From a Royal Institute of the Architects of Ireland (RIAI) e-mail:
Q.3 Does my client have to appoint a Project Supervisor Construction Stage (PSCS) for a domestic project going on site after the 1st August 2013, where I have already done the design work?
No. The revised regulations are not and cannot be retrospective. The requirement to appoint a PSCS applies only to projects where the design process commences on or after 1 August 2013. Informal conversations with the H.S.A. have confirmed this. Please note if a project runs on for a period of 12 months, or more, after 1st August 2013, then there is an obligation to appoint a PSDP and a PSCS after the 12 month period.
From the HSA web site:
What if I've started my construction work prior to the effective date?
The requirements/obligations under these Regulations are applicable for all construction projects on homes which commence on or after 1st August 2013. If the design or construction stage of a project has started prior to the effective date then the duties of the client with regard to appointing project supervisors do not apply for a period of 12 months.