What counts as a variation

Scope is element 1 of a variation claim: proving that the contract did not already oblige the contractor to do this work. It is the element most often assumed rather than pleaded. The remaining four elements (instruction, procedural compliance, valuation, and survival of whatever release came afterwards) are set out in the five-element anatomy of a variation claim.

Everything below is about entitlement in principle. It is deliberately silent on whether anyone actually instructed the work, which is a separate battle and usually the harder one.

Is it a variation? The contract decides, not the conduct on site

Whether an item of work is a variation is a question of construing the contract documents. In Uniform Building Contractors Ltd v Water and Sewerage Authority of Trinidad and Tobago [2026] UKPC 2 (22 January 2026), Sir Peter Coulson held at [15] that "whether or not an item of work is a variation is primarily a function of the contract terms", and that the court below had erred by reasoning from how the parties had behaved on site.

The facts are ordinary, which is what makes the decision useful. An amended FIDIC Yellow Book 1999 lump-sum design-and-build contract for a 28.43 km pipeline. The contractor claimed roughly TT$13.91m for four items it said the Engineer had instructed orally as variations: asphalt cutting and roadway reinstatement, disposal of unsuitable material, importation of backfill, and night work. The Engineer never issued a determination. None of the four items was a Variation. Each fell within the lump-sum obligations on the true construction of the contract.

Two further holdings travel with the scope point. Clause 3.1 of that contract gave the Engineer "no authority to amend the Contract". The role is administrative and certifying, so only the parties can waive, not the contract administrator. And the Court of Appeal's approach, that flexible operation on site precluded strict enforcement of the machinery, was rejected outright.

Flexibility on site is evidence of flexibility on site. It is not evidence of what the contract required.

Most commentary reads UBC v WASA as a time-bar case, because the Board also held Sub-Clause 20.1 of the 1999 form a condition precedent in "classic condition precedent form" at [64]. The scope holding is the more useful half, and it applies whatever the form. Note its limits honestly: the decision is on the 1999 FIDIC edition, the Board's remarks on the procedural issues are partly obiter, and a Privy Council appeal from Trinidad and Tobago binds no arbitral tribunal elsewhere. It is nonetheless the highest common-law statement of the scope test currently available.

Underestimating the work is not a variation

Work that is expressly or impliedly included in the work for which the lump sum is payable is not a variation, however badly the contractor underestimated it. Under a lump sum the contractor undertakes the outcome, and the risk of the quantity, the difficulty and the method sits with it. That was the second holding in Uniform Building Contractors Ltd v Water and Sewerage Authority of Trinidad and Tobago [2026] UKPC 2, applying a nineteenth-century principle drawn from Sharpe v San Paulo Railway Co (1873).

That authority is worth handling carefully. The report reference commonly given for Sharpe (LR 8 Ch App 597) has not been verified against the primary report in this corpus, so cite the case by name and year and check the report before it goes into a pleading. The principle itself is not in doubt and was applied by the Board in 2026.

The mirror image is equally settled: work wholly outside the original scope is not a variation either, because it falls outside the change mechanism altogether and takes effect as a separate contract, Blue Circle Industries plc v Holland Dredging Co (UK) Ltd (1987) 37 BLR 40 (CA). A variation power is a power to adjust the bargain, not to make a new one. Between those two boundaries sits everything that is actually argued.

Lump sum or remeasurement: the same physical facts, opposite answers

The clearest demonstration that scope is a contractual question, not a factual one, is that identical ground conditions produce opposite entitlement under two different pricing structures. Thirty per cent more excavation than tendered is the contractor's loss under a lump sum and a routine measurement adjustment under a remeasurement contract. Nothing about the excavation changed. The contract did.

The thresholds are express and they are arithmetic, so run them before pleading anything. Under FIDIC Red Book 2017 (reprinted 2022), Sub-Clause 12.3 a new rate is appropriate where either all four of the following are satisfied: a measured quantity differing by more than 10% from the Bill, the change multiplied by the rate exceeding 0.01% of the Accepted Contract Amount, a direct change in Cost per unit of more than 1%, and the item not being specified as a fixed-rate item: or the work is instructed under Clause 13, no rate is specified in the Contract, and no specified rate is appropriate because the work is not of similar character or not executed under similar conditions. That second limb is the route for a contractor whose arithmetic fails. The four arithmetic conditions are reported consistently across commentaries but the verbatim sub-clause text has not been read in this corpus. Treat the substance as reliable and verify the wording before quoting it. Under FAR 52.211-18 (Variation in Estimated Quantity) an equitable adjustment is available where the actual quantity varies by more than ±15%, on the demand of either party, and is confined to cost differentials directly attributable to the deviation beyond 15%, Victory Construction Co. v United States (Ct. Cl. 1975), reaffirmed in Foley Co. v United States (1993). Private contracts commonly set the figure at 25%.

JCT does not route quantity change through the change definition at all. Under JCT Standard Building Contract 2024 it arises through Approximate Quantities, and under JCT Design and Build 2024 (which has no bills) it arises only through provisional sums.

Design development or design change?

On a design-and-build or EPC contract the test is whether the design work merely filled in what the Employer's Requirements already required, or went beyond them. If the design development solely fills in the blanks, it is design development, and design development is what the contractor was paid for. If it goes beyond the Employer's Requirements, it is a design change and capable of being a variation. The baseline is the Employer's Requirements, not the drawings, and not the tender assumptions.

Say plainly what the authorities do and do not do. There is no case establishing a general test for this boundary. The English decisions are fact-specific applications, and they run against contractors more often than not:

• Co-operative Insurance Society Ltd v Henry Boot Scotland Ltd [2002] EWHC 1270 (TCC). An obligation to "complete the design" means developing a preliminary or scheme concept into a constructable design. That is design development, not variation.
• Workman Properties Ltd v ADI Building and Refurbishment Ltd [2024] EWHC 2627 (TCC) (21 October 2024): on an amended JCT Design and Build 2016, an Employer's Requirements recital that the design "has been developed to date which has been taken to end of RIBA Stage 4" was "nowhere near sufficient" to cut down bespoke clauses making the contractor "fully responsible" for design. A statement about design maturity is descriptive, not a warranty of completeness.
• Skanska Construction UK Ltd (formerly Kvaerner Construction Limited) v Egger (Barony) Ltd [2004] EWHC 1748 (TCC) (HHJ David Wilcox, 30 July 2004). The line is drawn item by item, not project by project: a second water main was a design change because the Employer's Requirements specified one, while additional steelwork design was development within the contractor's assumed design risk. This is the first judgment between these parties. A second exists at [2005] EWHC 284 (TCC) and is not the one relied on here. Report-series citations for the decision conflict across secondary sources.

So the test is built from the level of definition in the Employer's Requirements, and it has to be, because there is no case law that would let it be built any other way. In practice that means one of two pleadings works and the rest do not. Either an ER performance requirement changed (identify the capacity, rating, tolerance or standard in the Employer's Requirements and show the instructed outcome differs) or the ERs positively specified X and Y was instructed, as with the Skanska water main. Both anchor to a clause. If you cannot point to the clause, you probably have design development.

Under JCT Design and Build 2024 the underlying risk allocation is not a simple hierarchy: clause 2.11 provides that the contractor is not responsible for verifying the adequacy of design in the Employer's Requirements, while clause 2.17.1 imposes reasonable skill and care on the Contractor's Proposals design. Two pathologies dissolve that allocation: documents dual-labelled as both ER and CP, so neither regime applies cleanly, and Contractor's Proposals that merely restate "we will comply with the Employer's Requirements", which collapses the allocation entirely. Where a bespoke order-of-precedence clause is bolted on, it frequently conflicts with JCT's own discrepancy machinery, and no leading English authority on that conflict has been located.

One FIDIC drafting check belongs here. FIDIC 2017 changed Sub-Clause 4.1 so that fitness is for the purposes "as defined and described in the Employer's Requirements". The structural consequence is that a Variation must specifically amend the Employer's Requirements if it is to alter the fitness-for-purpose obligation. On any Yellow or Silver Book variation touching performance, check whether the instruction amends the ERs, and if it does not, ask for it to.

Provisional sums are instructed and valued, but not always varied

A provisional sum is a contractually embedded allowance the employer may instruct to be expended or omitted. Expenditure is valued, not varied. Instructions are issued under JCT Standard Building Contract 2024 clause 3.16 and JCT Design and Build 2024 clause 3.11 ("Instructions on Provisional Sums"), and under FIDIC Red Book 2017 (reprinted 2022) Sub-Clause 13.4. The valuation looks identical to a variation: JCT Design and Build 2024 clause 5.2 and JCT Standard Building Contract 2024 clause 5.2 both apply the same Valuation Rules to Changes and to provisional sum work, but the entitlement analysis is not the same, because nobody has to prove the work was outside the scope. The contract expressly anticipated it.

Where these disputes are actually decided is the defined/undefined classification under RICS NRM2, October 2021, reissued October 2022 as RICS practice information (previously SMM7), because that classification, not the valuation rule, determines what happens to time and preliminaries. The table below states form-default positions: bespoke amendment to these provisions is normal on major projects, and the executed contract governs.

Form-default. The JCT 2024 suite read with the NRM2 rules of measurement. The time and preliminaries rows are the ordinary consequence of the classification, not a clause. Bespoke amendment is normal, and the executed contract governs.

The programme consequence follows directly from the definition status, which is why a contractor pricing a tender should treat the defined or undefined status of every provisional sum as a commercial decision rather than a measurement formality. The precise sub-clause locations of the corresponding Relevant Events and Relevant Matters in the JCT 2024 suite have not been verified in this corpus and should be checked against the printed form before they are cited.

Two practical points. Arbitrarily omitting provisional sum work in order to give it to another contractor is a breach, Amec Building Ltd v Cadmus Investment Co Ltd (1996) 51 Con LR 105. And a contract carrying provisional sums across most of its scope is not a priced contract. It is a cost-plus contract with a cover sheet, and it should be priced and programmed as one.

Before pleading anything, run three questions in order. Is the work described in the contract documents? If yes, is it covered by a provisional sum or an approximate quantity: in which case it is an expenditure or remeasurement question, not an entitlement question? And is it simply the same work in a different amount, in which case run the form's threshold arithmetic first? Getting this wrong costs money in both directions, and it changes which rung of the valuation hierarchy the work is priced on.

Omission is a variation too, until it becomes a breach

Every mainstream variation clause permits the employer to omit work, and a valid omission is a variation valued as a deduction. The limit is the purpose of the power: an employer may omit work, but may not omit work in order to give it to someone else, including itself, absent express words of the clearest kind. Carr v J A Berriman Pty Ltd (1953) 89 CLR 327 (HCA) is the leading authority, structural steel reassigned to a third party in purported reliance on the omission power was a breach amounting to repudiation. Abbey Developments Ltd v PP Brickwork Ltd [2003] EWHC 1987 (TCC) states the principle generally: a variation power must be exercised for the purpose for which it was granted, and the contractor has the corresponding right to complete the work it contracted to carry out.

The forms diverge. FIDIC Red Book 2017 (reprinted 2022) Sub-Clause 13.1(d) codifies the common-law rule expressly, permitting omission of any work "unless it is to be carried out by others". JCT Design and Build 2024 and JCT Standard Building Contract 2024 allow omissions to be valued but contain no provision permitting redistribution, so the common-law rule fills the gap. NEC4 ECC is silent, which is why redistribution requires an express Z-clause. AS 4000:2025 is reported to run the other way, expressly permitting omission of work whether or not it is to be performed by others. A material departure from the Carr v Berriman default that should be checked against the printed standard on any Australian contract before wrongful omission is pleaded.

There is a corollary in Carr v Berriman that gets overlooked and matters for pleading: the variation power operates only where the power to vary is actively exercised, not where the contractor is simply told the work has gone elsewhere. An employer who says "we have given that to someone else" has not instructed an omission at all. The contractor's case is then not "value my omission properly" but "there was no valid omission, and I have been deprived of work I contracted to perform".

The cut-off: an instruction given too late is not a variation

A variation must be instructed before the contractual window closes, and that window can shut well before the final account. FIDIC Red Book 2017 (reprinted 2022) Sub-Clause 13.1 permits Variations only before the issue of the Taking-Over Certificate. AS 4000 requires the direction before the Date of Practical Completion, and the 2025 edition moved that date in substance, because Practical Completion can now occur before its certificate issues, so the window may close earlier than the paperwork suggests. AS 4000:2025 is a paid Standards Australia publication that has not been read in full for this corpus, so the clause numbers are deliberately not given here. Take them from the printed standard.

In Qatar the point is statutory rather than merely contractual. Under the Civil Code (Law No. 22 of 2004), variation clauses generally cease to operate after completion, and instructions given after completion constitute a separate agreement requiring independent pricing. A FIDIC Sub-Clause 13.1 instruction issued after the Taking-Over Certificate is therefore doubly problematic on a Qatari project. The contract has already exhausted the power, and the local law treats what follows as a new contract. The specific article numbers of the Qatari Civil Code have not been verified in this corpus and should not be pleaded without checking the code.

The cut-off interacts with a definitional trap that catches contractors on FIDIC work in particular. The 2017 definition of a Variation is a change to the Works "instructed as a variation under Clause 13", a definition that refers to itself through the instruction. The 1999 definition read "instructed or approved". The 2017 edition deleted "or approved", closing off the retrospective-blessing route. Informal approval of work by the Engineer is not approval as a variation, which is precisely what defeated the contractor in Uniform Building Contractors Ltd v Water and Sewerage Authority of Trinidad and Tobago [2026] UKPC 2, and it is why arguments that scope was changed without anyone instructing a variation have to be run on a different footing altogether.

Which is the practical end of this analysis. Establishing that an item is, on the true construction of the contract, outside the priced scope wins element 1 and nothing else. The work still has to have been instructed in the required form, by the person with authority, inside the window, and where the contract's own procedure was never followed, the full claims machinery and its condition precedents apply instead, which is exactly when the contractor least wants to meet them.

À propos de ce contenu Le contenu de la bibliothèque est une information générale sur la pratique des réclamations de construction, et non un avis juridique. Le droit à réclamation, les délais et la procédure sont régis par votre propre contrat et par le droit du lieu où les travaux sont exécutés. Révisé le 7 août 2026 · Signaler une correction