Claims · Contract Changes

Variation Claims Under Construction Contracts

How to identify, notify, and claim for variations under FIDIC. Notice requirements, cost assessment, and the interplay with other claim routes.

6 min read · Updated 24/04/2026

In this article

1. Variation Claims: Definition and Distinction from Other Claims
2. Contractual Framework: Variations Under FIDIC
3. The Variation Process: Notice, Documentation, and Agreement
4. Characterizing Your Entitlement: Time and Cost Relief
5. Variations vs. Claims: When to Use Each Route
6. Expert Assessment and Dispute Resolution

Key takeaway

Variations are Employer-directed changes to the scope of work, governed by strict contractual procedures. Notice of variation is mandatory; failure to follow procedure can forfeit entitlement to payment or time relief. Understanding when to characterize an entitlement as a variation (rather than a claim under other clauses) is essential to successful recovery.

1. Variation Claims: Definition and Distinction from Other Claims

A variation is a change to the scope of work directed by the Employer (or Engineer acting on the Employer’s behalf) after the contract has been executed. It differs fundamentally from other claim routes because it is an authorized change, not a breach or unexpected event.

Variations may include:

• Addition of work (e.g. extra rooms, additional finishes, extended programme duration).
• Omission of work (e.g. deletion of a phase, reduction in scope, cost savings).
• Changes to specification or materials (e.g. upgraded finishes, alternative structural solutions).
• Changes to method or programme (e.g. acceleration, change in phasing, change in working hours).
• Changes to contract price (where the contract includes a price adjustment mechanism).

The critical distinction: A variation is ordered by the Employer. If the Contractor undertakes change work without an Engineer’s instruction, it may not be entitled to payment—it has voluntarily expanded its scope. Conversely, a claim (under other contract clauses) arises from an unexpected event, breach, or risk allocated to the Employer—not from an Employer order.

2. Contractual Framework: Variations Under FIDIC

FIDIC contracts empower the Employer to order variations and establish a formal procedure for costing and timing relief.

FIDIC 1999 Red Book: Clause 13

Clause 13 grants the Engineer the authority to order variations. Key provisions:

• Clause 13.1: The Engineer may order any variations to the works, including omission or addition of work.
• Clause 13.2: The Contractor must not vary work without an Engineer’s instruction. The Contractor has no right to claim payment for unauthorized variations (unless separately justified under other clauses).
• Clause 13.3: The Engineer assesses the variation cost and time impact and issues a Variation Order (VO) or an interim instruction with cost/time to follow.
• Clause 13.5: Rates in the Bill of Quantities apply to variations where applicable. If no rate exists, the variation is valued at fair rates and prices.

FIDIC 2017 MDB Harmonised Edition: Clause 13

Clause 13 in the 2017 edition is largely similar but with added protections for the Contractor. Key changes:

• The Contractor may propose variations (not just accept imposed ones).
• The Engineer must assess variations within 28 days of receipt of the Contractor’s request.
• If the Engineer delays issuing a Variation Order, the Contractor may proceed and seek cost/time relief.
• Price and time for variations must be assessed before or as part of the VO, reducing disputes.

3. The Variation Process: Notice, Documentation, and Agreement

Successful variation claims depend on strict adherence to contractual procedure. Failure to follow procedure can result in loss of entitlement, even if the work was properly performed.

Step 1: Identification and Notice

When the Contractor identifies a need for variation (either because the Employer has ordered a change or because the Contractor proposes an alternative), it must issue written notice to the Engineer promptly. Under FIDIC 1999, the Contractor must provide:

• Clear description of the proposed variation.
• Reason for the variation (Employer direction or proposed optimization).
• Estimated cost and time impact (including labour, materials, preliminaries, and any disruption).
• Request for Engineer’s instruction to proceed.

Failure to provide timely notice may constitute a waiver of the right to claim cost or time relief. Some contracts are strict: no notice within the prescribed period = no claim.

Step 2: Documentation and Substantiation

The Contractor must provide supporting documentation to justify the variation cost and time:

• Quotations from suppliers for additional materials.
• Daywork records or labour rates for additional workforce.
• Equipment hire quotes if additional plant is required.
• Schedule analysis showing the impact on critical path and programme dates.
• Site photographs or inspection notes demonstrating work performed.

Contemporaneous documentation strengthens the claim. Reconstructed records months after the event are viewed with suspicion by Engineers and arbitrators.

Step 3: Engineer’s Instruction and Agreement

Once notice and documentation are submitted, the Engineer issues an instruction to proceed. The Engineer may:

• Agree the cost and time: Issue a formal VO with agreed cost and EOT. The Contractor may then proceed with confidence.
• Propose revised cost/time: If the Engineer disputes the Contractor’s estimate, it may issue a VO with a lower cost. The Contractor may accept or dispute.
• Issue interim instruction: Direct the Contractor to proceed pending final cost/time assessment (under FIDIC 1999). The final VO follows within a specified period.
• Refuse the variation: If the variation is not justified or is outside the Engineer’s authority, the Engineer may decline. The Contractor may then appeal or seek relief under other contract clauses.

4. Characterizing Your Entitlement: Time and Cost Relief

Variation claims may result in two forms of relief: time (EOT) and cost. These are assessed separately.

Cost Relief: Calculation Methods

FIDIC Clause 13 establishes a hierarchy for valuing variations:

• Method 1: Apply rates from the Bill of Quantities, if available and applicable.
• Method 2: If no BoQ rate exists, use rates from similar items in the contract.
• Method 3: If no applicable rate, fair rates and prices are agreed or assessed by the Engineer.
• Method 4 (Dayworks): If the variation cannot be valued by any method, daywork rates (labour, plant, materials) are applied.

Time Relief: Extension of Time (EOT)

If the variation causes delay to the critical path, the Contractor is entitled to an EOT proportionate to the delay caused. The EOT:

• Must be assessed against the programme and critical path activities.
• Is granted as calendar days, not working days.
• Is independent of cost—the Contractor may be entitled to EOT even if the Engineer grants no cost relief (e.g. acceleration for the same price).
• Removes or reduces exposure to Liquidated Damages (LD) for the delayed period.

5. Variations vs. Claims: When to Use Each Route

Not all changes can be pursued as variations. Understanding when to use the variation clause versus other claim clauses is strategic and can determine success or failure.

Variations: Employer-Directed Changes

Use the variation clause when:

• The Employer or Engineer has explicitly directed a change in writing.
• The change is to scope, specification, or method, not due to a breach or unexpected condition.
• The variation is covered by the Engineer’s authority under the contract.

Claims Under Other Clauses: Unexpected Events and Breaches

Use claim clauses when:

• Unforeseeable Physical Conditions (FIDIC Clause 4.12): Ground conditions differ from those indicated in the contract documents. The Contractor encounters rock, contamination, or water not foreseen. Recovery is for additional costs incurred in managing the unexpected condition.
• Employer Breach: The Employer or Engineer fails to perform a contractual obligation (e.g. fails to issue drawings on time, fails to grant access to the site, provides inaccurate site information). Recovery is for cost and time caused by the breach.
• Suspension of Work (FIDIC Clause 8.8–8.11): The Employer or Engineer suspends the works. The Contractor is entitled to cost of demobilization, remobilization, and extended preliminaries during the suspension period.

6. Expert Assessment and Dispute Resolution

When a variation claim is disputed—either because the Engineer rejects it, undervalues it, or delays issuing a VO—the Contractor may escalate to arbitration or expert determination.

Common disputes over variations include:

• Scope: Whether the proposed change is within the scope of a variation or is a separate breach claim.
• Cost: Whether the Contractor’s cost estimate is reasonable or inflated. The Engineer may propose a lower cost, and the Contractor disputes it.
• EOT: Whether the variation caused delay to the critical path. The Engineer may grant no EOT; the Contractor claims it caused project delay.
• Notice: Whether the Contractor issued timely notice. If notice is late, the Engineer may refuse the claim; the Contractor argues the delay did not prejudice the Engineer.

In arbitration, expert evidence is critical. A quantity surveyor (QS) expert can assess the reasonableness of the cost claim with reference to market rates and the contract methodology. A schedule analyst expert can demonstrate the critical path impact. These experts often resolve variation disputes by providing objective, independent assessment of the Engineer’s position.

Early expert assessment—even before formal arbitration—can identify weaknesses in your claim, suggest areas of compromise, and often lead to negotiated settlement with the Engineer, avoiding costly and protracted arbitration.

Navigate Variation Claims with Expert Guidance

Variation claims are governed by strict contractual procedures. A missed notice deadline or incorrect cost characterization can forfeit your entitlement. Whether you are pursuing a variation, disputing the Engineer’s assessment, or defending against a claim, expert assessment of your position is essential. Our team can review your notice compliance, validate your cost and time calculations, and prepare persuasive submissions to the Engineer or arbitrator.

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