Plain-language explanations of key terms — for engineers and project managers, not lawyers.
Sub-surface or physical conditions encountered during the works that an experienced contractor could not reasonably have foreseen at the time of tendering. Under FIDIC Red Book Sub-Clause 4.12, if a contractor encounters unforeseeable physical conditions, it is entitled to an extension of time and additional payment. This provision is significantly limited or excluded in the FIDIC Silver Book. Site investigation before tendering is critical to managing this risk.