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What Is CDM? — Construction Design and Management
A plain-English guide to CDM 2015: duty holders, the F10 notification, the construction phase plan, and how CDM applies to domestic and commercial projects.
Definition
CDM (Construction (Design and Management) Regulations 2015) is the main set of regulations for managing health, safety, and welfare on construction projects in Great Britain. CDM 2015 replaced the earlier CDM 2007 and applies to all construction work, including domestic projects, commercial developments, and civil engineering. The regulations place duties on clients, designers, and contractors to plan, manage, and coordinate health and safety throughout a project.
When Is It Used?
CDM applies from the earliest design stage through to project completion and handover. A principal designer must be appointed on projects with more than one contractor, and a principal contractor must manage the construction phase. Even small domestic projects (a single contractor fitting a kitchen, for example) require the contractor to have a construction phase plan proportionate to the risks involved.
Key Facts
- CDM 2015 applies to all construction projects in England, Scotland, and Wales
- F10 notification required if project exceeds 30 days with 20+ workers, or 500+ person-days
- A construction phase plan must be in place before work starts on site
- Principal designer must be appointed on multi-contractor projects
- Welfare facilities (toilets, washing, rest area, drinking water) must be provided from day one
- Designers must eliminate or reduce hazards through design choices (designing out risk)
- The health and safety file must be handed to the client at project completion
- Enforcement is by the HSE, with powers to issue improvement/prohibition notices and prosecute
Related Calculators
Use the Project Profit Calculator to budget for CDM compliance costs, or the Scaffolding Calculator for safe access planning. The Skip Hire Cost Calculator helps with waste management planning required by CDM.
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Frequently Asked Questions
Yes. Since CDM 2015, the regulations apply to ALL construction projects including domestic work for homeowners. However, on domestic projects, the client (homeowner) duties are automatically transferred to the contractor (or principal contractor if there is more than one contractor). The homeowner is not expected to manage health and safety themselves, but the contractor must ensure a construction phase plan is in place.
An F10 is the notification form that must be sent to the Health and Safety Executive (HSE) before work begins on a project that will last longer than 30 working days with more than 20 workers at any one time, OR will exceed 500 person-days of construction work. The F10 must be submitted by the client (or the principal designer on their behalf) as soon as practicable before the construction phase begins.
CDM 2015 identifies five duty holders: the Client (who commissions the work), the Principal Designer (who plans, manages and coordinates the pre-construction phase health and safety), Designers (who prepare designs for construction), the Principal Contractor (who plans, manages and coordinates the construction phase), and Contractors (who carry out or manage construction work). On single-contractor projects, the contractor takes on the principal contractor role automatically.
A Construction Phase Plan (CPP) is a document prepared by the principal contractor (or sole contractor) setting out how health and safety will be managed during the construction phase. It must be in place before construction begins and should cover: site description, management structure, arrangements for controlling significant risks, site rules, emergency procedures, and welfare arrangements. The level of detail should be proportionate to the risks.
The health and safety file is compiled by the principal designer and handed to the client at the end of the project. It contains information needed for future maintenance, repair, renovation, or demolition of the building. This includes as-built drawings, details of hidden services, structural design information, hazardous materials used, and operation and maintenance manuals. The client must keep the file and make it available to anyone who needs it for future work.
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Last updated: March 2026
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