The Construction (Design and Management) Regulations 2015 are legislation about protection of health and safety in connection with the design, construction, maintenance and eventual demolition of buildings. Read more here at the HSE website.
They apply to construction of all buildings including extensions to private homes and new houses. If you are the client for construction, and it involves more than one tradesperson (so it is not a one-off repair, for example) you have certain duties. Key amongst them is a duty to appoint a Principal Designer (PD) and a Principal Contractor (PC).
On a project to extend your home, if you do not appointment a PD, then the designer you appoint will automatically become the PD. (And the builder you employ automatically becomes the Principal Contactor). Both PD and PC have no choice but to accept their roles. And carry out their duties in them.
