6 questions answered · Updated 5 March 2026
Common questions about CDM 2015 regulations answered clearly. Covers duty holder roles, construction phase plans, F10 notifications, and compliance requirements.
CDM 2015 applies to ALL construction work in Great Britain, regardless of size or duration. There is no minimum threshold — even a single-person job fitting a kitchen is covered. However, certain additional duties apply when a project has more than one contractor (a principal designer and principal contractor must be appointed) or when the project is notifiable to the HSE (lasting longer than 30 working days with more than 20 workers simultaneously, OR exceeding 500 person-days of construction work).
The principal designer is responsible for planning, managing, monitoring, and coordinating health and safety during the pre-construction phase — they focus on design risk management and ensuring designers eliminate or reduce risks through design choices. The principal contractor is responsible for planning, managing, monitoring, and coordinating health and safety during the construction phase — they manage the physical site, coordinate contractors, and ensure the construction phase plan is followed. Both are appointed by the client.
You need to notify the HSE using an F10 form if your construction project will last longer than 30 working days AND have more than 20 workers on site at any one time, OR exceed 500 person-days of construction work in total. The notification must be submitted as soon as practicable before the construction phase begins. The principal contractor or client (if no PC is appointed) is responsible for displaying the F10 on site.
Under CDM 2015 Regulation 12, the construction phase plan must include: a description of the project, the management structure and responsibilities, health and safety aims, site rules, arrangements for controlling significant risks (working at height, excavations, traffic management, etc.), arrangements for the delivery and storage of materials, fire prevention and emergency procedures, welfare arrangements, and arrangements for monitoring compliance. The plan must be proportionate to the risks and complexity of the project.
Yes, under CDM 2015, if the client fails to appoint a principal contractor on a project with more than one contractor, the client assumes the duties of the principal contractor by default (Regulation 5(3)). However, the client must be competent to fulfil these duties. In practice, this is rarely advisable for domestic or commercial clients. The client's duties under CDM 2015 cannot be delegated — they always retain overall responsibility for ensuring the project is managed safely.
Penalties for CDM 2015 non-compliance can be severe. The HSE can issue improvement notices, prohibition notices (stopping work immediately), or prosecute. Fines are based on the Sentencing Council guidelines: for organisations, fines start at Category 4 (lower culpability, low harm risk) at around GBP 1,000-4,000 and can reach Category 1 (high culpability, death or serious injury) at GBP 300,000-10,000,000+. Individuals can face unlimited fines and up to 2 years imprisonment under Section 33 of the Health and Safety at Work Act 1974.