CDM 2015 duty holders, explained.

The designer the client appoints in writing to control the pre-construction phase, where more than one contractor will work on the job (regulation 5 of CDM 2015). The appointment must be made as soon as practicable, and before the construction phase begins. HSE says the principal designer can be an organisation or, on smaller projects, an individual, with the skills, knowledge and experience for the role.

A commercial client must then carry out those duties themselves (regulation 5 of CDM 2015). On a domestic job the roles fall to others instead: the designer in control of the pre-construction phase is the principal designer, and the contractor in control of the construction phase is the principal contractor (regulation 7). Either way, the duties do not go away.

Yes, if construction work is likely to be done on them. HSE says count every day on which construction work is likely to be carried out, even if only for a short time, including weekends and holidays. A project is notifiable if it is scheduled to last longer than 30 working days with more than 20 workers at the same time at any point, or to exceed 500 person days (regulation 6 of CDM 2015).

Yes. The notice sent to HSE must be clearly displayed in the construction site office, in a form any worker on the job can read and understand, and updated if necessary (regulation 6 of CDM 2015). The client sends it as soon as practicable before the construction phase begins. On a domestic job this normally passes to the contractor or principal contractor (regulation 7).

No. HSE says a health and safety file is only needed on projects involving more than one contractor (L153). The principal designer prepares it and passes it to the client at the end of the project (regulation 12 of CDM 2015). The client must keep it available for anyone who may need it, and hand it on if they sell or otherwise dispose of their interest in the building (regulation 4).

No, the role no longer exists. CDM 2015 removed the CDM co-ordinator role from CDM 2007 and replaced it with the principal designer (L153). A former CDM co-ordinator cannot automatically act as principal designer: HSE says the principal designer must be a designer, in control of the pre-construction phase, with the right skills, knowledge and experience for the project.

Yes, if it counts as construction work. That includes the repair, upkeep, redecoration and other maintenance of a structure, and installing, maintaining or repairing services fixed within or to a structure, such as electrical, gas or telecommunications services (regulation 2 of CDM 2015). HSE says CDM does not apply to all maintenance work, so check the definition if you are unsure.

Anyone who, as part of a business, prepares or changes a design for a structure, or arranges for someone under their control to do so (regulation 2 of CDM 2015). Designs include drawings, specifications, bills of quantities and calculations. HSE says designers include architects, engineers and quantity surveyors, and also contractors, tradespeople and commercial clients who carry out design work.