Written instruction and waiver

Formality is element two of the five-element variation claim, and, across the decisions gathered in this corpus, it kills more claims than any other element. The standard architecture is that a variation is compensable only if it is instructed, in writing, by the named person, before a cut-off, usually practical completion or taking over. Each limb fails independently. Contractors argue about whether they were instructed and lose on writing, on authority, or on timing.

Before any of that matters, the work has to have been outside the contract scope at all. That is a separate question about what the contract already required, and it is worth settling first, because a formality argument about work the contractor was always obliged to perform is wasted effort.

I did the work and there is no written instruction. Is the claim dead?

It depends on the regime, and the spread is the widest in this corpus. England enforces the formality and treats the JCT writing requirement as a condition precedent. Australia never adopted Rock Advertising at all. Canada permits waiver on a paid course of dealing. The United States splits internally: private work is the most permissive regime surveyed, public work close to the strictest.

Jurisdictional. Every row rests on appellate authority (UKSC, Tenth Circuit, Federal Circuit, Ontario Court of Appeal, High Court of Australia, Privy Council) except Vainker, which is first instance in the TCC.

Two cautions on the civil-law row. The first is that France is the counter-example: the marché à forfait rule in Code civil art. 1793 requires the employer's written authorisation for additional works on a lump-sum building contract for a landowner: a statutory formality stricter than FIDIC's, and one that survives contrary contractual drafting. The second is an edition alert. The UAE replaced Federal Law No. 5 of 1985 with Federal Decree-Law No. 25 of 2025. The muqawala provisions moved from Articles 872–896 to 812–839 and the lump-sum rule from Article 887 to Article 829. Whether new Article 829 reproduces the substance of the old rule could not be verified. Every UAE variation memorandum written before 2026 should be treated as potentially out of date.

Why the American answer flips completely on the public/private line

Identify whether the work is public or private before anything else, because in the United States nothing else in the analysis survives that line. On private work a writing requirement can be waived by conduct, "the parties to a written contract are as free to alter it after it has been made as they were to make it". On public work the requirement is frequently not a formality at all but a limit on the contracting officer's capacity, and estoppel cannot cure a capacity defect.

The private-work rule is well populated. Sitkin v Smith, 35 Ariz. 226, 276 P. 521 (1929) found the parties had "disregarded the contract" and consented to waive the condition. Cardinal Development Co v Stanley Constr. Co, 497 S.E.2d 847 (Va. 1998) required a pattern of conduct plus payment, on a standard of clear, unequivocal and convincing evidence. Udevco, Inc v Wagner, 678 P.2d 679 (Nev. 1984) went further and treated oral directives alone as waiver regardless of subsequent payment. Menard & Co Masonry Building Contractors v Marshall Building Systems, Inc, 539 A.2d 523 (R.I. 1988) found "don't worry about it, you'll be paid" sufficient. Pioneer Roofing Co v Mardian Constr. Co, 152 Ariz. 455, 733 P.2d 652 (App. 1986) held emergency conditions waive the requirement.

On public work the reasoning changes shape. In California, waiver and estoppel are not available against a public entity at all, on the public-policy ground that the interest in limiting a public entity's contractual obligations outweighs them, the clearest verified strict rule in the material. In Ohio, Foster Wheeler Enviresponse, Inc v Franklin County Convention Facilities Authority, 78 Ohio St. 3d 353, 678 N.E.2d 519 (1997) held that an engineer or architect cannot waive the written-order requirement absent express authority, even where authorised to approve changes in writing. In Arizona, Kaman Aerospace Corporation v Arizona Board of Regents, 217 Ariz. 148, 171 P.3d 599 (App. 2007) held public entities bound only by agents with actual authority: a sharp public/private split inside a single state, given O'Malley Investment & Realty Co v Trimble, 5 Ariz. App. 10, 422 P.2d 740 (1967) on the private side.

On American public work the writing requirement is not a formality but a limit on the officer's capacity to contract, and estoppel will not create authority the legislature withheld.

That is why some states describe the requirement as jurisdictional. Treatment as jurisdictional is verified here for California, Ohio and Arizona only. Practitioners routinely add New York and Texas to that list. Neither could be verified in this research pass, and neither should be asserted without independent checking. Two adjacent evidential markers are worth carrying: the Seventh Circuit requires waiver of an anti-waiver clause to be proved by clear and convincing evidence, Wisconsin Electric Power Co v Union Pacific R.R. Co, 557 F.3d 504 (7th Cir. 2009), and the Court of Federal Claims requires "strong evidence of implied waiver", Public Service Co v United States, 91 Fed. Cl. 363 (2010).

On federal work the gap is filled not by waiver but by the constructive change doctrine, which substitutes for authority through the Contracting Officer's actual or imputed knowledge. FAR 52.243-4(b) treats any other written or oral order from the Contracting Officer that causes a change as a change order, provided the Contractor gives written notice of the date, circumstances and source and states that it regards the order as a change order. FAR 52.243-4(c) is the exclusivity provision: except as provided in the clause, no order, statement or conduct of the Contracting Officer is to be treated as a change. The (b) notice is the gateway, not housekeeping.

England and Wales after Vainker: writing as a condition precedent

Brenda Vainker & Anor v Marbank Construction Ltd & Ors [2024] EWHC 667 (TCC) is the first English decision to hold the JCT written-instruction requirement squarely a condition precedent to valuing a variation. It was decided on a JCT Standard Building Contract Without Quantities 2011 with amendments and a Contractor's Designed Portion, and it is a first-instance decision. The reasoning is textual and travels to the 2024 forms: only variations instructed in writing or confirmed under the confirmation clause fall to be valued, the Contract Sum may not be adjusted otherwise than in accordance with the express provisions, and variations enter the account only through valuation. There is no alternative mechanism for adjusting the Contract Sum.

Waiver is hard in England because of Rock Advertising Ltd v MWB Business Exchange Centres Ltd [2018] UKSC 24, in which the Supreme Court unanimously held no-oral-modification clauses effective. Lord Sumption, with Lady Hale, Lord Wilson and Lord Lloyd-Jones, put it that party autonomy operates up to the point when the contract is made, but thereafter only to the extent that the contract allows. (A paragraph number for that passage circulates widely from secondary sources. It is not reproduced here because it has not been checked against the judgment.) The Court rejected the inference that an informal agreement to vary carries an implicit agreement to waive the formality. The natural inference from non-compliance is not that the parties intended to dispense with the requirement but that they overlooked it. Lord Briggs concurred on narrower grounds: a no-oral-modification clause binds unless the oral agreement expressly, or by necessary implication, also varies that clause.

Estoppel survives, narrowly. It requires words or conduct unequivocally representing that the variation was valid notwithstanding its informality, and something more than the informal promise itself, and its scope cannot be so broad as to destroy the certainty for which the parties stipulated. Barclays Bank plc v VEB.RF [2024] EWHC 3088 (Comm) extends the point to no-waiver clauses, holding that a clause providing no waiver is effective unless in writing and executed by each party is not confined to consensual waivers, unilateral waiver by words or conduct is excluded too.

The practical escape route is not formality but construction. Vainker accepted that an e-mail or the issue of a drawing may be sufficient writing. On a modern project the real question is therefore whether a drawing revision, an RFI response or a meeting minute, objectively construed, amounts to an instruction. That is a construction question, and it is where the argument should be pitched. A contractor arguing that the formality should be excused loses. A contractor arguing that a revised drawing issued for construction was objectively an instruction to build something different has a case.

Australia never adopted Rock Advertising, and that changes the answer

In Australia a no-oral-modification clause cannot prevent the parties from orally agreeing to vary the contract. Party autonomy is treated as continuing after formation, and the clause is relevant context in deciding whether the parties in fact intended to vary, not a binding constraint. The foundational authority is Liebe v Molloy (1906) 4 CLR 347 at 353–355, and it is a construction case about extras: work done outside the written contract with the owner's knowledge and acceptance, notwithstanding a requirement for written orders, gives rise to an implied promise to pay.

Rock Advertising has not been adopted. Bundanoon Sandstone Pty Ltd v Cenric Group Pty Ltd. TWT Property Group Pty Limited v Cenric Group Pty Limited [2019] NSWCA 87 at [122] (Bell P, obiter, that no-oral-modification clauses provide "important context") and White v Philips Electronics Australia Ltd [2019] NSWCA 115 at [42] both show appellate interest in reconsidering the doctrine, and both courts found it unnecessary to decide. Displacing Liebe v Molloy would require the High Court. The recorded negative finding is worth stating plainly: no Australian appellate decision post-2019 revisits whether Rock Advertising should be adopted. The equitable limb runs through Update Constructions Pty Ltd v Rozelle Child Care Centre Ltd (1990) 20 NSWLR 251.

That does not make an oral direction costless under AS 4000:2025. Clause 36.1 makes writing constitutive: a variation is effective only where directed in writing by the Superintendent and before the Date of Practical Completion, and the 2025 edition now allows Practical Completion to occur before the certificate issues, so the window may close earlier than the paperwork suggests (the sub-clause numbering for Practical Completion in the 2025 edition is reported inconsistently across published summaries and is not given here). The synthesis has three steps. An oral instruction is not an effective clause 36 direction, so the Superintendent's pricing machinery in clause 36 is never engaged and the contractual route is closed. It does not prevent the Principal and Contractor making a binding subsequent oral or implied agreement. It does not displace estoppel. But both surviving routes require proof of consensus with the Principal, not merely a direction from a Superintendent or site representative: a materially harder evidentiary case, and precisely the risk shift the 2025 redraft achieves.

The statutory overlay that may cut across all of it

Two Australian statutes may now reach formality clauses, and whether they do is undecided. Section 13A of the Building and Construction Industry Security of Payment Act 2002 (Vic), commenced 15 April 2026 and retrospective to all construction contracts, and section 16 of the Building and Construction Industry (Security of Payment) Act 2021 (WA), for contracts entered on or after 1 August 2022, allow an adjudicator, court, arbitrator or expert determiner to declare a notice-based time bar unfair where compliance is not reasonably possible or would be unreasonably onerous. The provision then has no effect in that particular case only.

For variation claim notices the position is clear: a clause barring a claim not notified within 7 or 14 days of a direction is a paradigm notice-based time bar, and these provisions reach it, which is why the Victorian and Western Australian analysis now belongs alongside the ordinary notice and time bar analysis. For variation formality clauses (provisions limiting recovery to work performed after scope approval, rather than barring an unnotified claim) the position is genuinely unresolved. The Victorian definition of "notice" is expansive and may capture them, Clayton Utz flags the point, no determination exists, and there is no Western Australian case law applying section 16 to give interpretive guidance either. That is the whole of what can be said. If clause 36.1's written-direction requirement were held capable of being declared unfair, the central protection of the 2025 redraft would be substantially undercut in Victoria.

Canada: Colautti waiver by conduct, and its 2026 counterweight

Canada sits between England and Australia. Colautti Construction Ltd v Ottawa (City), 1984 CanLII 1969 (ON CA). (1984) 46 OR (2d) 236 is the leading authority that a written-change-order requirement can be waived or varied by conduct. Cory J.A. held that the parties, by their conduct, had varied the terms of the contract requiring extra costs to be authorised in writing, so that the City could not rely on its strict provisions to escape liability. The appeal was allowed and a new trial ordered.

Two limits have to be stated with the case or it is being cited too widely. First, the finding rested on several oral changes made and paid for: a demonstrated course of dealing, not informal comfort. One unpaid oral instruction will not do it. Second, the onus stays on the contractor: in D & M Steel Ltd v 51 Construction Ltd, 2018 ONSC 2171 the builder failed on the extras because there was no evidence of approvals for the specific change orders beyond its own uncorroborated evidence. Acquiescence plus a bare oral assertion is not enough.

The modern limit is Dependable Mechanical Systems Inc v Concord Adex Developments Corp, 2026 ONSC 21, in which the court gave effect to a contractual requirement of written notice within seven working days and held that informal email statements may not constitute a binding waiver of escalation claims. Cite it alongside Colautti: informal comfort is not waiver.

Note also what the CCDC prohibition does and does not do. CCDC 2 – 2020 GC 6.1.2 provides that the Contractor shall not perform a change in the Work without a Change Order or a Change Directive. That is a prohibition on the Contractor, not by its terms a bar on recovery for work actually directed and performed, which is why Colautti does so much work in Canada. And there is a recorded negative finding that shapes the pleading: no Canadian appellate decision on the ostensible authority of a CCDC Consultant to bind an Owner to an extra was located. Given GC 2.1.1's express limitation, plead Colautti waiver by the Owner's own conduct rather than ostensible authority of the Consultant. A counterparty who has read the contract cannot easily assert reliance on apparent authority contradicted by an express clause.

Do anti-waiver clauses waive themselves?

Sometimes. This is a United States question, and the distinction that decides these cases is pattern versus incident. A course of conduct waives. A single indulgence does not, and the threshold is the same wherever waiver is available at all. Transpower Constructors v Grand River Dam Authority, 905 F.2d 1413 (10th Cir. 1990) held that anti-waiver clauses are themselves subject to waiver through a consistent practice of non-enforcement. Rissler & McMurry Co v Sheridan Area Water Supply Joint Powers Bd, 929 P.2d 1228 (Wyo. 1996) found no waiver where written field orders were regularly issued throughout construction and later rolled into change orders.

The two cases are not in conflict. In Transpower the formality had been abandoned in practice. In Rissler & McMurry it had been observed, and one departure from an observed practice proves nothing. O'Malley Investment & Realty Co v Trimble, 5 Ariz. App. 10, 422 P.2d 740 (1967) puts the Arizona private-work position more strongly still: parties are "wholly unable" to limit future contractual action by a present provision, so an anti-waiver clause cannot bind prospectively.

Across every regime that permits waiver at all, the practical threshold is the same and it is high: repeated, documented, employer-level acceptance of the very informality now disavowed (signing, certifying and paying informal variations over a sustained period) plus contractor reliance. The onus sits on the contractor everywhere. This is the evidence that builds that case, and it has to be assembled contemporaneously, because it cannot be reconstructed at the end of a job.

Who may instruct is a separate question from whether it was written

A written instruction from the wrong person is worth no more than an oral one from the right person, and the two failures are routinely confused. Every standard form names the person whose instruction adjusts the price, and on every project someone with less authority than that gives directions which the contractor follows. The doctrinally sound route out is not ostensible authority (which runs into the express limitation) but the principal's own conduct. The table below states form-default positions: bespoke amendment to the instruction and authority provisions is normal on major projects, and the executed contract governs.

Form-default. Who may instruct is read off the published forms. The trap column is the corpus's reading. Bespoke amendment is normal, and the executed contract governs.

The certifier's inability to waive is now settled at the highest level available. In Uniform Building Contractors Ltd v Water and Sewerage Authority of Trinidad and Tobago [2026] UKPC 2, on FIDIC, Sir Peter Coulson held that the Engineer's role is administrative and certifying, not constitutive of the parties' contractual rights, and that the Engineer cannot waive procedural requirements or dispense with notice, because that would amend the contract beyond its delegated authority. Only the parties can waive. The reasoning is general and applies with equal force to a Contract Administrator, a Project Manager and a Consultant.

Which is exactly why the pleading order matters. Vim Engineering Pte Ltd v Deluge Fire Protection (SEA) Pte Ltd [2023] SGHC(A) 2 makes the point cleanly: at first instance the project manager lacked authority to waive the written-instruction requirement, and yet the Appellate Division found that the employer had waived it by its own representatives' conduct across 32 signed claims. The formality can be waived by the party whose protection it is, even where its agent could not have waived it.

The confirmation route almost nobody uses, and what to do this week

Most standard forms contain a route that converts an oral instruction into a written one, and it is rarely used on site and frequently decisive in the ensuing dispute. Under JCT DB 2024 clause 3.7 and JCT SBC 2024 clause 3.12, an instruction given otherwise than in writing has no immediate effect, but the Contractor may confirm it in writing within 7 days, and if the Employer or Architect does not dissent in writing within a further 7 days, the instruction takes effect at the expiry of the second period.

The rest of the machinery is worth knowing in the same breath. The Employer or Architect may instead confirm at any time before the Final Payment or Final Certificate, and under JCT SBC 2024 the Architect may sanction in writing a Variation made without instruction. JCT retained the procedure unchanged in the 2024 suite. Under FIDIC 2017 Sub-Clause 3.5, where the Engineer issues an instruction not identified as a Variation which the Contractor considers to be one, the Contractor must give Notice immediately and before commencing the work, and the Engineer must respond within 7 days by confirming, reversing or varying it. Under FAR 52.243-4(b) the notice must state the date, circumstances and source of the order and that the Contractor regards it as a change order. Both elements are mandatory.

So, concretely, the same week:

1. Send the confirmation letter within seven days, to the named person. Under JCT that is the Employer under DB 2024 or the Architect/Contract Administrator under SBC 2024, under FIDIC the Engineer, under AS 4000:2025 the Superintendent, under FAR the Contracting Officer. A confirmation addressed to the wrong person is worthless. Under AS 4000:2025 this letter now does double duty, because the Superintendent's failure to dissent is the evidentiary bridge to agreement or estoppel with the Principal.
2. Describe the direction, not the entitlement. Date, who gave it, what was said, what work it requires. The claim can be priced later. The record cannot be created later.
3. Diarise the second seven days and check whether a dissent arrived. If it did, the argument moves immediately to whether the direction was a variation at all.
4. Keep the alternative pleading alive from day one. Instructed variation first, then constructive or deemed variation, then waiver or estoppel, then quantum meruit. Waiver pleaded on its own is the weakest position available in every regime surveyed, and in three of them it is not available at all.
5. Read the supplementary conditions before relying on any of this. Employer amendments routinely tighten the confirmation clause or delete the deemed-effect limb, and Part 6 of CCDC 2 – 2020 is almost universally amended.

About this material Library content is general information about construction claim practice, not legal advice. Entitlement, deadlines and procedure are governed by your own contract and by the law of the place the work is performed. Reviewed August 7, 2026 · Report a correction