Under FIDIC 2017, the contractor's entitlement to an extension of time is governed by Sub-Clause 8.5 (Extension of Time for Completion). The contractor must give notice under Sub-Clause 20.2.1 within 28 days of becoming aware of the event.
Qualifying events under FIDIC include: variations (Clause 13), Employer's risks (Clause 17), suspension by the Employer (Clause 8.9), and unforeseeable physical conditions (Clause 4.12). Each entitles the contractor to an extension of time and, in most cases, additional cost plus profit.
The formal claim must include: a detailed description of the event, the contractual basis for the claim, the cause-and-effect relationship between the event and the delay, a prospective or retrospective programme analysis, and quantification of any financial impact.
A critical requirement under FIDIC 2017 is the 28-day notice period under Clause 20.2.1. This is widely considered a condition precedent — failure to give timely notice may bar the claim entirely, although this is subject to the applicable law.