and most dangerous failure here.

Construction phase plan

Before the construction phase begins, the principal contractor (or the contractor on a single contractor project) must draw up a construction phase plan (regulation 12). It sets out the health and safety arrangements and site rules and, where relevant, the specific measures for work involving particular risks listed in Schedule 3: aggravated risk of falls or burial, work near high voltage lines, risk of drowning, tunnels, diving, compressed air, explosives and heavy prefabricated components. It also covers welfare, emergency procedures and site security, and should be proportionate: a few pages for a small refurbishment, a full management document for a major scheme. The client must not let work start without it.

Health and safety file

Where there is more than one contractor, the principal designer must prepare a health and safety file containing what future construction, maintenance or demolition teams will need: residual hazards, the location of services, materials used and installed systems. It is handed to the client at the end of the project, kept available for anyone who needs it, and passed to a new owner if the building is sold.

Step 1: Define the work and decide the roles

Write down what you want done, where, when and alongside what else. If more than one contractor is foreseeable, appoint a principal designer and a principal contractor in writing before the construction phase starts. Assess notifiability and submit the F10 if needed.

Step 2: Pre qualify the contractor

Pre qualification is how you discharge the regulation 8 duty at organisational level. Many clients accept certification under a Safety Schemes in Procurement (SSIP) member scheme, or an assessment against the construction industry’s Common Assessment Standard, as evidence for the core health and safety questions. Treat these as a starting point: a certificate confirms the company has a policy and a system, not that the crew arriving on Monday has done this task before. Ask for job specific evidence: recent RAMS for similar work, training records for the people attending, accident and enforcement history, and employers’ liability insurance.

Step 3: Share pre construction information and hold a pre start meeting

Send the pre construction information with the tender, not on the first morning. Then walk the area together before mobilisation and agree access routes, isolations, storage, hot work rules, welfare, emergency arrangements and reporting lines. Record the meeting.

Step 4: Review the RAMS and the construction phase plan

Risk assessments and method statements should arrive before the work does, and someone competent on your side should read them. Check that they describe this job in this building, state the sequence of work, address the hazards in the pre construction information, specify the controls (which scaffold, which anchor point, which isolation) and name the people who will turn up. Reject a RAMS that could apply to any site in the country.

Step 5: Induct everyone and set up permits

Regulation 13 makes site induction a principal contractor duty; regulation 15 requires a contractor to provide one where the principal contractor has not. Cover site rules, the hazards of the premises, emergency procedures, welfare and who is in charge, and keep a signed record. Where work involves hot work, confined spaces, electrical isolation, fragile roofs, excavation or asbestos, use a permit to work so precautions are signed off before work starts and the area is handed back in a known state. See our guides to confined spaces and lock out tag out.

Step 6: Supervise and monitor

Supervision turns paperwork into behaviour. The contractor supervises their own workers; the principal contractor monitors the whole site; the client checks that both are happening. Walk the job at unpredictable times and stop work when what you see does not match the RAMS. Record contractor near misses and incidents in your own system: see our guide to reporting safety incidents.

Step 7: Control change

Most serious contractor incidents involve a departure from the plan: a different access method because the scaffold was late, an extra task added on the day, an unvetted subcontractor brought in to catch up. Agree that any change to scope, method, sequence, personnel or subcontractors needs a revised RAMS and sign off before it happens, and make sure the workers know the rule, not only the managers.

Step 8: Close out and hand over

Confirm the area is safe and isolations removed, check the principal designer has compiled the health and safety file, and review the contractor’s performance while it is fresh.

Cleaners, maintenance engineers, IT installers and waste collectors bring the same interface risks without necessarily triggering CDM. Two HSE publications cover this:

• INDG368, Using contractors: a brief guide, sets out five stages: identify the job; select a suitable contractor; make sure contractors know your hazards and your people know theirs; keep a check on the work; and review it afterwards.
• HSG159, Managing contractors: a guide for employers, was written for small and medium sized companies in the chemical industry but is useful for any organisation with contractors on a working site.

The legal footing is the Health and Safety at Work etc. Act 1974 and the Management of Health and Safety at Work Regulations 1999, which require employers sharing a workplace to cooperate, coordinate and exchange information on the risks. The toolkit is the CDM process minus the formal appointments: define the job, check competence, exchange information, induct, permit high risk tasks, supervise, review. Visiting drivers are covered in our workplace transport guide.

In September 2023 an HSE inspector visited a demolition site in Cannock where work had stopped after asbestos was found; a survey identified around 218 square metres of asbestos containing materials. An earlier management survey had already identified asbestos and had been shared with the demolition contractor, which went ahead regardless. An unlicensed company and its director then carried out an illegal asbestos clearance, exposing workers and the public.

The client, Sohan Group Limited, had not appointed a principal contractor. Under regulation 5(4) that meant the client itself was responsible for planning, managing and monitoring the construction phase, a duty it had neither recognised nor performed. At Birmingham Magistrates’ Court on 6 March 2026 the client pleaded guilty to breaching regulation 5(4) and was fined £74,900 with £3,658.14 costs. The demolition contractor, Maize Metals Limited, pleaded guilty to breaching regulation 15(2), the duty to plan, manage and monitor its own work, and was fined £13,400 with £1,359.51 costs. The individual who ran the clearance received a 26 week prison sentence suspended for two years, a curfew and a five year director disqualification.

What it shows. No principal contractor meant no one coordinating the demolition against the survey findings. A known hazard was passed on but nobody checked it had been acted upon. An unvetted party was brought in to fix the problem, exactly the uncontrolled change described in Step 7. The client’s fine was more than five times the contractor’s: courts expect the organisation that commissions the work to control it.

Every row should have a named owner and evidence you could show an inspector.

• Assuming CDM does not apply to small jobs. It applies to all construction work. Only notification has a size threshold.
• Not appointing in writing. A verbal understanding that “the builder is in charge” is not an appointment. Without it, the client holds the principal contractor’s duties.
• Accepting generic RAMS. If the method statement does not mention your building, your services or your asbestos survey, it was not written for your job.

• HSE: CDM 2015 summary of duties
• HSE: L153 Managing health and safety in construction
• HSE: F10 notification of a construction project
• HSE: INDG368 Using contractors, a brief guide
• HSE: HSG159 Managing contractors, a guide for employers
• legislation.gov.uk: Construction (Design and Management) Regulations 2015
• HSE: Work related fatal injuries in Great Britain
• UK-Safety.News: Asbestos in the Workplace
• UK-Safety.News: Useful Documents

This guide is general information for Great Britain and is not legal advice. Check the current HSE guidance before acting on a specific case.

About the author: Jade Anderson specialises in turning regulations into practical steps for supervisors and safety leads.