Quantum in Construction Disputes: The Complete GCC Guide

1. What Quantum Means in a Construction Dispute

"Quantum" is the money side of a dispute: how much is owed, by whom, and why. In construction it covers the value of work done, the value of changes to that work, the cost consequences of delay and disruption, the cost of putting defects right, and the sums due when a contract ends early.

Every construction dispute has two questions running in parallel:

• Entitlement (liability) — is a party entitled to be paid, or compensated, under the contract and the governing law?
• Quantum — if so, how much?

Lawyers and tribunals tend to focus on entitlement, because that is where the legal argument lives. But a claim that succeeds on entitlement and fails on quantum is a hollow victory. Tribunals regularly find in favour of a claimant on principle and then award a fraction of the sum claimed, because the figures were inflated, unsupported, double counted or disconnected from the events relied on.

On large GCC projects — airports, metro and rail systems, energy and utilities, high-rise and mixed-use developments — the quantum issues are often the most document-heavy and time-consuming part of the case. A well-run quantum case narrows them early. A badly run one buries the tribunal in schedules nobody can follow.

2. Who Gives Quantum Evidence — and Who Doesn't

Several professionals work on the money in a construction dispute. Their roles overlap, but they are not interchangeable.

The key distinction is independence. A quantity surveyor or claims consultant works in their client's interest. A quantum expert witness owes an overriding duty to the tribunal or court, must be transparent about method and assumptions, and must concede points where the evidence requires it. That independence is what makes the evidence persuasive.

It also explains why a party should generally not rely on the person who authored its claim as its independent expert. The tribunal will want to know that the expert has tested the claim, not defended it.

3. The Contract as the Valuation Framework

Before an expert values anything, they need to understand what the contract says about value. The contract sets:

• The pricing basis — lump sum, remeasurement, cost-reimbursable, target cost, or a mix.
• The pricing documents — bill of quantities, schedule of rates, activity schedule, payment milestones.
• The valuation rules — how variations are valued, when contract rates apply, when new rates are set, and what happens when nothing in the contract fits.
• The payment mechanism — interim valuations, payment certificates, retention, advance payment recovery and the final account process.
• Limits and exclusions — caps on liability, exclusion of consequential loss or loss of profit, liquidated damages, and notice requirements.

Most major GCC projects use FIDIC forms (most commonly the Red and Yellow Books, in their 1999 and 2017 editions) or bespoke contracts heavily based on them, often with extensive particular conditions. Government and semi-government employers frequently amend the standard valuation and payment provisions. The amended contract — not the standard form — is the expert's starting point.

Why this matters: a common failure in quantum evidence is to value on a "fair and reasonable" basis when the contract prescribes a specific method. The other side's first question in cross-examination will be: "Where in the contract does it say that?"

Whether a contractual provision is enforceable, and how it is interpreted under the governing law, are questions for the lawyers and the tribunal. The quantum expert's job is to value on the basis instructed — and, where the legal position is disputed, to value on each alternative basis.

4. Valuing Variations

Variations are the most common source of quantum disputes in the region. Projects in the GCC are frequently redesigned during construction, accelerated to meet launch dates, or changed to reflect new authority requirements — and the valuation of those changes is where large sums sit.

The valuation hierarchy

Most construction contracts, including FIDIC forms, follow a broadly similar hierarchy for valuing a variation:

1. Use the contract rates where the varied work is of similar character and executed under similar conditions to work priced in the contract.
2. Derive rates from the contract rates where the work is similar but not identical — adjusting for differences in quantity, specification or conditions.
3. Set new rates (often called "star rates" or "fair rates") where there is nothing suitable in the contract, based on reasonable cost plus an allowance for overheads and profit.
4. Daywork where the contract provides for it and the work cannot properly be measured.

The arguments are usually about which step applies. Was the varied work really of "similar character"? Were the conditions really "similar"? A contractor will often argue that changes in sequence, access, quantity or timing take the work outside the contract rates; an employer will often argue that the rates still apply.

Omissions

When work is omitted, the contract normally deducts its value at contract rates. Disputes arise where an omission is used to give the work to someone else (which many contracts do not permit), where the omission affects the pricing of remaining work, or where the contractor claims loss of the overhead and profit recovery it expected from the omitted work.

Constructive and disputed variations

Many variation disputes are not about value at all, but about whether there was a variation. Constructive variations — changes that were never formally instructed, but were required by the engineer's comments, a design development, or an authority requirement — are common on design and build projects. Whether a change is a variation is a question of entitlement. The quantum expert's job is to value it if it is, and to make clear which items are only valuable on that assumption.

5. Final Accounts

The final account is where every unresolved issue on a project comes home. Remeasurement, variations, provisional sums, dayworks, claims, contra-charges, liquidated damages, retention and advance payment recovery all have to be reconciled into a single figure.

Why final account disputes are hard

Final account disputes are rarely about one large issue. They are about hundreds of smaller ones, each with its own records and arguments. Without a disciplined reconciliation, the parties talk past each other — one side's total is built on a different structure from the other's, and the tribunal is left with two irreconcilable numbers.

The reconciliation schedule

The core tool is a reconciliation schedule: a single list of every item in the account, with each party's value side by side, the difference, the reason for the difference, and the expert's assessment. It becomes the working document for the rest of the dispute — for expert meetings, the joint statement and the hearing.

A good reconciliation:

• uses one item structure that both parties can map to;
• separates questions of principle (is this item payable at all?) from questions of figures (if it is, what is it worth?);
• carries totals that reconcile to each party's pleaded figure, so nothing falls through the gaps;
• identifies which items depend on other experts — for example, prolongation costs that depend on the delay expert's periods.

Items that cause the most argument

• Remeasurement — quantities on remeasurable contracts, and disputes about which measurement rules apply.
• Provisional sums — how they were expended, and whether attendances, overheads and profit apply.
• Dayworks — whether daywork sheets were signed, timely and properly priced.
• Contra-charges — back-charges for defects, damage, cleaning and services; often poorly documented.
• Payment history — reconciling interim certificates, payments actually made and the cumulative value of work.
• Advance payments and retention — release and recovery, especially after termination.

6. Termination Accounts

When a contract is terminated before completion, the quantum questions change. The account no longer adjusts a contract sum for a finished project; it has to establish what each party owes at the date of termination, and what losses flow from it.

What a termination account usually includes

Depending on who terminated, why, and what the contract and the governing law provide, a termination account may include:

• Value of work done at the termination date, assessed on the contract's valuation basis.
• Materials and goods — on site, off site, ordered and paid for.
• Demobilisation costs — removal of plant, temporary works and personnel, and cancellation of subcontracts and supply orders.
• Loss of profit on the remaining works — where the contractor claims wrongful termination and the law and contract allow recovery.
• The employer's cost to complete — where the employer claims the excess cost of completing the works with another contractor.
• Deductions — payments already made, advance payment balances, liquidated damages and other set-offs.

The cost-to-complete problem

An employer's cost-to-complete claim compares what it actually paid to finish the works with what it would have paid the original contractor. The quantum questions are whether:

• the replacement scope matches the original remaining scope (or includes extras and upgrades);
• the replacement price was reasonable for the market at the time;
• the employer's costs of re-procurement, supervision and delay are properly attributable;
• defective work by the original contractor is counted once, not twice (in rectification and again in cost to complete).

Market conditions matter. Re-procuring a half-finished project in a heated GCC construction market can cost far more than the original tender — and the parties will argue about how much of that premium is caused by the termination and how much by the market.

Loss of profit on remaining works

Where a contractor claims profit it would have earned on the uncompleted works, the starting point is usually the profit margin in its tender, tested against its actual performance on the project to date. A contractor that was losing money on the job will find it difficult to persuade a tribunal that it would have made a profit on the rest.

Whether lost profit is recoverable at all, and on what basis, depends on the contract and the governing law — matters for the lawyers.

7. Defects and Rectification Costs

Defects claims are where quantum and engineering meet. The quantum expert cannot value a remedy that no technical expert has endorsed — and a technical expert's remedial scheme is only half the claim until someone prices it.

Scope first, then cost

The valuation of a defects claim follows a strict order:

1. What is defective? — established by the technical expert (structural, building pathology, materials, products, building services).
2. What remedy is reasonably required? — again a technical question: is the proposed repair necessary, or does it go further than the defect requires?
3. What does that remedy reasonably cost? — the quantum question.

If the quantum expert prices a scope the technical expert has not endorsed, or the technical expert endorses a scope the quantum expert has not priced, the claim is exposed.

Betterment

Betterment arises where the remedy leaves the claimant with something better than the contract required — an upgraded specification, a longer design life, or a wider repair than the defect justifies. A tribunal will usually not award the cost of an upgrade. The quantum expert's role is to price the reasonable remedy, identify the cost of any element that goes further, and show the figure with and without it.

Cost of reinstatement vs diminution in value

In some cases the cost of putting a defect right is out of proportion to the benefit. The alternative measure is the diminution in value — the difference between the value of the asset as built and its value as it should have been built. Which measure applies is a legal question for the tribunal. The expert's job is to provide the evidence for each, so the tribunal can choose.

Associated costs

Defects claims often include costs beyond the repair itself:

• investigation, opening up and testing;
• temporary works and protection;
• decanting occupants, lost rental income or business interruption;
• professional fees for designing and supervising the repair.

Each needs its own evidence. Lost revenue claims, in particular, usually need forensic accounting support.

Structural defects: where the two disciplines meet

Structural defects — cracking, excessive deflection, reinforcement corrosion, post-tensioning failures, settlement — are among the highest-value defects claims in the region. The remedy can range from local repair to strengthening to partial demolition, and the cost difference between those options is enormous. The structural expert decides which remedy is technically required; the quantum expert prices that remedy and the alternatives.

8. Time-related Costs: Where This Guide Meets Delay

Prolongation, disruption and acceleration costs are a major part of construction quantum. They are covered in depth in our Delay & Disruption Quantum Guide, so this section is a summary.

• Prolongation costs compensate for the extended duration of the project — time-related site overheads, extended preliminaries, supervision, plant and equipment standing, site accommodation, and in the GCC frequently labour camp, transport and visa-related costs. They depend on the periods of compensable delay established by the delay expert.
• Disruption costs compensate for lost productivity — work taking more resources than it should have — and must not overlap with prolongation costs.
• Acceleration costs cover the additional resources, shift working and premium procurement used to recover or prevent delay.

Two principles run through all three:

1. Costs follow periods. Time-related costs should be valued for the periods in which the compensable delay actually occurred, using the costs actually being incurred in those periods — not an average across the whole project.
2. Each cost is claimed once. Prolongation, disruption, acceleration and head office overhead claims must be reconciled so that no cost is recovered twice.

9. Head Office Overheads, Loss of Profit and Financing Costs

Head office overheads

A contractor's head office costs — management, finance, procurement, IT, premises — are recovered through its projects. When a project is delayed, the contractor may argue that its head office resources were tied up for longer than planned, so it lost the opportunity to recover those overheads (and earn profit) on other work.

There are two broad ways to prove such a claim:

• Actual cost approach — identifying specific head office costs that increased because of the delay. This is the most persuasive approach but the records rarely support it fully.
• Formula approaches — using a formula (commonly referred to as the Hudson, Emden or Eichleay formulas) to estimate the overhead that would have been recovered over the period of delay.

The arithmetic is simple. The evidence is not. Tribunals generally treat formula-based claims with caution unless the contractor shows that:

• it actually lost the opportunity to earn the overhead elsewhere (for example, by evidence that it turned down work or could not bid because its resources were committed);
• the percentage used reflects its actual overhead and profit, from its accounts, rather than a tender assumption;
• the delay period is compensable, as established by the delay evidence;
• the claim does not duplicate overheads already recovered in prolongation costs or in the value of variations.

Loss of profit

Loss of profit claims arise in several forms — profit on omitted work, profit on uncompleted work after termination, and lost profit on other opportunities. The quantum expert, often working with a forensic accountant, tests the claimed margin against the contractor's tender, its actual performance on the project and its historic profitability. Whether profit is recoverable in principle is a matter for the lawyers.

Financing costs and interest

Late payment and extended projects cost money to fund. Financing claims should be built on the claimant's actual funding arrangements — overdraft rates, facility costs, the cost of capital — rather than an assumed rate. Interest on sums awarded is governed by the contract, the governing law and the tribunal's directions; the expert calculates on the basis instructed and, where the basis is disputed, on each alternative.

10. Global and Total-cost Claims

A global claim links several events to a single, undivided sum of loss without showing how each event caused part of it. A total-cost claim goes further: it takes the contractor's total cost, deducts what it was paid (or its tender), and claims the difference as caused by the employer.

These claims are attractive to claimants because they avoid the hard work of linking each event to each cost. They are vulnerable for the same reason. A total-cost claim implicitly assumes that:

• the tender was accurate and achievable;
• the contractor itself caused none of the overrun;
• no other risk event (for which the employer is not responsible) contributed;
• every cost was reasonably incurred.

If any of those assumptions fails, the whole claim can fall with it.

Tribunals do not always reject global claims outright — sometimes the records genuinely do not allow events to be separated. But they look hard at whether the claimant could have done better, and they will deduct for any cause that is not the respondent's responsibility. The quantum expert's role, on either side, is to test the assumptions, identify the parts of the claim that can be itemised, and show what survives.

11. Records: What Proves Cost and What Doesn't

The single biggest factor in a quantum case is the quality of the records. Tribunals give most weight to documents created at the time, for the purpose of running the project — not documents assembled once the dispute began.

Records that carry weight

• Cost ledgers and job cost reports tied to the accounting system
• Invoices, purchase orders and delivery notes
• Payroll and timesheet records, ideally allocated by activity and area
• Plant and equipment records — hire invoices, utilisation and standing records
• Subcontract accounts and payment records
• Interim payment applications and certificates
• Daily and weekly site reports, progress photographs and programme updates
• Engineer's instructions, site memos and correspondence

Records that carry less weight

• Estimates prepared after the event
• "Allocations" of costs to events with no contemporaneous basis
• Tender allowances used as a substitute for actual cost (unless the contract provides for it)
• Summaries without the underlying documents

Practical points for the GCC

• Multi-entity contractors often book costs across group companies, labour supply entities and equipment-holding companies. The expert needs to trace costs to where they were actually incurred and check for internal mark-ups.
• Labour costs may include camp accommodation, transport, visas and end-of-service benefits. Whether those are time-related, and how they were allocated across projects, is often disputed.
• Currency and tax — costs incurred in different currencies, and the treatment of VAT, should be handled consistently and transparently.
• Records in Arabic and English — translation of key records should be planned early, not left to the weeks before a report is due.

12. Alternative Figures and "Agreed as Figures"

Two practices distinguish good quantum evidence from poor quantum evidence.

Alternative figures

Where the facts or the legal position are disputed, the expert shows the figure on each party's case — and, where relevant, on intermediate positions. The tribunal does not have to accept the expert's view of the facts; it can make its findings and then read off the corresponding number.

An expert who presents only one figure — their client's — forces the tribunal either to accept it or to construct its own figure without expert help. Neither helps the party that appointed them.

"Agreed as figures"

Experts agree an item "as figures" when they agree its value if entitlement is established, without agreeing that it is. For example, both experts may agree that if the night-working premium in Section 4 is payable, it is worth AED 57,600 — leaving the tribunal to decide only whether it is payable.

Agreeing as figures narrows the dispute dramatically. In a large final account, it can reduce hundreds of items to a short list of genuine questions of principle — saving hearing time and cost for everyone.

13. The Quantum Expert's Report, Joint Statement and Hearing

When to appoint

As early as possible — ideally before the statement of claim or defence is finalised. Early involvement lets the expert identify missing records while there is still time to find them, test the structure of the claim, and help the legal team avoid pleading figures that cannot be proved.

The expert report

A quantum expert report should:

Expert reports in the region are typically prepared to meet the expectations set by the IBA Rules on the Taking of Evidence in International Arbitration (2020), where adopted, the CIArb Protocol for the Use of Party-Appointed Expert Witnesses in International Arbitration, the rules of the relevant institution (such as the DIAC 2022 Arbitration Rules), and the expert evidence requirements of the DIFC Courts, ADGM Courts, QICDRC and BICC.

Joint meetings and the joint statement

Tribunals commonly direct the experts to meet, without the lawyers, and to produce a joint statement listing what is agreed and what is not — with reasons. For quantum experts, the joint statement is usually built around the reconciliation schedule, with each item marked as agreed, agreed as figures, or disputed.

The hearing

At the hearing, the quantum expert is cross-examined on method, assumptions and figures. Tribunals in the region increasingly use expert conferencing ("hot-tubbing"), where the opposing experts give evidence together and answer the tribunal's questions side by side. Clear, consistent, independent evidence performs best in that setting.

14. Common Quantum Mistakes in GCC Disputes

15. What to Do Now