Uniform Building Contractors Ltd v WASA (Trinidad and Tobago) [2026] UKPC 2 – A Privy Council decision on FIDIC Yellow Book variations and notice 9 February 2026

UBC contended that each was a variation instructed or approved by the engineer. WASA denied that any of these items constituted variations and argued that, even if they did, UBC had failed to comply with the mandatory contractual procedures for claiming additional payment.

The Court of Appeal found for UBC, holding that the engineer had treated the four items as variations and that WASA had waived strict compliance with notice provisions. WASA appealed to the Privy Council.

UBC advanced its claims on the basis that the four items constituted variations under clause 13 of the FIDIC Yellow Book. It relied heavily on evidence from the engineer, Mr Paul, who asserted that he had approved the disputed works as variations. UBC contended that these items arose out of practical necessity during execution and thus fell outside the originally envisaged scope of works.

UBC further argued that, even if written notices were required under the contract, WASA had waived such requirements through its conduct, including its acceptance of the engineer’s guidance on site and its awareness of the additional costs incurred through increased material prices. The contractor also maintained that the strict FIDIC notice machinery no longer applied once the works had been terminated.

WASA resisted these claims on two principal bases. First, WASA maintained that none of the four items constituted a variation within the meaning of the contract. It argued that the Employer’s Requirements and Bill of Quantities contemplated excavation in any material encountered, disposal of unsuitable material, importation of suitable backfill, and the possibility of night working subject to noise restrictions.

Second, WASA submitted that, even if any of the disputed items were variations, UBC had failed to comply with the mandatory variation and claims procedures under clauses 13 and 20.1. These included the need to issue notices within the 28‑day window provided in clause 20.1 and the requirement to submit proposals and obtain determinations under clause 3.5. WASA argued that these requirements constituted a contractually binding condition precedent to entitlement. It denied any waiver or estoppel and denied that the engineer had authority to amend or waive contractual requirements.

Legal points considered by the Board

The Privy Council examined four central questions: (i) whether the four items were variations as defined under the FIDIC contract; (ii) whether UBC had complied with the variation procedure; (iii) whether UBC had failed to comply with a condition precedent by not issuing notice under clause 20.1; and (iv) whether the Court of Appeal was correct to rely on notions of fairness and waiver.

On variations, the Board held that the Court of Appeal had erred by failing to analyse the contract terms. The construction of a variation turns primarily on whether the alleged instruction changes the Employer’s Requirements, or the Works as defined. The Board emphasised that, under a design‑and‑build lump‑sum contract, the contractor bears the risk of the sufficiency of its design and pricing. It concluded that cutting the asphalt roadway, disposing of unsuitable material, importing backfill and undertaking night work were all activities expressly or impliedly included within UBC’s contractual scope. For that reason, they were not considered as variations.

Thirdly, contractors must avoid relying on retrospective arguments of fairness or project exigencies. The fact that work was performed in good faith, or that an engineer indicated that claims would be considered later, cannot circumvent express contractual machinery. Particularly under design‑and‑build forms, contractors must take great care in documenting instructions, issuing Confirmation of Verbal Instruction (COVI) notices and ensuring that variation procedures are meticulously followed.

Fourthly, the case highlights the commercial danger of commencing additional or changed work without first securing clear and contractually compliant instructions. In the UK context, where variations and claims can easily involve sums vastly exceeding those in dispute in this case, failure to issue notices may expose contractors to catastrophic financial consequences.

Finally, the decision reinforces the importance of contemporaneous documentation. The Privy Council placed significant weight on the paucity of contemporaneous records in rejecting UBC’s claims. UK contractors should view this as a reminder of the value of disciplined project administration, especially under FIDIC, NEC and other forms that translate real‑time procedural compliance into entitlement.