The Construction (Design and Management) Regulations 2015 apply to every construction project in Great Britain, from a domestic extension to a hospital. They put named duties on six duty holders: the client, the principal designer, the principal contractor, designers, contractors and workers. Where more than one contractor is involved at any time, the client must appoint a principal designer and a principal contractor in writing; if it fails to, it carries those duties itself.
The principal designer plans, manages, monitors and coordinates health and safety in the pre-construction phase: assembling pre-construction information for the people who will build the job, making sure designers eliminate and reduce foreseeable risk, and preparing the health and safety file that is handed to the client at the end. The principal contractor carries the same duties for the construction phase, and every project, however small, needs a construction phase plan before work starts.
A project is notifiable to the Health and Safety Executive on an F10 where construction work is scheduled to last more than 30 working days with more than 20 workers on site at the same time, or to exceed 500 person days. Notification changes nothing about the duties themselves; they apply to the un-notified job too. On site, the regulations are only as good as the people applying them: the site inductions, the reviewed RAMS, the inspections at the prescribed intervals and the subcontractors whose competence somebody actually checked.